Geo Notes (224)
Geo Notes (224)
O`LEVEL 2248
TOPICS
A map
Uses of maps
- To locate places.
- To determine where you are going.
- To show distribution of features and type of materials.
Conventional sign
- Is a standard sign used on a map to indicate a particular feature. The conventional sign may be a letter of the alphabet or it may
be a symbol.
1. Brown: land or earth features - contours, eroded areas, prominent rock outcrops, sand areas and dunes, secondary or gravel roads
2. Blue: water features - aqueducts, canals, furrows and siphons, coastlines, dams, lakes, marshes, swamps and vleis, pans, rivers,
water-towers
3. Green: vegetation features - cultivated fields, golf courses, nature and game reserve boundaries, state forest boundaries, orchards
and vineyards, recreation grounds, woodland
4. Black: construction features - roads, tracks, railways, buildings, bridges, cemeteries, communication towers, dam walls,
excavations and mine dumps, telephone lines, power lines, wind pumps, wrecks, ruins, trigonometrical stations, boundaries
5. Grey: construction features - built-up areas, cadastral information.
6. Red: construction features - national, airdrome and main roads, lighthouses and marine lights; pink also shows international
boundaries
Five Elements
Scale
- A scale is the ratio of a distance between two points on a map and the actual distance of the same two points on the ground.
This is a graphical representation of the amount by which the represented reality has been reduced.
2) Ratio scale
- Ratio – 1: 50 000.
- One unit on the map is equal to 50 000 units of the same size on the ground or 2cm to represent 1km.
Direction
An approximate way of describing position of one place in relation to the direction makes use of 16 cardinal points, the four main
ones being North, South, East and West
Direction is a generalised method of showing the position of one place from another i.e. points of a compass.
Bearing
a) With a pencil, draw a line parallel to the side of the map through spot height 735. (This is your True North line Oº).
b) Join the two spot heights with a pencil line.
c) Measure (with a protractor) the angle between True North, Oº ( i.e. the line through spot height 735 and parallel to the side of the
map) and line joining two spot heights.
d) The answer is 106°
Magnetic bearing
Magnetic Bearing is the distance in degrees from Magnetic North (i.e. from where the compass points to North) to the position
of the place.
The magnetic bearing between A and B is angle y = 112º
Map Referencing / Co-ordinates
Height
Height on all maps and photos is shown in metres above sea level.
On the topographical map, the contour interval i.e. the vertical distance between 2 contour lines is 20 metres.
On the orthophoto map, the contour interval is 5 metres.
Height is used to show the following:
Relief.
Intervisibility.
Gradient.
Cross-sections.
Vertical Exaggerations.
Height is shown on maps in various ways – always in metres above sea level i.e. as altitude.
Contour lines.
Spot heights.
Trigonometrical beacons.
Bench marks
Gradient
This is the steepness of a slope, and is represented as a ratio e.g. 1 : 50, 1 : 500.
The smaller the number, the steeper the slope.
HE = Measure the distance between the 2 points in cms, and convert to metres.
Divide the top answer by itself, divide the bottom answer by the top. +The answer is a ratio i.e. no units must be given.
Example 1:
Calculate the average gradient from Trig Beacon 96 to Spot Height 447.
8. Intervisibility
This is the concept of whether one place on a map can be seen from another.
It is decided upon by studying the heights between the 2 places. Any ground which cannot be seen behind a higher height is
known as dead ground.
If a convex slope is between the two places, the second cannot be seen.
A rough cross-section sketch shows this more easily.
Finding Area
The formula for the area of a rectangle is length x width (i.e. the length of one long side multiplied by the length of one short
side).
give your answer in either square metres (m2) or square kilometres (km2
Remember to convert your map distances to real distances before you multiply.
W
Area of irregular shape
Follow the rule that parts of a square are to be counted if they are half or more than half occupied, but are to be ignored if less
than half.
Count the number of occupied squares and multiply the total by 1𝑘𝑚2 .
Cross-Sections
It is a diagram showing change in height along a line drawn between two or more points on a map.
Place your strip of paper along the bottom line and move it up keeping your starting point on the vertical axis. When the first
height on your piece of paper corresponds with the same height on the vertical axis, mark its position with a dot. Now repeat this
for each height on your strip of paper.
This is used as the vertical scale must be exaggerated because, if the horizontal scale were used for the vertical, the relief would
show as an almost flat line on a cross-section.
VE = 1: 2 000
1: 50 000
1 1
VE = 2000 ÷ 50000
VE = 25 times
Description of Relief
Slopes
Slope is the gradient of land surface. Concave Slopes
Gentle slope is one in which land doesn’t rise or fall steeply. - One curved inwards.
-Contours are wide apart. - Contours are close together at the top and widely spaced at
the bottom.
A Valley
Steep Slope is here land rises or falls sharply. - A low area between higher grounds.
- Contours are close to each other. - Indicated by U-shaped contours pointing towards a higher
ground.
Convex Slopes
- One curved outwards.
- Indicated by contours which are close together at the bottom A Spur
and widely spaced together at the top. - Land which is projected from high to low ground.
- Indicated by U-shaped contours bulging towards lower
ground.
Irregular Shaped Hills
-A hill with some sides with uneven gentle and others with
uneven steep slopes.
Interlocking Spurs
- Spurs which appear as if to fit together. Ridges
- A range of hills with steep slopes on all sides.
- A ridge can contain hills, cols, passes or water shed.
Truncated Spurs
- Spurs in glaciated highlands whose tips have been eroded and
straightened.
Conical hill
-Hills are uplands which rise above relatively lower ground.
- Conical hills are small rounded hills.
A Col
- A low area which occurs between two hills.
A Pass
- A narrow steep sided gap in a highland.
A Water Shed
- The boundary separating drainage systems
which drains into different directions
Escarpment and ridges often form water sheds.
A Plateau
- A high flat land bound by steep slopes.
Escarpment
- A relatively continuous line of steep slopes
facing the same direction
- Has two slopes: a long gentle slope (dip slope)
and short steep slope (scarp slope).
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SECTION A
Weather
The state of the atmosphere at a particular place and time as regards heat, cloudiness, dryness sunshine,
wind and rain.
Climate
The weather conditions prevailing in an area over a long period or long term weather pattern of a given
area. It is measured by assessing patterns of variations in rainfall, temperature, humidity, etc.
Weather Climate
Day to day temperature and rainfall Describes average conditions expected at a
activity specific place at a given time
Measured for short term e.g. day to day Measured over a long period e.g. 30 yrs.
basis
The study of weather is called The study of climate is called climatology
meteorology
Weather report
Is a systematic statement of the existing and predicted meteorological conditions over a particular area
e.g. Kutsaga.
Weather Focast
Is a prediction of weather phenomena, trend and events.
Is made through data collection on temperature, rainfall and humidity and use of complicated modelling
and simulations to predict future weather.
Importance of weather
People can be aware of weather hazards such as cyclones hence take precautions against.
People will know the type of clothes to wear e.g. rain coats.
Decision making on farming time and crop type.
For aviation on taking off and landing time.
Sporting calendars as some games can be affected by bad weather.
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Air Masses
Is a large body of air with uniform temperature, humidity and lapse rate.
The region where air mass form is referred to as the source region.
Air masses are classified according to temperature and moisture characteristics and source regions.
In Zimbabwe, the continental air mass is resident while the polar maritime and tropical maritime also
reach the country.
Pressure
Air has weight therefore exerts pressure called atmospheric pressure.
Altitude, temperature and earth`s rotation affects pressure.
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Altitude – air pressure is higher at sea level than mountain tops. Pressure increases as air descends.
Temperature – the pressure increases as its temperature falls. North and South Poles have high pressure.
Pressure belts
Low temperature at Poles cause air to contract and high pressure develops.
Along the equator high temperature creates low pressure belts called doldrum low pressure / ITCZ.
Air crossing Poles creates low pressure belts along 60°N and 60°S.
Near 30°N and 30°S air begins to sink building sub-tropical high pressure belts called horse latitude.
Some of the high pressure in latitude moves over the surface towards the equator and poles.
There are three pressure systems: Polar High, Temperate Low and Sub-tropical High pressure.
Wind systems
Northern hemisphere
1. North East Polar winds – blow from the polar high pressure towards the temperate low pressure in
latitude 60°N.
2. South West winds – blow from sub-tropical high pressure in latitude 30°Nto low pressure zones.
3. North East Trade winds – blow from sub-tropical high pressure towards the doldrums along the equator.
Southern hemisphere
1. South East Polar winds – blow from high pressure towards low temperate regions in latitude 60°S.
2. North East winds – blow from the sub-tropical high in latitude 30°S towards the temperate low pressure.
3. South East Trade winds – blow from the sub-tropical high towards the doldrums.
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High temperature over northern Africa hence
High temperatures occur over Central and low pressure.
Southern Africa hence low pressure occurs. High pressure over southern Africa hence low
Temperatures are low over South Atlantic and temperatures.
Indian oceans hence high pressure. Tropical maritime air mass blows towards
North Africa and becomes cooler than the rest South Atlantic ocean towards the continental,
of Africa. west Africa towards Sahara low pressure.
Winds blow from sub-tropical high to low to They now blow from south west and become
the south. south west monsoonal winds.
Some winds come from desert and are dry and They are warm and moist.
dusty - harmattan winds. Areas south of the Sahara are warm and dry.
North East and South East Trades winds affect
east coast of Africa and south east coast
respectively.
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Rainfall Types and Patterns
Precipitation occurs when warm moist air rises.
Water vapour cools and condenses to form clouds .
Condensation produces small droplets which join together and grow to fall of their own weight.
Types include relief, cyclonic and convectional rainfall.
Types of rainfall
Relief or orographic
Results when warm moist air rises over a barrier e.g. mountain.
SE trade winds are forced over a barrier and rises, cools and condense and rain occurs on the windward
side e.g. Chimanimani or Inyangani.
Leeward side or rain shadow area is dry with little or no rainfall e.g the Save valley and Marange area.
Convectional
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Ground surface is overheated and air gets hot to generate convectional currents.
Air is heated by conduction, absorbing more moisture, expands and rises.
The ascending air remains warmer and hence become unstable.
It cools and produces cumulonimbus clouds.
Due to heat released by latent heat at condensation and freezing, thunderstorms are generated.
Rainfall in West and Central Africa is convectional.
Lightning, fires, death, flooding, strong winds, Landslides, destruction of homes, crops, and property.
Measures
Frontal or cyclonic
Two or more winds with different temperatures meet for example in Southern Africa.
The two air masses don’t mix but form a front.
The cold air mass is heavier than warmer air mass therefore, the light rises over the denser one.
Warm air cools,
Condensation and clouds form.
Rain occurs along the front.
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Inter – Tropical Convergence Zone (ITCZ)
Is a zone that goes right round the earth and is roughly parallel to the equator.
ITCZ brings about seasonal changes of winter and summer. It moves north and south following the sun
with a lag of 4-6 weeks.
The sun is overhead the equator on 21 March, Tropic of Cancer 21 June, equator again on 21 September
and Tropic of Capricorn on 21 December.
North and south of the ITCZ there are high pressure belts that encircle the earth.
This forces air masses to converge within this zone as they move from north and south to meet within
this zone.
ITCZ brings cyclonic rainfall in Southern Africa including Zimbabwe and sometimes areas like
Muzarabani and Tokwe-Mukosi affected by floods.
However, some types of rainfall do occur e.g. relief.
SE Trade winds – Are cool moist prevailing winds which blow throughout the year. Associated with
light showers and drizzle and often give rise to guti after the rain season. In summer they blow strongly
giving clear weather and cloudy weather in winter.
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Zaire /Congo air – They only blow in summer. Are the re-curved SE trade winds which approach Angola
into Zimbabwe via DRC by the intense low pressure of the ITCZ. They bring a lot of rainfall to
Zimbabwe and Central Africa because they collect moisture form the Atlantic Ocean and Congo
rainforest.
North East Monsoon – are seasonal winds which blow during summer and bring rainfall in northern
parts of Zimbabwe.
Ocean currents – have an influence on weather and climate as well as human activities.
1. Warm Mozambican currents – the warm Mozambican currents flows parallel to the coast of
Mozambique.
2. The Agulhas – flows parallel to the coast of Mozambique. Is made up of Mozambican current and
Madagascar currents.
3. Benguela current – flows along the coast of Mozambique.
4. Angola current – flows along the coast of Angola.
Clouds
o Are the fractions of the sky obscured by clouds when observed from a particular location.
o Cloud cover is measured in oktas.
o Sky conditions are estimated in terms of how many eighths of the sky are covered in cloud, ranging
from 0 oktas for clear skies to 8 oktas for overcast.
Classification of clouds
- Are classified according to height, form and appearance hence we have high, middle and low level
clouds.
High Level clouds – cirro is latin for high/crest and used for clouds found between 6000m to 12000m.
Middle level clouds – Alto means middle. Thse clouds range between 2100m to 6000m for example
alto-cumulus, altostratus and strato-cumulus.
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Lower Level clouds - Nimbus meaning water bearing and are below 2100m for example
cumulonimbus, cumulus, nimbostratus and stratus clouds.
Home work
Qn: Define cumulus, stratus and cirrus (6)
Types of clouds
1. Cirrus clouds – are wispy white clouds with a feathery and patchy cover. Have a silky sheen appearance.
Are made up of ice crystals and hardly block sunlight. They give the sun a red of yellow colour during
sunset and sunrise.
2. Cumulonimbus – are anvil shaped at the top. They extend over great vertical distance. They are black
or white heaped and are associated with heavy rainfalls and thunderstorms.
3. Nimbostratus clouds – are dark grey. They are dense and shapeless and associated with rain.
4. Altocumulus – white or grey and patched. Are made up of laminae or plates. When the sun passes over
them, they form a corona.
5. Altostratus clouds – composed of water droplets forming sheets of grey clouds partly covering the sky.
6. Stratocumulus – large globular masses, bumpy-looking. They are grey in appearance forming a regular
pattern.
7. Stratus clouds – are fog – like clouds forming a uniform layer. Bring dull weather accompanied by
drizzle.
8. Cirrocumulus – composed of ice crystals and is like ripples in the sand on a sea shore. They form a thin
cloud.
9. Cirrostratus – looks like a thin white transparent sheet that gives the sun and moon haloes.
10. Cumulus clouds – are round topped and flat – based forming a whitish-grey globular mass. Consist of
individual cloud units.
Frontal Systems
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Anticyclone
Cyclones
Are systems of intense low pressure.
They form over warm oceans where sea temperature exceeds 26℃ and in the tropics latitude 5 and 20
north and south of the equator.
Have lowest pressure at the centre.
Strong winds are deflected to the left in the northern hemisphere and to the right in the southern
hemisphere.
They rush upwards with great force forming a vortex which is the area that surrounds the eye of the
cyclone.
Give rise to torrential rainfalls and strong winds.
They occur in summer in southern hemisphere.
Examples cyclone Eline and Japhet.
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Prior to its arrival, air is still, humidity and temperature high.
Gusty winds and thin clouds as the front of vortex arrives.
Violent winds of high speed as vortex arrives, dense clouds and heavy rainfalls.
Calm condition as the eye arrives and passes.
Effects
a. Heavy rainfall, landslides and mudflows.
b. Destruction of houses, dams and bridges.
c. Blockages of roads and power lines.
d. Death due to lightning
Mitigations
Early warnings.
Building strong houses.
Afforestation as wind breaks.
Evacuating people from affected areas.
Relief and rescue operations.
Provision of food and safe water to the affected.
Depression
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Shown by closed isobars with low pressure at the centre.
Air circulates in a clockwise direction in southern hemisphere and vice versa.
Winds blow towards the centre.
Are associated with unsettled weather hence are termed extra – tropical cyclones or lows.
Rain occurs when warm moist tropical air is uplifted by the cold drier air.
Formation of a depression
Formed in temperate latitudes when humid tropical air meets cold polar.
Westerly winds meet polar winds.
A depression is formed at the polar front.
Frontal systems
Front – is a boundary between two air masses and are named according to which air mass is replacing the
other.
Warm Front
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Warm air displaces a cold air.
Air behind the warm front is warm and moist and that ahead is cooler and less moist.
Warm fronts have more gentle slopes than cold fronts hence leads to gradual air rise.
Gradual rise of air initiates continuous precipitation along and ahead of the warm front.
Are shown by a solid red line with semi – circles pointing the direction of its movement.
Cold front
Occluded
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Weather symbols and synoptic charts
- A synoptic chart is any map that summaries atmospheric conditions or a chart that makes use of
shorthand showing weather conditions of a place at a given time.
Land and Sea breezes
A breeze is a cool and calm wind resulting due to heating and cooling between land and adjacent seas
during day and night.
Sea breeze
The air creates an area of high pressure over the sea and low pressure over the land since land is hotter
than sea surfaces.
The sea absorbs heat slowly during the day and remains cool.
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A cool sea breeze moves from the sea towards the land.
The breeze reduces temperatures along coastal areas and may produce fogs.
Land breeze
Acid Rain
The smoke from burning fuels and chemical industries rises into the air and mixes with water vapour.
When the rain falls down it becomes acidic.
The acid rain is a weak acid made up of sulphuric and nitric acids.
Over, a long time (years for example), the rain eats into limestone installations as well as natural
landscapes, stone walks, statues and metals.
It also destroys vegetation as it has done to entire forests in the Eastern countries like the Black Forest
in Germany.
Has negatively impacted on tree growth in Scandinavian countries.
Since acids accrue in water they pose a health risk to humans and animals.
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Carbon Dioxide and Global Warming
Global Warming
Due an increasingly industrialised world a lot of Carbon Dioxide is being emitted into the atmosphere
from industries, motor vehicles, machinery and other human activities.
The solar irradiation from the sun comes mainly in the form of short UV radiation (light).
These are converted into longer infra-red waves (heat) when it reaches the earth’s surface.
Some of the heat is radiated back into the atmosphere by the earth’s surface.
Due to increased carbon emissions the amount of carbon dioxide in the atmosphere has increased.
This layer of Carbon Dioxide has an insular effect; it acts as a blanket preventing the longer waved
infra-red waves from escaping back into space.
The result is a general increase in the world’s mean temperatures.
This is known as global warming.
The effects of global warming include a general increase in mean temperatures in some places, the
melting of Polar ice resulting in sea level changes: this leads to flooding in low lying coastal areas,
destruction of Polar ecosystems, persistent droughts in some areas, flooding and mudslides due to
excessive rain in other areas for example Indonesia, freak weather storms and increasingly
unpredictable weather, droughts and increased aridity in some areas.
The effects of global warming are being compounded by deforestation.
Deforestation
Is the cutting down of trees without replacing them i.e. without reforesting.
The high demand for timber, wood and land cultivation has led to the continuous clearance of forests.
This reduces the humidity in the atmosphere and subsequently rainfall with long term effects of climate
change and desertification.
Deforestation also reduces the amount of trees which convert carbon dioxide back into oxygen resulting
in a retrogression on the speed of global warming.
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Ozone Layer depletion
In the upper layers of the earth’s atmosphere (between the stratosphere and the troposphere) there is a
layer known as the Ozone Layer.
It is composed of special bonds of Oxygen (O3) and about 30 km from the earth’s surface.
It acts a shield by blocking out the sun’s dangerous UV radiation from reaching the earth.
It is being depleted by chemicals from factories and some antiquated forms of aerosol sprays.
These make emissions containing nitrous oxide compounds, bromine and chlorine compounds.
These chemicals are often referred to as organohalogen, chloroflurocarbons (CFCs) and
Bromoflurocarbons.
They are depleting/reducing the Ozone layer by chemically breaking it down.
This has resulted in Ozone holes in some places.
This results in higher cases of non-melanoma skin cancer, eye cataracts and blindness and weakening
of human immune systems (immuno-supression) to people living underneath these Ozone holes.
Other effects include: reduced plant growth harming agricultural activities as well as natural vegetation,
reduction in plankton populations (these is the major source of food for most fish and features
prominently in marine ecosystems), loss of marine biodiversity, higher incidents of cancer in domestic
animals, adverse effects on flowering and pollination of plants and damage to important synthetic
materials like plastics and rubber.
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Due to a number of reasons the climate and weather of urban areas is different from the adjacent rural
areas.
Temperature
Although due to the presence of tall buildings light does not reach some areas especially alleyways and
narrow streets,
Normal buildings absorb heat during the day.
Dark-coloured roofs, concrete blocks and bricks all have a high thermal capacity which means they are
capable of absorbing heat energy during the day and releasing it slowly at night.
Additional heat is yielded by car fumes, factories, power stations and the high population concert rations
of people.
All things being equal urban build up areas experience higher temperatures which is highest in the CBD
and decreases gradually as one goes towards the edges.
Daylight temperatures are on average higher than surrounding areas generally by about 0.6°C.
Night temperatures are higher than surrounding areas due to the smoke and dust clouds over the
city/town creating a blanket/insular effect.
The mean winter temperature is also significantly higher as well as the summer temperature which
might be as much as 5°C higher.
Sunlight
Even though their temperature is higher, cities and towns receive less sunshine and more cloud cover
than their adjacent rural areas.
Dust and other particles over the build-up area absorb and reflect much of the sunlight preventing it
from reaching the city/town below.
Wind
Wind velocity is reduced by the buildings which create friction as well as act as windbreaks.
Urban wind velocities are typically lower than that of surrounding rural areas.
Sometimes however high rise building create wind tunnels which have streams of very high velocity
winds which trouble pedestrians and can sometimes knock them over.
There is reduced wind chill factor.
Small scale turbulence and eddies can occur as a result in temperature differences with adjacent rural
areas.
Relative Humidity
Relative humidity is lower in urban areas where the warmer air can hold more moisture and there is
lack of vegetation reducing the amount of evapotranspiration.
Clouds
Urban areas appear to receive thicker and up to 10% more frequent clouds
Precipitation
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Towns and cities receive more rains and thunderstorms.
This is a result of thermal currents within urban areas.
Also greater chances of rain, snow and sleet in urban areas.
Weather Hazards
1. Drought
Is a period of deficient rainfall leading to crop failure. Name areas more prone to drought in the world.
Human causes
Rapid population growth resulting in increased pressure on natural resources including water.
Deforestation.
Soil erosion.
Overgrazing.
Mono-culture.
Falling water tables due to ground water being used for domestic and agricultural activities.
Build-up of salts also known as salinisation has destroyed a lot of land making it toxic to plants.
Effects
Crops wilt and die there may be a significant reduction in yields.
Animals die from dehydration and shortage of pastures.
Shortage of drinking water.
Dust storms.
Death of people due to dehydration and starvation.
Malnutrition and associated conditions like Kwashiorkor these are more pronounced in children.
Poverty due to loss of livelihood.
Famine
Crops can become toxic due to an increase in aflatoxins especially to animals.
Can lead to nitrate poisoning in animals which are fed drought affected crops such as maize.
Wild fires become more frequent.
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Mitigation
a) Insurance schemes by farmers.
b) Stockpiling food crops.
c) Cloud seeding.
d) Growing drought resistant crops.
e) Early planting.
f) Irrigation and Donor Aid.
2. Floods
What are floods?
Causes
a) High rainfalls
b) Deforestation.
c) Siltation in rivers.
d) Melting of ice.
e) Concrete pavements in urban areas.
Mitigation
a) Widening and deepening river channels.
b) Straightening of river channels
c) Afforestation.
d) Use of check dams.
e) Early warnings.
f) Discourage settlements on low lying areas.
g) Relief and rescue schemes.
Lightning
Is made up of huge static discharge that is a result of differences in charge between the ground and
clouds.
Thunder results when a lightning flash heats and expands the surrounding air during the discharge
causing booming sound waves.
Effects
a. People die from lighting strikes.
b. Causes electrical surges in power grids and may damage unprotected electrical gadgets.
c. Damage buildings.
Mitigation
a. Lightning conductors.
b. Wear rubber shoes when going out during thunderstorms.
c. Don’t walk on higher grounds.
d. Do not carry or touch metal objects.
e. Do not walk through water puddles.
f. Do not shelter under tall trees or isolated buildings.
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Frost / snow
Effects of snow
Flights are grounded when extreme.
Hinders activities like sports.
Buildings and equipments can be buried hence inaccessible.
Roads are blocked.
Vegetation and crops destroyed.
Mitigations
Use of green houses.
Use smudge pots to heat orchards and fields.
Using heating systems in homes.
Clearing snow from roads.
Use of tires with grip to avoid slippery.
Hail
Effects
Hail does extensive damage to crops like tobacco.
Solutions
Growing crops in sheltered places like in green houses however it`s expensive.
Use of agricultural shade cloth.
Insurance schemes.
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LANDFORM STUDIES
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Mohorovicic is a boundary between the crust and mantle.
The Mantle / Mesosphere
Mainly composed of Sima and rocks rich in iron.
The rock is also known as olivine rock.
The rocks are solid in the top layer of the mantle.
The lower layer rocks known as asthenosphere are in semi – molten state.
It reaches a depth of about 2900 km into the earth.
Temperature reaches as high as 5000℃ and can generate convection currents.
Is separated by the Gutenberg discontinuity.
Being a boundary between the earth`s core and mantle.
The Core
Is made of two layers.
Is the most dense and heaviest part of the earth.
Comprises of metal nickel (Ni) and Iron (Fe) hence abbreviated NiFe.
Temperatures are around 6 200℃.
Inner core is liquid, plastic or semi – plastic i.e semi – molten and outer core is solid due to pressure
operating on it.
Continental Drift
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The sub-division of these two continents has resulted in the formation of present day continents.
Evidences on Continental Drift
1) The way some of the continents fit like a jigsaw puzzle. It is especially visible at Coastal Eastern South
America which fits into Coastal West Africa
2) Paleomagnetic dating and fossil remains- according to paleomagnetic dating, when rocks solidified they
were magnetised in the direction of the Magnetic North at that time. Using the data of information, the
scientists can tell where they were first formed and if they moved from these places.
3) Geological similarities of flora and fauna show that India, Australia, South America and Africa were
once joined together
4) In the Congo Basin, they were glacial deposits joined in the Antarctic, they were fossilised remains of
animals, plants and coral lime stones in the Greenland all show climatic different from what they are
today
Flora – plants
Fauna – animals
Plate Tectonics
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Major Plates Minor Plates
1. Eurasian Plate i. Iranian Plate
2. African Plate ii. Arabian Plate
3. Antarctica Plate iii. Indian Plate
4. Indo-Australian Plate iv. Carribean Plate
5. Pacific Plate v. Turkish Plate
6. North America Plate vi. San Francisco Plate
8. Nazca vii. Phillipine Plate
9. South America Plate viii. Cocos Plate
ix. Juan de Fuca Plate
Convergent Zone
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Known as destructive of zone of subduction.
Two plate move towards each other.
An oceanic plate moves towards a continental plate but being heavier,
The oceanic plate sinks or is subdued by the continental plate and is destroyed into the mantle giving
rise to deep – sea trenches and island arcs with volcanoes.
The oceanic plate and sediments are being destroyed, the zone termed zone of destructive.
When plates move towards each other, their edges are destroyed as they collide and push one another.
Nazca plate near Peru South America sinks under the South American plate (the Andes) and Juan de
Fuca sinks under the North American plate ( Rockiers) forming the island arcs of the West Indies.
Collision Zone
This is when two continental crust collide and as neither can sink.
They are formed into fold mountains.
For example the Indian plate collided with the Eurasian plate form the Himalayas and African plate
collided with the Eurasian plate forming the Alps.
Conservative / Transform Zone
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Examples include the San Andreas Fault in California.
Landforms include rift valleys e.g Great African Rift Valley.
Lakes also found e.g Lake Tanganyika in Tanzania.
Earthquakes and their Causes
Is a shaking, vibration, trembling or movement in the earth`s surface.
They are due to one tectonic plate sliding over or past another plate along a fault line.
May be due to volcanic eruptions when magma moves below or on the earth`s surface like the
movement of plates.
Building dams and Lakes may result in minor earthquakes and tremors.
Zimbabwe, Zambia and Mozambique have experienced tremors due to weight of water building up in
Lake Kariba and Cabora Bass
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i. Focus – the point at which the earthquake originates and may be several kilometres below the
surface.
ii. Epicenter – the point where the earthquake hits the surface a point directly above the focus. It is
here the shock wave first hit which give rise to the earthquake. It is where the greatest impact falls
and damage is suffered. Where most damage occurs and the spreads away from this zone.
There are two types of earthquake shocks
i. Body waves
They travel through the earth`s crust in a vertical direction and are of two types.
Primary – they cause the crust rock to move back and forth in the direction of the waves
Secondary – these cause the crustal rock of the earth to move from side to side i.e. they operate at right
angles with primary waves and direction of movement.
ii. Surface waves
They travel through rock surfaces and are of two types.
Cause most damage to infrastructures and loss of life.
Love (L) waves – these cause the surface rocks to move from side to side at right angles to the direction
of the wave movement.
Rayleigh (R) waves – cause rock surfaces to have a vertical – circular movement.
Other Terms
1. Intensity – the degree or capacity of the earthquake to cause damage. It is measured using the Mercali
intensity scale.
2. Magnitude – is measured using a seismograph now known as seismometer. It records the vibration
caused by an earthquake. Known also as its scale being measured on a Ritcher scale ranges from 0 to
13. It is a logarithmic scale set to base 10 so a magnitude of 5 is ten times greater than that of 4 and
10 000 ( 1 followed by 5 zeros) greater than 1.
3. Aftershock – is an earthquake that occurs in the aftermath of a previous earthquake usually within days
or hours of the main – quake in the main area of the same main quake. If it is large than the
Factors affecting the impact of an earthquake
Distance of concerned area from epicenter for example coastal areas are at risks from tsunami when it
occurs at the sea.
The magnitude.
More developed countries are better equipped to predict and do rescue operation thereafter.
Climate of an area and time of the year may increase diseases epidemics and mudslides.
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Time of the day especially the rush hour is more devastating.
Relief such as Nepal impedes forms of rescue.
Folding
Is the transformation of the earth`s structure into folded landforms as a result of compressional forces.
Tectonic movement result due to earth`s internal forces.
When forces move horizontally towards each other they are compressional forces.
Rocks are subjected to this force in a process called folding.
Rocks either fold or fault due to their brittleness or flexibility.
In folding, some rock layers buckle and form folds.
Types of folding
Symmetrical folds – is when both limbs are equal in steepness on both sides because the compressional
sides are equal and opposite.
Asymmetrical fold – occurs when one side is steeper than the other due to forces on one side which are
more than the other force.
Over-fold – results when one fold is pushed over the adjoining limb due to increasing compressional
forces.
Recumbent fold – occurs when the limbs are nearly parallel to each other and the axis of the fold is
horizontal.
Over – thrust fold
Occurs when the recumbent fold is acted upon by extreme powerful compressional forces which cause one
of the limbs to fracture. The upper part of the recumbent fold is thrust forward along the fracture plane.
- Other landforms resulting from volcanic activities include hot springs and geysers.
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A spring is a point on the earth`s surface where water flows naturally from the ground.
A hot spring is a stream of hot water flowing out of the ground.
The water is heated when it comes into contact with molten hot rocks below the earth`s surface.
The water then flows out as a spring naturally as a fountain e.g. Nyanyadzi and Rupisi near Mutare in
the Eastern Highlands of Zimbabwe.
Geyser
Is a hot spring that throws jets of hot water and steam into the air due to heating in the pipe of the geyser.
The temperature of water rises resulting in pockets of steam trapped in the twisted portions of pipe.
Eventually steam builds enough pressure and forces the water in the upper part of the pipe to be spouted
and sprayed violently into the air.
E.g is found in Yellowstone National Park in the USA.
Landforms resulting from Folding
1. Anticlines, Nappe folds, Overthrust, Overfold, Recumbent, Fold mountains.
Anticline and Syncline
1. Anticline
Is a fold that is arched upwards to form a ridge of mountain.
It can be defined as a highland area or ridge formed due to compressional forces.
It is convex shaped and is formed out of rock units that are folded in the same pattern.
It results from a simple fold and each side of a fold is called a limb.
The topmost point is called a crest / axial line.
The crest acts as a line of symmetry between two limbs.
2. Syncline
Is a fold that arches downwards to form a fold.
Are made up of rocks units that are folded in the same pattern. Usually concave shaped.
Usually occur in conjunction with anticlines which is like the letter n.
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3. Over thrust
If compression forces continue to act on the rock layers, a simple fold is formed; progresses into an
asymmetrical fold, then an over fold and lastly into an over thrust which is actually a fault.
4. Over – fold
Occurs when one fold is pushed over the adjoining limb due to increasing compressional forces.
Also known as overturned fold.
5. Recumbent
Occurs when the limbs are nearly parallel to each other and the axis of the fold is horizontal.
6. Fold mountains
Problems
- Difficult to build in due to the steep sided valleys.
- Roads and other communications links have to snake their way up wherever they can, and often these
roads are not big enough to adequately service a large community.
- The climate is very cold and wet, meaning that most industrial and agricultural activity is difficult.
For farmers they have a very short growing season, and it is difficult to use machinery on the steep
slopes.
- Avalanches are a constant threat, as was seen to devastating effect in Ranrahirca, Peru, in 1962. Huge
amounts of money are spent each year to try and combat the avalanche threat, especially with the
large amount of tourists using the mountains.
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Faulting
Refers to the fracturing of breaking of the earth`s crust due to both compression and tension forces as a
result of tectonic movements.
Lateral earth movements often produce very great stresses due to compressional forces and tensional
forces.
These forces can cause fractures or breaks in the earth`s crust forming joints.
If the rocks are displaced on both side of the crack it is called a fault.
Faulting normally displaces the crustal blocks along lines and eventually rocks are pushed above or
dropped below the general level of land.
Features of a simple fault
Caused by tension forces which cause part of the earth to move downwards.
The central block is a fault plane to the right of the central block is displaced downwards.
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2. Reverse fault
It is due to tear forces which are in opposite direction and this normally results in rift valleys.
Effects of Faults
Producers of earthquake.
Petroleum and oil deposits found in porous sedimentary rocks.
Also give rise to underground ground water table along fault planes resulting in hot or cold springs.
May also give rise to waterfalls.
Difficult to build roads and railways.
Vulcanicity
Refers to various ways by which molten rock and gases are forced into the the earth and onto its surface.
Includes volcanic eruption forming volcanoes, lava plateaus and geysers.
Also involves intrusive and extrusive features e.g. batholith and sills.
When magma (molten rock) reaches the surface is known as lava.
Vulcanicity occurs most at plate boundaries.
Vulcanicity is divided into intrusive and extrusive vulcanicity.
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Qn: What is intrusive and extrusive vulcanicity? (4)
A Volcano
Is an opening in the earth`s surface through which magma is injected into the earth or ejected as lava
onto the earth`s surface.
Rocks below the earth`s crust have a very high temperature but the great pressure exerted on them by
the earth`s crust keeps them in a semi – solid state.
Friction at plate boundaries raises their temperature and fuelling great pressure due to faulting and
folding hence rocks become molten and semi- fluid.
It is this magma that flows up into cracks in the earth`s surface forming landforms like dykes, batholiths,
sills and lapolith.
Volcanoes erupt violently or quietly.
Types of Volcanoes
Are large craters that form at the top of a volcano usually two or more killometres in diameter.
They are deep and can extend downwards for some hundred meter with lakes as in active volcanoes e.g.
Lake Bosumtwi in Ghana.
Formation
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Violent eruption
A composite volcano may explode violently that its top is blown off and disintegrates into rock masses
and ashes. Thereby forming a crater at the top of the volcano.
Subsidence
It may form due to block subsidence or downward displacement of the central block.
After an eruption, the supply of magma is depleted causing a huge chasm to form beneath the volcano.
The weight of the cone sometimes develops faults which may cause the cone to collapse into the chasm
beneath e.g. Longonot in Kenya.
Meteor theory
This suggests that solid objects from space fall by gravity and on impact with the volcanic cone.
Mountain collapse
A mountain may collapse if it has a large mass floating on a wetter surface resulting in a caldera.
Extrusive volcanic landforms
Are those landforms resulting as a result of magma solidifying on reaching the earth`s surface e.g. cinder
cone, acid cones, composite cones and plug cones.
Magma sometimes reaches the earth`s surface through a vent, fissures and cracks (called lava).
If the lava emerges from through the vent form a cone shaped mound called volcano.
If it emerges out of a fissure it builds and forms a lava plain or plateau.
Volcanic cones
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The mount of a volcano is its cone.
It is made up of lava or lava and rocks torn by molten magma.
It may contain layers of ashes and small bits of lava known as cinders.
The shape and size of the cone depends on the nature of materials and type of eruption.
It has a pipe where the lava flows out and the exit of the pipe is the crater.
Cinder cone
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The shape and slope depends on whether the lava is fluid or viscous.
Basic / shield/ fluid lava is very fluid or mobile.
It spreads over some distance and forms gentle slopes e.g. Nyamuragira in DRC and Mauna Loa in
Hawaii with a diameter of 400km and a height of 9km from sea bed.
Basic lava cone
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It’s very high and it has alternate layers of cinder and lava and ash hence named stratovolcano i.e.
layered volcano e.g. Mount Kilimanjaro in Tanzania and Mt Cameroon in Cameroon.
1. Dyke
Is a sheet of magma that solidifies across bedding plane.
It can be vertical or inclined.
Dykes are easily eroded forming shallow trenches.
Those that resist erosion form ridges.
Dykes normally give rise to waterfalls for example Howick Falls in South Africa.
Other examples are the Jos Plateau in Nigeria and Kaap in South Africa.
2. Sills
A sheet of magma that lies along bedding planes.
A sill is a body of tabular rock that solidifies along bedding planes sometime are igneous intrusions.
Due to erosion they may form ridge like escarpments and others remain as caps on top of hills.
They can be dissected by rivers forming isolated hills.
The Three Sisters in Cape Province South Africa are buttes which have sills.
3. Batholith
A deep-seated dome like igneous intrusion made up of granite.
Is formed when a large mass of magma that accumulates in the earth`s crust which cools and solidifies
within or near the earth`s crust.
Sometimes they form the root or core of mountains.
They form features like dwalas and low lying hills after denudation processes.
They are essentially massive underground hills.
Example is Domboshava near Harare.
4. Lopoliths
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A saucer concave shaped sheet of magma that solidifies in the earth`s crust.
They form depression which holds water or form lakes.
Example is the Great Dyke in Zimbabwe is not a dyke according to geological fact.
5. Laccolith
Is convex shaped massive sheet of magma that solidifies within the earth`s crust and usually near the
earth`s surface.
They are arch – like igneous intrusions as a result of magma solidifies within sediments.
They have a pipe-like feeder coming from the magma pool very deep down.
Laccolith forces sedimentary rock to curve up and when exposed to erosion and denudation, they form
low lying hills.
For example Mt Mlanje in Malawi.
Bedding planes
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Earthquakes
Short term Effects
Loss of life.
Destruction of homes.
Landslides due to ground shaking.
Destruction of transport and communication networks e.g. roads.
Leads to nuclear disasters such as the Fukushima – Daichii in March 2011.
Power failure leads to blackouts.
Trade, commerce and industries are destroyed.
Tsunamis can result especially in coastal areas and may cause damage.
Long Term Effects
Spread of diseases such as cholera and dysentery due to unsanitary and shortage of clean water hence
loss of life.
Expensive rebuilding exercise e.g. in Nepal investments were directed towards repairs.
Fall of standards of living due to loss of income and livelihood.
Long term radiation effects including cancer, deformed births and cataracts.
Damage from aftershocks.
Mitigation
Disaster preparedness practice drills on dos and don`ts when an earthquake occurs.
First aid kits in homes.
Seismic studies to forecast the likelihood of an earthquake.
Disaster relief operations such as medicines, clean water and food supplies.
Provision of tents for shelter.
Rescue operations using earth moving equipments.
Donations towards reconstruction funds.
Building strong and more earthquake resistant buildings.
Communication methods e.g. radio to disseminate information.
Benefits and problems of Volcanoes
Benefits
Lava and ash form fertile soils for agricultural activities.
Geothermal electricity.
Contain precious minerals such as Opals and obsidian.
Tourist attraction.
Habitable islands for example the Hawaii islands in the Pacific Ocean.
Produce condensation nuclei.
Igneous rocks for building.
Caldera lakes as source of water.
Problems
Loss of life as in the Pombeii.
Destruction of crops due to lava flow as in Hawaii.
Loss of ecosystem and biodiversity.
Leads to acid rain and natural fires.
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Settlement disruption and displacement of people.
Can cause tsunamis. What are tsunamis?
Mitigation
Rescue operation to affected areas.
Dissemination of information through effective media when the eruption is predicted.
Diverting lava flows using barriers.
Monitoring volcanoes using latest seismic technology.
Evacuation from affected areas prior to the eruption.
Block Mountains and rift valley
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Recreation activities and tourism.
Disadvantages of rift valleys
Hot weather can be stiffing and enervating on valley floors.
Diseases such as malaria, bilharzia and typhoid abound in within.
Dangerous animals can be found in forests.
Flood occurrence.
Weathering
Is the disintegration of rocks into smaller particles which lie exposed to weather elements in situ.
In situ meaning in its original place or stationary.
Importance of weathering
Creates tourist attractions for example Epworth Kopje.
Produces soils valuable for agriculture and vegetation development.
Weathering helps in soil enrichment.
Without weathering, the concentration of the same valuable material may not be sufficient and
economically viable to exploit, process and refine.
Prepares the way for formation of not only regolith and soils, but also erosion and mass movements.
QN 1. State the differences between weathering and erosion. (8)
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Physical, chemical and biological / organic.
Physical weathering / mechanical
Is the disintegration of rocks into smaller particles by mechanical processes without any changes in the
chemical composition of the rock.
Likely to occur in areas of arid climates such as deserts, arctic regions and some with little or no
vegetation cover.
Typically produces sand soils.
Physical weathering processes include exfoliation, frost shattering, pressure release and thermal
shattering.
Exfoliation
Rocks expand when heated and contract when cooled similar to solid materials.
In arid areas diurnal temperature can exceed 50℃.
At night temperature falls and rock contacts and the outer layers cools faster than the inner parts.
Stresses develop within the rock causing the outer layer to peel off like the rings of an onion (Onion
weathering).
Also several different minerals within the rock expand and contract at different rates and result in
granular disintegration.
The exfoliation domes like Domboshava have been formed due to exfoliation.
It can be termed thermal expansion or insolation weathering.
Frost Shattering
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It occurs in rocks with crevices and joints and where there is limited vegetation cover and temperatures
fluctuate around 0℃.
During the day water enters through the crevices or joints.
When temperatures fall at night, water freezes leading to breakdown.
Ice occupies more space than water hence rocks expand.
As the water freezes within the rock it attracts more particles of water to form ice crystals which expands
further.
The rocks shatter and fall off the main rock as frost wedging.
Salt crystallisation
Saline water with some salts enters rock cracks or pore spaces.
Salt crystals form as evaporation takes places.
As crystals become bigger, they exert stress upon the rocks causing granular disintegration.
The process results in the development of weathering pits especially in deserts where water is drawn to
the surface of rocks by capillary action.
Pressure release / dilatation
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Intrusive landforms as batholith are formed deep below the surface and under intense pressure due to
the weight of the overlying overburden.
The removal of the overburden results in reduction in pressure which causes fractures to develop on the
top layers of the rock.
Cracks develop parallel to the surface in a process called sheeting forming exfoliation domes.
Chemical weathering
Refers to decomposition of rocks as a result of chemical processes and reactions altering the chemical
components of the rock.
Some rocks decompose when they get into contact with water, oxygen, carbon dioxide and some acids
(carbonic, humic, acid rain and smog).
Some minerals are susceptible to chemical weathering for example calcium.
Most active in humid regions.
Processes include oxidation, hydration, hydrolysis carbonation, organic wreathing and acid rain.
QN: Compare chemical and physical weathering. (8)
Oxidation
Occurs when rocks are exposed to oxygen in air or water.
Rocks containing iron react with oxygen as the rock transforms from ferrous state to ferric state
During rusting, rocks change colour and become reddish – brown.
This makes the rock easily crumble.
Reduction (opposite to oxidation) also occurs in waterlogged areas through a process known as gleying.
Hydration
Some rocks such as that have salt minerals have the capacity to absorb water hence swell and become
susceptible to future breakdown.
In hydration, rocks swell and exert pressure in addition to changing their chemical structure.
The rock swells during wet periods and contract during dry periods causing them to fracture and
breakdown.
Hydrolysis
Hydrogen ions in water react with mineral ions in the rock.
Water reacts with minerals in the rock instead of dissolving it forming compounds.
Is common in granite areas where feldspar in granite or igneous reacts with hydrogen to form clay.
Mica can also be affected by hydrogen ions in acidic water solutions.
Carbonation
Occurs when carbon dioxide dissolves with rain water to form carbonic acid.
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This weak acid reacts with rocks that are composed of calcium carbonate e.g. limestone.
The calcium is dissolved and removed as a calcium bicarbonate solution by running water.
This forms underground caves such as Chinhoyi caves and other limestone features such as stalagmites
and stalactites.
Solution
Some minerals like rock salt are soluble in water.
When they come in contact with water they dissolve in situ.
As the rocks dissolve in water they may form grikes/ grykes and clints which are known as limestone
pavements.
Biological / Organic Weathering
Decomposing vegetation forms humus which releases humic acid which attacks rocks in the process
called chelation.
Respiration of bacteria and plants root increases carbon dioxide levels in the soil hence increasing
carbonation.
Lichen extracts iron from rocks via reduction.
Burrowing and wedging by organisms like earthworms, rodents etc., help in exposing the new surfaces
to chemical attack and assists in the penetration of moisture and air.
Human beings by disturbing vegetation, ploughing and cultivating soils, also help in mixing and
creating new contacts between air, water and minerals in the earth materials.
Acid rain
Sulphur dioxide and nitric oxides react with water to form acid rain.
Acid attacks and corrodes limestone and other rocks such as sandstones.
Also, the acidic solutions tend to free up oxygen ions hence fueling hydrolysis.
Landforms resulting from Weathering
1. Dwalas
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- Are known as ruware in Shona, dwala in Ndebele and whaleback in English.
- It is a hill or rock which is dome shaped and rises several metres from the ground about 2.5m in height.
- Have gentle slopes, are rounded or elongated hills and are found in low lying areas.
- Have convex / rectilinear and gentle slope.
- Might have vertical joints as a result of pressure release.
- They are surrounded by deeply weathered regolith.
- They are usually bare of vegetation but can be lightly populated by shrubs and bushes.
Formation of dwalas
- An underground intrusion for example a batholith is exposed by denudation.
- The overburden is removed by denudation processes resulting in pressure release and the formation of
a dwala.
- Denudation refers to process or forces that wear away the land surface for example weathering, erosion,
transportation and mass wasting.
2. Karst landforms
a) Limestone pavements
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b) Stalactites
- Finger like masses of calcite hanging vertically from the roof of a limestone cave or cavern formed by
repeated evaporation of water and giving off of carbon dioxide from drops of water containing calcium
bicarbonate hanging from the roof of the cave causing crystallisation of calcium bicarbonate into calcite.
c) Stalagmites
- Stumpy rock masses of calcite which grow from the floor of a limestone cave upwards formed by repeated
dripping of solution of calcium bicarbonate from the end of stalactite to the floor of a limestone cave then
it spreads out and crystallizes.
d) Limestone Pillars
- Pillar like structures in limestone caves formed when stalactites and stalagmites grow towards each other,
stalagmite grows until it touches the roof of a cave or when a stalactite grows until it touches the floor of
the cave.
e) Limestone caves
- Underground chambers or cavities in limestone rocks.
- Underground rivers dissolve limestone in horizontal joints forming a horizontal tunnel.
- Surface water and underground water percolates through the joints into the tunnel enlarging it forming
a phreatic cave i.e. cave below the water table.
- The water flows out at the vauclusian spring lowering the water table causing the phreatic cave to
become a limestone cave.
- Continued solution from water percolating through the caves roof widens and lowers its floor to form
a larger cave called limestone cavern e.g. Carls band cave in New Mexico U.S.A.
Positive
- Features in karst scenery are a tourist attraction e.g. caves, gorges, stalactites, stalagmites, etc.
- Limestone rock is used in the manufacture of cement.
- Limestone blocks are also used for building.
- Limestone regions are very good for grazing particularly sheep because the surface is dry.
- Large villages called spring line settlements form at the line of vauclusian springs due to the availability
of water.
Negative
- Limestone landscape discourages settlement because the surface is rocky, soils are thin and unsuitable
for agriculture, surface is rugged with features like grikes and Clints and the water supply is inadequate
due to rivers disappearing into swallow holes.
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3. Inselbergs
- Are Island Mountain and termed manadnock in West Indian meaning an isolated mountain.
- Is an isolated rock hill, knob, ridge or small mountain that rises abruptly from a gently sloping plain.
- Are made of rock piles or blocks of rocks that rise from an area of flat lower terrain.
- Are dome-shaped and formed from granite gneiss and are also called bornhardt.
- Common inselbergs include castle kopjes, tors, conical hills and balancing rocks.
Tors, kopjes or castle kopje
- Tor is a Scottish word meaning a hill.
- Kopje is an Afrikaans word meaning a small isolated hill made up of granite rock piles.
- They are rock features made from weathering.
- They are usually less than 5m in height.
Formation
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- Result from subsurface weathering of domed landforms.
- Granite intrusions are weathered beneath the surface by chemical weathering processes.
- When rock is exposed the rotten parts are washed away by erosion.
- Weathering continues in form of physical and chemical due to rectangular joints on the rocks.
- If the joints are close together, the mass collapse and are washed away but if far away blocks of rocks
fall away from the main rock forming tors/kopjes.
Balancing rocks
Rain falling down on land flows down the slope as sheet flow, rill flow and gully flow all of which
contribute to stream discharge.
Underground water oozes at certain points called springs and also contributes stream discharge.
It is a type of overland flow or downslope movement of water which takes the form of a thin, continuous
film over relatively smooth soil or rock surfaces is generated when rain falling onto the earth’s surface
flows over the whole surface as a thin layer of water.
It commonly occurs at the head of the watershed where the slope is gentle and the surface flat e.g.
artificial surfaces, rocks etc.
Rill flow
Rills are shallow channels (no more than a few tens of centimetres deep) cut into soil by the erosive
action of flowing water.
As the slope steepens, the amount of water increases and sheet flow encounters surface irregularities
sheet flow turns into small shallow channels or rivulets known as rills.
Rills in turn join up with other rills and form gullies.
A gully is a landform created by running water, eroding sharply into soil, typically on a hillside.
Gullies resemble large ditches or small valleys, but are metres to tens of metres in depth and width.
The process by which gullies are formed is called gullying.
A gully may grow in length by means of headward erosion at a knickpoint.
Gullies are sometimes known as dongas.
Gullies empty into streams which are perennial rivers.
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The results of water erosion
Sheet flow results in sheet erosion.
This results in the washing away of fertile top soils and shallow soils.
Rock surfaces and plant roots are also exposed by sheet wash.
Rill flow results in rill erosion.
Gully flow results in gullies also known as dongas.
Both Rill and gully erosions results in the formation of dongas and ravines.
River profiles
The long profile-this is the cross section along the river’s entire length from its source to its mouth.
The short profile-this is the cross section across a river’s valley from the crest line( on one bank) to the
channel to the other crest line. This is known as the river’s valley.
There is only one cross profile but an innumerable short profiles that can be taken at any point in a
river’s length.
The short profile however tends to widen the further one moves downstream.
The diagram above shows the three main sections of a river/stream’s long profile and the diagram below
show the corresponding typical short profiles at each stage.
Short profiles that correspond to the long profile.
A river’s long profile can be divided into three sections viz: the upper course or headwater reaches, the
middle course or middle reaches, the lower course or the lower reaches.
The base level of a river is the lowest point a river can erode its channel, this is equal to the sea level of
the ocean into which the river empties.
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Upper course
Common features include: V-shaped narrow valleys, potholes, interlocking spurs, waterfalls and rapids,
gorges, strewn boulders.
The most dominant form of erosion is vertical erosion and headward erosion also takes place.
Middle course
It’s less steep, has more water volume, a wider channel and more velocity due to reduced channel
roughness.
Common features include: Open V-shaped valleys, truncated spurs, meanders, ox-bow lakes and braids.
Erosion is mostly in the form of lateral erosion.
Lower course
Is flat and has a very wide channel with less energy.
Common features include: bluffs and other flood plain features such as swamps, braiding, deltas,
alluvial fans, deferred junctions and natural levees.
These features are mostly due to deposition which is more dominant than erosion due to the reduced
river energy due to the lower gradient and increased wetted perimeter.
River processes
Rivers are perhaps the most important denudation agent.
They carve channels, form valleys, transport and deposit regolith over great distances and other material
to form other types of landforms.
River erosion
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River erosion involves the wearing away of rock and soil found along the river bed and banks.
It also involves the breaking down of the rock particles being carried downstream by the river.
There are four main processes of erosion (corrasion, attrition, hydraulic action and solution (also known
as corrosion).
Corrasion
Is the wearing down of the sides and bed of the river by the load as it is being transported by the river.
Corrasion occurs when a river picks up material and rubs its bed and bank wear them away by abrasion
like sandpaper.
Corrasion therefore happens when the river’s sides and bed are scrapped off by the material being
transported by the river.
This process is most pronounced during flooding.
This is the major means of erosion by which a river extends both vertically and horizontally.
If there are hollows in the river bed, pebbles can get trapped in these and whirled by turbulent eddies
(in circular motion) to form potholes.
When pebbles are trapped in existing potholes these are deepened further by the whirling pebbles.
Corrasion wears away the channel’s river bed and add more material to the river’s load thus amplifying
the processes as more load means more corrasion.
Attrition
Is a process by which the river’s own load is broken down from larger particles into smaller ones.
This happens because the river’s load which is made up of different sized particles which collide and
knock into each other causing them to break into smaller fragments.
As the load progresses downstream it gets smaller and smaller.
Also angular rocks become increasingly rounded.
Hydraulic Action
Refers to the sheer force and turbulence of the moving water which can be able to remove loose material
such as gravel, sand and silt.
This force can also weaken solid rocks by surging into cracks in the rock.
This processes can be aided when there is air in the cracks which is compressed causing eventual bank
collapse.
Cavitation is a form of hydraulic action caused by bubbles of air collapsing and the resultant shock
waves hit and weaken the banks of the river.
Hydraulic action by itself is very effective if the river does not have some load to produce corrosive
erosion/abrasive erosion.
Hydraulic action is the weakest and least effective form of erosion.
Solution or Corrosion
The water in the river dissolves some soluble rocks such as rock salt and sometimes limestone.
This is most effective in areas where the stream bed and banks are composed of soluble rock for example
in limestone regions
River transportation
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Any energy left after a river has overcome friction is used to transport sediment.
This energy varies directly with a river’s discharge, velocity and turbulence
That is if they increase the amount of a river’s energy to erode and transport also increases until a river
reaches flooding level when deposition is likely to occur due to an increase in the wetted perimeter and
thus friction.
There are three main processes by which a river’s load is transported: suspension, solution and bedload
(sometimes divided into saltation and traction making them four methods instead of three in this case).
Suspension
This is when light silt and mud floats along with the water.
Very fine particles of silt and clay are dislodged and carried away in the turbulence of the flowing water.
The greater the turbulence the greater larger the quantity and size of particles picked up by and carried
away by the river.
This partly explains why flooded river often have mud coloured water, it is due to the heavy amounts
of suspended material with the water.
The suspended material usually forms the largest part of a river’s total load.
It increases in amount towards a river’s mouth also giving the black/brownish colour to the water that
is similar to that of most rivers after a storm.
Solution/Dissolved Load
Is when material dissolves in the water and is carried away in solution form for example rock salt.
Flowing water within river channels almost always contain acids in the form carbonic and nitrous acids
especially after a storm or due to pollution.
This dissolves the bedrock especially if it is soluble for example limestone.
It dissolves in water and is carried away in solution form.
This is a very active form of transportation in limestone regions and in other regions it forms a
comparatively small part of the load.
Bed load
Is divided into two processes traction and saltation.
Saltation is when smaller particles bounce along the bed of the river.
Traction is when larger boulders and pebbles roll and are dragged along the river’s bed.
Since larger particles cannot be picked up by the current they are moved along the bed of the river in
these two ways.
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Saltation happens when pebbles, sand and gravel are temporarily lifted up by the river’s current and
bounced along the bed of the river in a hopping motion.
Traction occurs when the largest cobbles and boulders roll or slide along the bed of the river.
The largest loads can only be moved in this way during flood periods for example after a storm.
River deposition
Deposition occurs when a river no longer as sufficient energy to transport its load.
When its velocity begins to fall and has less energy, a river’s competence (maximum size of material
which a river is capable of transporting) and capacity (maximum amount of load that a river is capable
of transporting) falls and therefore deposition begins.
Deposition occurs when:
a) Discharge is reduced after a period of low precipitation.
b) Velocity is reduced upon the river reaching the dam, lake, sea or ocean resulting in the formation of
deltas.
c) Shallow water occurs on the inside section of a meander for example.
d) The load is suddenly increased for example in the event of a landslide for instance when a portion of
bank collapses into the river.
e) When the river overflows its banks so that the velocity outside the channel is reduced resulting in the
formation of a floodplain.
f) During floods, especially in the lower course rivers spread to the sides of the channel.
g) Frictional drag and the reduced gradient slow down the flowing water resulting in deposition.
Deposition
When the river loses its energy to any of the reasons pointed out above the following happens.
The heaviest material/load is deposited first this is why rivers are littered with boulders in the upper
course.
This is because traction load and siltation loads require more energy to transport.
The finest material is deposited last and may reach the sea where it is deposited onto and to form deltas.
The dissolved load which is in solution water is deposited at all but transported to the sea where it
maintains the saltiness of oceans.
The deposition of sand and silt leads to the development of a gently sloping plain known as a flood
plain.
Deposition can result in aggradation where the river’s bed and gradient are increased. This can happen
at deltas and on alluvial fans.
The following factors affect the river’s energy and ability to erode, transport and deposit its load.
Type of flow, gradient of channel, volume/discharge, cross-sectional channel shape, channel roughness
When water flows downhill under gravity it follows the path of least resistance.
There are two patterns of flow: laminar and turbulent.
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Laminar and turbulent
Laminar
Is a horizontal movement of water in a river with minimal vertical mixing.
The water is in layer; such a form of flow would result in minimal erosion and more deposition.
In reality such a type of flow does not exist although something close to this can be observed in flat
terrain when rivers are relatively calm during their flow.
Turbulent flow
Consists of a series of vertical and horizontal eddies and a lot of vertical mixing of the water as it flows
downhill.
Turbulent flow results in more erosion and transportation and this form of flow increases with an
increase in a river’s energy.
The gradient of the channel determines a river’s ability to erode, transport and deposit its load.
The upper course of a river is associated with steep gradients therefore a lot of velocity and energy and
therefore river erosion and transportation takes place in the upper course.
The middle and lower course have a much gentler gradient and therefore the slower moving waters have
less erosive power and therefore more deposition takes place and less transportation and erosion.
Discharge/Volume
As already said, water flows in response to the pull of gravity which is also determined by the mass and
in turn the volume of the moving water.
Rivers have less water in the upper course because of most have fewer tributaries at this stage therefore
they have less energy to erode.
Middle course and lower course river sections have higher volumes of water since they have more
upstream tributaries at this stage resulting in more energy to transport and erode and transport in terms
of water volume.
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Channel cross-section: A has less energy due to friction
Channel A has a larger wetted perimeter which means more friction and leaves less energy to erode its
bed and to transport load.
Channel B has a smaller a smaller wetted perimeter resulting in more vertical erosion because it has
more energy left over from overcoming friction.
In terms of channel cross section upper course streams have more energy to erode when compared to
lower and middle course streams.
Channel roughness
Channel roughness channel A) is typical in the upper course streams and B) in the lower course streams.
Upper course streams encounter more friction due to their rough channels which are a result of
protruding boulders and rocky outlines. This means such channels will have less energy left over to
erode and transport their load.
Middle and Lower course streams have more energy to transport and erode since they have smooth
channels resulting in less friction.
Conclusion
More erosion takes place in the middle course since the channels are smooth, the gradient steeper than
in the lower course, the wetted perimeter smaller than in the lower course and the volume of water is
high.
A lot of vertical erosion takes place in the upper course.
Most deposition takes place in the lower course of the river since the gradient is smaller, the wetted
perimeter larger, and the gradient considerably less steep when compared to the other two courses.
Landforms
- These can be broadly divided into those landforms resulting from erosion and deposition.
- Those from erosion include Narrow valleys, Interlocking spurs, Waterfalls and rapids, Pot holes,
Gorges.
- Those resulting from mainly deposition include Flood Plains, Meanders, Ox-bow lakes, Braids, Levées,
Deltas
A lot of river features such as floodplains and meanders are formed by both erosion and deposition
acting in tandem.
Interlocking spurs.
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Interlocking spurs occur mainly in the upper course section of streams and rivers as rivers have little
energy to erode.
Steep sided valleys
Since water flows in small amounts and in predominantly steep areas in the upper course section vertical
erosion is more dominant than lateral erosion.
This also facilitated by the load which the river carries because it cannot reach the upper levels of the
valley walls once they have been formed so much of corrasion processes are limited to the lower
sections of the river and this tends to deepen the channel.
The results are V-shaped steep sided valleys.
Meanders
Meander cross section
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Helicoidal flow in a meander.
This is a corkscrew like movement of the water as it spirals downstream from bank to bank as shown
in the diagram above.
This often occurs during floods and results in the formation of meanders and their associated features
such as pools and riffles.
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The lateral erosion results in undercutting of the river bank and the formation of a steep sided river cliff
these cliffs are also known as bluffs. The inner bend water is slow flowing, due to it being a low energy
zone, deposition occurs resulting in a shallower channel.
This increased friction further reduces the velocity (thus further reducing energy), encouraging further
deposition.
Over time a small river beach or runoff slope builds up on the inner bend.
The greater erosion of the concave bank occurs just downstream of the axis of the meander bend,
because the course of the maximum velocity zone in the channel does not reflect the meander shape.
This causes meander to migrate down the valley.
The lateral erosion of the meanders and their migration widen the flood plain.
A point bar
Is a depositional feature made of alluvium that accumulates on the inside bends of streams and rivers below
the slip-off slope.
They are crescent-shaped and located on the inside of a stream bend of meanders.
They show the former positions of a meander during its downstream migration.
The term is sometimes used synonymously with slip-0ff slopes although the term slip-off slope is used
to refer to the cross section and the term point bar is used to refer to the aerial view.
It is important to note again that meanders to not remain stationary but migrate downstream resulting
in the widening of the flood plain.
Gorge
Is a narrow valley between hills or mountains, typically with steep rocky walls and a river/stream
running through it.
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a) A gorge may develop if a river’s course follows a line of weakness such as a fault line. For example the
Kaduna river in Nigeria forming the Shiroro Gorge.
b) An actively flowing river may carve a gorge if it flows through a plateau which is made up of layers of
resistant rock alternating with lays of less resistant rock.
c) If the region in which the plateau is found is arid or semi-arid there will be little weathering of the valley
sides resulting in a narrow and deep gorge.
d) When the gorge is large it is sometimes referred to as a canyon for example the Fish River Canyon in
Namibia and the Grand Canyon in the United States.
e) The later was formed in part by the process of river rejuvenation.
f) Gorges can be formed due to vertical erosion in areas of vertical uplift.
g) They can also result from the collapse of underground caves in limestone regions.
h) Vertical erosion into resistant rock can also result into the formation of a gorge as the valley walls on
both sides of the river remain intact due to minimal weathering. For example the Lupata gorge was
developed when the river incised into resistant rhyolite rock.
i) A gorge can also result from the upward migration of a waterfall for example the gorges at Victoria
Falls.
j) Vertical erosion on a once buried hard rock layer by an existing stream in cases of superimposed
drainage.
k) Down-cutting of the predator or victor stream in cases of river capture for example the Pungwe Gorge.
The diagram above shows a gorge being formed as a result of a waterfall migrating upstream
Note this is just one of many ways in which a waterfall can be formed.
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Waterfalls commonly occur in the upper course section of the river although they can occur at any part
in a river’s course.
There are various ways in which a waterfall/rapid can be formed.
a) A sharp break in the bed of a river produces a waterfall.
b) A band of resistant rock with a vertical face overlying less resistant rock produces a waterfall when it
is exposed at the surface by river erosion can also result in the development of a waterfall.
c) A rapid is formed if the rock lies at a steep angle but is not vertical.
d) A waterfall can also develop when resistant rock overlies a less resistant is horizontal or dips gently up
river.
Rapid
e) A rapid might be formed first in such instances but continued erosion at the base of the pool will
resulting into the rapid developing into a waterfall.
f) A rapid develops when the resistant rock, overlying a less resistant rock dips gently down river.
The Victoria Falls are the widest falls in the world.
- They may have developed as a result of the river Zambezi uplift of an almost horizontal basaltic plateau.
- Where a river flows across a line of weakness it erodes vertically to form a waterfall.
The Victoria Falls may also have been formed in this way.
- It has retreated upstream along fault lines and might cease to exist one day.
- A river might descend the scarp in areas of faulting resulting in a waterfall at the knickpoint.
- A waterfall may also be formed where a river descends from a highland area (for example a plateau)
into a lowland area.
- A river might erode backwards to undercut and divert the water of a neighbouring stream and the point
of capture is marked by a waterfall.
- An example is the Pungwe Falls which marks the point where the Pungwe River captured the waters of
the Nyakupinga River which is a tributary of the river Odzi in the Eastern Highlands.
Plunge pool
Is deep pool that is formed at the base of waterfalls due the swirling water eroding the base of the
waterfall via hydraulic action and corrasion aided by bits of the hard rock that falls into the pool and
becomes part of the load and the eddying and turbulent motion of the water at the base.
As the undercutting continues the waterfalls migrate upstream.
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Floodplain
These are typically found in the middle and lower course sections of the river.
They are gently sloping surfaces of alluvium that result from lateral erosion and material deposited onto
the valley floor.
A flood plain commonly has the following river features alluvium, marshes, meanders and ox-bow lakes
which are remnants of cut off meanders.
When a river is in flood it overflows its banks and covers the whole plain upon which it deposits some
of its load.
The continual deposition results in the formation of levees.
Flooding causes deposition to take place on a river’s banks because the water is slower there and
therefore has less energy to transport the load.
As already said above, continued flooding results in the formation of raised banks.
These ridges are known as natural levees.
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Most flooding takes place at the edges of the channel since the water is slower
The river then flows above the level of the floodplain which causes tributaries to defer joining with the
main stream.
Tributaries flow parallel to the river, with some flowing into depressions resulting into swamps, while
others eventually join the main river further downstream forming what are known as deferred junctions.
Rivers that flow above the flood plain present great risk of flooding to nearby settlements for example
the (Yellow River) Huang Ho in China and the Mississippi in the United States.
Swamps/Marshes
This is stagnant water that is clogged with water loving vegetation.
They occur in the flood plain due to frequent flooding and where tributaries fail to enter the main stream
(i.e. deferred junctions where a tributary flows over a depression).
Oxbow lakes
An oxbow lake is a U-shaped body of water that forms when a wide meander from the main stem of a
river is cut off, creating a free-standing body of water.
This landform is so named for its distinctive curved shape, resembling the bow pin of an oxbow.
Development of Ox-bow lakes.
Ox-bow lakes form when an acute meander leaves a narrow neck separating the two ends of a meander.
Active lateral erosion takes place on the outside bends and break through this neck especially during
floods.
In flood the cut ends are sealed off by deposition and the meaner becomes an ox-bow lake.
The banks are steadily raised by depositions resulting tin the river lying above the level of the lake.
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The lakes gradually lose water as vegetation and sediment fill them up.
Deltas
Types of Deltas
1. Marine: Type formed at sea.
2. Lacustrine: at a lake.
3. Inland Delta: Deltas which form along a rivers course before it reaches the lake or sea.
Formation
The velocity of the river is checked on entering a relatively flat swampy land.
The river builds up levees.
The river bursts banks forming distributaries.
Alluvial deposits are spread over vast areas when river floods e.g. Niger and Okavango deltas.
4. Arcuate Delta
A delta with a convex shoreline on the seaward end due to strong currents spreading materials over a
wide area on seaward side.
Has many distributaries e.g. Tana and Rufiji deltas.
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5. Bird`s foot
6. Estuarine Delta
The rivers load is deposited on the estuary when the speed is checked by sea.
The river cuts across in a single channel that may be bordered by levees e.g. on R.Volta in Ghana and
on R. Zambezi.
Home work
Qn 1 (a) what are braided channels? [2 ]
(b) describe the formation of braided channels. [4 ]
River capture
This is a process where one River captures the headwaters on a nearby stream.
This can occur due to several reasons viz:
Tectonic earth movements, where the slope of the land changes, and the stream is tipped out of its
former course.
Natural damming, such as by a landslide or ice sheet.
Erosion, either: headward erosion of one stream valley upwards into another, lateral erosion of a
meander through the higher ground dividing the adjacent streams.
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In an area of karst topography, where streams may sink, or flow underground (a sinking or losing
stream) and then reappear in a nearby stream valley.
The process.
The diagram above shows how river capture can occur.
There are two consequent rivers: Stream A and B and Stream B has a tributary (subsequent A)
Stream B has higher discharge and thus higher erosional activity than stream A.
Stream B might also have a lower base level and thus increasing its ability to erode.
Subsequent A migrates upstream (headward erosion) until it reaches Stream A’s channel.
Through a process known as watershed migration Subsequent A enlarges its own drainage basin at the
expense of Stream A.
In time because Subsequent A and Stream B have a lower base level the headwaters of Stream A will
be captured and diverted into Subsequent A.
The point at which the headwaters of the minor river change direction is known as the elbow of capture.
Below this point a wind gap marks the former course of the now beheaded stream or misfit stream.
A misfit stream is a river whose headwaters were captured resulting in the stream flowing in a valley
that is too large to be accounted for by the low discharge.
A knick point and waterfall might form at the elbow of capture especially if the base level of the
capturing river is far lower than that of the beheaded stream.
Rejuvenation
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occurs when there is a negative change in a river’s base level (i.e. when the river’s base level falls)
which increases its potential energy and thus enables it to revive its erosive energy in the processes.
A river’s base level is the lowest point to which a river can erode.
A negative change in a river’s base level may be brought about by vertical uplift (for example isostatic
uplift) or by a fall in the level of the sea for example due to tides.
This change renews a river’s ability to erode due to an increased gradient.
A rejuvenated river erodes vertically into the floodplain to produce new features that are different from
those typically found in the flood plain.
Rejuvenation produces several features including: incised meanders, terraces and waterfalls/knick
points.
River terraces and incised meanders
River terraces are remnants of former floodplains.
Which following vertical erosion brought about by rejuvenation have been left high and dry above the
current and present-day flood plain.
If a river quickly erodes and cuts quickly into the floodplain a pair of terraces of equal height may be
seen flanking the flood plain creating a valley into a valley feature known as paired terraces.
Sometimes the river does quickly cut into the flood plain, allowing it to meander, resulting in one terrace
being removed as the meander migrates downstream.
This results in the formation of unpaired terraces.
If uplift continues for some time, incised meanders may form.
These are meanders that have been cut deeply into the valley floor.
Incised meanders are also known as entrenched meanders.
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Sometimes this measure/unit is known as cumecs.
A river’s regime is shown on a graph called a hydrograph.
A hydrograph shows the discharge of a river as well as total rainfall in the river’s basin/catchment area
over a period of time, before, during and after the storm.
It allows for a relationship between the rainfall falling in a river’s catchment area and the river’s
discharge.
Such information can be used to, for example, predict the risk of flooding in a given area after a storm
event.
Hydrograph
Characteristics of a hydrograph
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The same is also true of rivers that pass through areas that experience snow for example the Nile’s
famed floods are due to snow melting in the Kilimanjaro mountains resulting in peak discharge even in
the hot dry months as water moves from snow storage e.g. glaciers into the streams.
Geology for example rivers that flow through porous and pervious rocks tend to have smaller
peaks/small changes in discharge as opposed to rivers in granite (non-porous and impervious) rocks.
Human activities for example urbanisation results in more impervious surfaces and very high peaks,
short lag time and higher peaks (differences between the lowest and highest discharge.)
Drainage basin
The term drainage basin refers to an area of land drained by a river and its tributaries (river system).
It includes water found in the water table and surface run-off.
The drainage basin is also known as catchment area among an assortment of terms.
There is an imaginary line separating drainage basins called a watershed.
Usually, the watershed is a ridge of high land for example mountains forming a boundary between two
adjacent drainage basins.
The point where a river begins is called the source. It is usually in the form of a lake or spring.
A confluence is the point where two rivers join.
A tributary is a stream or smaller river that joins a larger river.
The mouth is the point where a river enters the sea.
Drainage patterns
Drainage pattern is a term that refers to the way in which a river and its tributaries arrange themselves
in the drainage basin.
The drainage pattern evolves over a long period of time and is affected by such factors as the underlying
rock, the slope of the land, the existence or nonexistence of fault lines and tectonic movements.
The most common drainage patterns are: trellis, dendritic, radial, centripetal and parallel.
Trellis
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It is formed where streams join the main river at right angles.
The trellis pattern develops in areas of alternate hard and soft rocks.
The main river (also known as the consequent stream) follows the dip of the rocks down the slope after
an initial uplift.
The tributaries (also known as the subsequent streams) which develop along the soft rock join the main
stream at right angles.
These tributaries are at times joined by their own tributaries at more or less right angles.
Streams that flow against the dip of the rock strata are called obsequent streams.
In Zimbabwe Trellis drainage is found in the Chimanimani mounts.
Trellis drainage also occurs along fault lines and rectangular joints in eroded fold mount areas due to
headward erosion by streams.
Dendritic
The word dendritic comes from the Greek dendron meaning tree.
In dendritic drainage patterns the streams join one another in a shape that looks like the branches of a
tree.
These streams eventually end up as one big river (the trunk).
The tributaries join each other at acute angles.
It is commonly found in areas with a uniform rock structure resulting in uniform erosion.
It is also found in areas which have gentle slopes.
Radial
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Is formed where streams drain from a central highland in all directions.
It is also known as centrifugal and divergent drainage.
It is common in areas with conical hills and/or domes for example volcanic cones and other conical
landforms.
Streams radiating from these areas can later end up forming other patterns as the flow downstream and
meet up with other tributaries.
In Zimbabwe these type of drainage pattern is found in areas that have granite domes still covered by
soil.
Convergent Drainage
o Is found in areas where rivers drain towards a central inland lake, swamp or depression.
o It is in essence an inland drainage system e.g. as in the case of the Dead Sea.
o It is common in inland depressions such as faulted intermountain (between mountains) basins, calderas
as well as in arid and semi-arid areas.
Parallel
Rivers and tributaries flow downhill together in a more or less parallel pattern.
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It is the simplest and most basic drainage pattern.
It occurs on newly uplifted land or land that is gently sloping allowing rivers and tributaries to flow in
parallel channels.
Examples include the Zambezi and its tributaries.
Kariba project in Zimbabwe, Cabora Bassa in Mozambique, Kafue river project in Zambia, Volta in
Ghana, Kaini in Nigeria and Orange River Project in South Africa.
Zimbabwe has many inland water bodies including Mutirikwi and Lake Kariba on the Zambezi river.
Kariba project
Advantages
a) Provides water for domestic and industrial purposes.
b) Fishing and tourist centre.
c) Hydro-electric power generating.
d) Irrigation.
Hot Deserts
The largest arid and semi-arid deserts occur between latitudes 15° and 30° North and South of the
equator.
Most of these deserts are located on the western sides of the continental masses on which they lie.
They occur within the Trade wind belt where the winds are off-shore.
- Off-shore winds are those winds that blow from the shore towards the ocean.
- These winds (Trade winds) tend to be dry after loosing their moisture as they journey across the
eastern side of contents.
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- Although west coasts have on-shore winds (winds from the ocean towards the land) blowing towards
them, they rarely bring rain.
- This is because the onshore winds meet with cold currents that blow parallel to coast lines (e.g. the
Cold Benguela current in the case of the Kalahari and the Cold Angola current in the case of the
Namib desert) this causes the moisture within the on-shore winds to condense and form mist, fog
and light rain before the winds reach the coast.
Most of the winds that blow across deserts are land winds which are dry/contain little moisture and
therefore do not result in any form of precipitation.
Some deserts as the Arizona desert are far from oceans, moisture from oceans is exhausted in the form
of rainfall in other areas before it reaches these deserts since they are further in the interior.
Some deserts such as the Gobi Desert, are located in rain shadow areas because they are in depressions
or basins.
Since they are on the leeward side of mountains where warm dry air is sinking they tend to receive little
to no rainfall.
In addition to this the relative humidity of the air mass falls resulting in high evapotranspiration rates
thus exacerbating the aridity of deserts while increasing their temperature.
The Kalahari and Sahara deserts are also located on the rain shadow side of major mountains.
In Zimbabwe areas like Save valley and major parts of Matabeleland are hot and receive very little
rainfall, droughts are frequent and may eventually become deserts.
Some deserts are located in the sub-tropical high pressure zone 30° North and South of the equator
which means winds tend to blow from these areas and dry warm air is sinking creating permanent high
pressure belts.
In some areas as the Patagonian Desert cool off-shore currents prevent local on-shore winds from
bringing in rain.
Most Hot Deserts are increasing in area in a process called desertification.
Human action sometimes contribute to desertification so in some ways deserts are a man-made feature.
Climate change has also resulted in changes in local rainfall patterns with increased incidence of
droughts in places like Somalia where rainfall might not fall for years on end.
Wind action
Wind action in deserts are also known as aeolian processes.
Wind is responsible for eroding, transporting and depositing materials in deserts.
Wind erosion
Wind is a process where the wind detaches soil particles from the land surface and transports them by
its force along the surface of the ground.
Erosion
Wind erosion involves three main processes: deflation, abrasion and attrition.
a) Deflation
- This is the progressive removal of fine material by wind leaving reg landscapes behind.
- By blowing away sand and other rock waste, the wind lowers the desert surface producing depressions
known as closed depressions or deflation hollows.
- Because the finer material is composed of smaller particles, it is lifted off and carried away by the force
of the wind.
- The deflation process provides the supply of sand used to build up sand dunes in other parts of the
desert.
-
b) Abrasion
- is the sandblasting action produced by materials during saltation as they are transported by wind.
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- This process smooths, pits, polishes and wears away rocks that are close to the ground.
- Since sand particles cannot be lifted up very high off the ground the zone of maximum erosion tends to
be within about 1 meter from the desert surface.
- This sometimes results in undercutting of effects on rocks.
- Large rocks are polished on their windward sides and rocks that are not uniform like granite are turned
into spongy, pitted, rough surfaces due to some minerals being softer than others.
- Pebbles and small rocks are shaped into ventifacts with polished windward sides. see diagram above.
c) Attrition
- Is the process by which large rock particles roll and rub against each other and wear away.
- This happens during the wind transportation processes.
- This process produces sand particles that are rounded into particles about the size of millet seeds.
Rock pedestals
Wind abrasion attacks rock masses and
sculptures them into strange shapes.
Yardang
Develops when bands of hand and soft rock
lie parallel to prevailing winds, wind abrasion
Zeugen produces a ridge and a furrow e.g. Salah in
Algeria.
Wind abrasion turns a rock surface with layers
of horizontal resistant rock underlain a non-
resistant rock into a ridge and furrow.
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Landforms by wind deposition Although they take many shapes, there are
Sand dunes two common types of dunes: Barchan and Seif
As soon as wind velocity drops wind dunes.
deposition occurs.
The heaviest material is deposited first while Barchan
the finer material and dust is carried further
before being dropped.
As a result loess (which consists of fine
particles) is sometimes deposited thousands
of kilometers from deserts.
Large mounds of sand result from sand
depositions within the desert.
These result in the formation of erg
landscapes such as those found in the Sahara.
Three major types of features result from wind
deposition and form part of the erg landscape:
sand ripples, barchan dunes and seif dunes.
A barchan dune is a small crescent shaped
dune.
Sand ripples
It has a height can range from a few meters to
about 30 meters in height and it can be 400
meters wide.
They lie at right angles to the prevailing wind.
It has its “horns” pointing downwind.
They usually form around an obstacle such as
These are small wave-like features which a rock, piece of vegetation or even a dead
develop on sand which move easily. animal.
They range from a few centimeters to about a As the mound, which is wind ward grows due
meter in height to continued sand depositions,
They are often temporary and suffer Its leading edges are slowly carried forward in
destruction when the wind changes direction. a downwind direction.
The windward slope of the dune is gentle.
Sand Dunes The downwind side is steep and slightly
curved.
This is caused by eddies that are set up by the
prevailing wind.
A barchan dune moves as grains of sand are
moved up the windward slope to fall onto the
leeward side.
These are hills of sand which are found in a
They can occur both singly or in groups.
variety of shape, size and direction.
Dunes develop when sand grains moved by
saltation and surface creep are deposited Seif dunes
(remember suspension material forms loess
which is deposited outside deserts).
Some dunes, but not all, form around
obstacles such as trees, bushes, rocks, a small
hill or even a dead animal.
Most dunes form on areas that are flat and
sandy rather than those areas that are rocky
and uneven.
Dunes vary in size from a few meters to over
a 100 meters in height. Are also known as transverse dunes, linear
dunes.
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They are ridge-shaped with steep sides and lie In deserts the wind erodes loose material from
parallel to the prevailing wind. flat areas which have, uncemented sediments
They are also formed and appear parallel to such as those occurring in tropical deserts.
each other. Deflation hollows develop in areas where the
A seif dune has a sharp crest which may be a transported materials is deposited.
100 meters in height and they can stretch for As already mentioned deposition occurs when
up to 150 kilometers in length. the wind meets with an impediment.
They are separated by flat corridors which are Deflation hollows are usually formed on
between 25 and 400 meters wide. surfaces patches where the protective
These corridors are swept clear of sand by the vegetative cover has been lost for example
prevailing wind. due to human activities or periods of extended
Eddies blow up against the sides of dunes and droughts.
drop deposit sand that is added to the dunes. Since that portion becomes unprotected, the
They usually develop from small sand ridges. wind deflates and scours continuously at
They slowly move forward in the direction of relatively unconsolidated material,
the prevailing wind as they move forward. The material is deposited on the edges of the
They feature in parts of the Namib Desert and hollow that are still protected by vegetation
the Sahara Deserts as well as other deserts. such as marram grass.
The removal of the fine particles the lowering
Deflation hollows of the landform leads to the formation of a
depression.
An example is the Qattara Depression
Sometimes water that falls in these depression
hollows during freak storms collects to form
pools in the midst of deserts providing an
essential source of water for local ecosystems,
animals and humans and their activities.
If an area is eroded down to the water table,
Are also known as closed hollows or blowouts further deflation is prevented unless the water
These are enclosed depressions caused by table is also lowered by evaporation.
wind erosion.
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Some oases in the Sahara were formed in this manner and may be below sea level.
Dunes are made from sand that is deposited at the leeward side of the wind.
Some deflation hollows may be formed in part due to the presence of faults within the rocks which are
exploited and widened by weathering and the regolith removed by wind erosion.
Note: all oasis are formed by deflation some are naturally occurring springs and some result as a result
of freak storms and the underlying geological rocks limiting the amount of infiltration.
Water action
Water action in deserts can be divided into three:
freak storms or rain that falls sometimes in semi-arid regions, dew which plays formed as a result of
temperatures falling below dew point at night in deserts and play an important role in chemical
weathering, water action in deserts as a result of past pluvial periods.
Various landforms result from water erosion and deposition in deserts viz: Wadis, Mesas and Buttes,
Bahadas, Playas
Water action
In most deserts no rain does not fall for several years.
When it does it comes in the form of unexpected and infrequent downpours.
Therefore despite the low rainfall totals (about 250mm per annum), water is still a dominant agent of
erosion and deposition.
This is especially true in semi-arid deserts like the Kalahari where rain falls more frequently.
Dew also forms in deserts where temperatures, due to relatively little cover resulting in temperatures
falling below dew point, is also found in deserts where it plays an important role in chemical weathering.
The infrequent but violent thunderstorms result in rushing torrents in steep slopes and to sheet floods
on gentle slopes
The run-off is more pronounced due to the relative lack of vegetation in desert landscapes.
The run-off on steep slopes is usually in the form of rills/shallow grooves which link up to form gullies.
These lead in turn to wadis/chebkas
During these storms water may flow in these wadis as flash floods and as they progress and carry more
and more materials they may turn into mud flows.
The mud is later deposited and forms features known as alluvial fans.
Wadis / canyon
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As the water dissipates after the end of the
storm and when it looses its energy upon
reaching less steep slopes the alluvium is
deposited to form fan shaped features at the
base of the piedmont zone.
Bahada
A depositional feature see above.
Knickpoint
A sharp change in profile that marks the
transition from the mountain front into a
pediment.
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It is the gentle slope that starts at the
knickpoint at the foot of the mountain.
This may be made out of bare rock or it can
be covered in alluvium deposited during
floods
Peripediment
It is made up of deposited material washed
across the pediment.
The peri pediment is a depositional feature
that is formed in the same way as bajadas but
it is larger.
Playas
These are sometimes known as inland
drainage basins.
Due to the fact that there are no permanent
drainage patterns in deserts any rain that falls
either evaporates or infiltrates into the soil or
runs off and drains into basins.
Basins are depressions.
When rain falls temporary rivers that flow in
canyons/ bahadas are formed and these may
eventually drain in a basin/depression.
These rivers form lakes in these depressions.
When these lakes dry up due to evaporation
they are turned into salt flats.
These temporary lakes and salt flats are
known as playas or sebkhas.
Examples of these can be found in the Sahara
desert.
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Human activity in deserts
Desertification
Desertification refers to the spread of desert conditions for example resulting in aridity or semi-arid
conditions and scant vegetation cover in the encroached area.
Desertification is therefore the spread of deserts as well as a reduction in the biological productivity of
a given piece of land.
It is also attributed to a process by which previously productive land turns into a desert like land and its
agricultural productiveness drops by ten percent or more due to natural and human factors.
A more comprehensive definition might define desertification as an environmental degradation process
brought about by both natural causes (e.g. chronic droughts) and excessive human activities (such as
climate change and deforestation) resulting in the fall in productivity of a given piece of land and the
spread of desert like conditions to the affected piece of land.
Climate change for example a reduction in the amount of rainfall received at a given area or increases
in evapotranspiration rates can lead to desertification.
The El Nino effect resulting in droughts.
Acid rain leads to the reduction of land productivity.
A land’s distance from the sea.
Continental drift for example most of the Sahara desert enjoyed pluvial periods during the so called
Quaternary era when the African plate was further south that it currently is and the Sahara region
occupied the latitudes currently occupied by the present day Savannah regions.
Human factors
Deforestation as people cut down trees for use as firewood, thatching, making furniture and other
industrial and domestic uses.
The clearing of land for agricultural use.
Overgrazing for example in the Sahel region.
Overpopulation as more population increases are not matched with increases in resources.
Expansion of human settlements such as towns and land is cleared for industrial and residential use.
Mining activities for example open cast mining and oil mining which leads to oil spills and destruction
of vegetation.
Salinisation which makes soils less fertile and makes vegetation growth impossible.
Effects of desertification
A reduction in vegetative cover due to deforestation and drought.
Barren sandy soils and sometimes soil hardening.
Increased surface runoff due to reduced vegetative cover resulting in the formation of gullies and
dongas.
Reduced soil fertility.
Reduced productive capacity of agricultural land.
Reduced land carrying capacity.
Death of livestock as a result of water and pasture shortage.
Water and pasture shortages.
Famine and starvation.
Reduction in annual rainfall and persistent droughts.
Solutions
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Afforestation that is planting trees where none previously existed.
Fallowing-allowing fields to fallow instead of growing crops on them continuously.
Legislation-passing laws that favour conservative farming methods and practices and penalises those
who do not follow the practices.
Educating people about the impact of poor farming methods and schooling them on the best farming
methods available to them.
Planting trees lines for example gum trees to act as wind breaks and lessen the impact of wind erosion.
Dam construction-for use in irrigation schemes and to provide alternative hydro-electric energy instead
of relying on firewood.
Practice irrigation for example using oases and rivers such as the Nile river.
Limit settlements near water sources such as oases.
Construct contours to conserve land and lessen the effects of erosion.
Terracing to lessen the impact of erosion.
Paddocking to implement controlled grazing and prevent overgrazing.
Practice crop rotation.
Create sand embankments.
Fencing to protect forests.
Grow drought resistant crops such as sorghum or practice activities such as extensive cattle ranching
that put less pressure on pastures.
Use alternative sources of fuel instead of firewood for example LP Gas.
Case Study
Example of desertification (Sahel Region)
The Sahel is the semi-arid transition region between the Sahara desert to the north and wetter regions
of equatorial Africa to the south.
It extends from the Atlantic in the west to the Indian Ocean in the east.
Its annual rainfall varies widely from year to year, and the land consists of stabilized ancient sand seas
is one of the poorest and most environmentally degraded areas of the world.
It forms a boundary between the Sahara and the wetter parts of Africa.
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The Sahara desert is slowly encroaching on Sahel land due to overpopulation and overgrazing,
persistent droughts, erratic rainfall and climate change.
The area has been plagued by persistent droughts.
The drought was partly caused by natural causes in the form of climate change.
The harmattan winds that affect the area are dry because they come from the Atlas mountains.
Human activities have also contributed to the desertification in the area.
The people of the region practice Nomadic pastoralism, moving from place to place looking for fresh
pastures.
This movement has caused deforestation and overgrazing as more and more animals grazed repeatedly
on the same piece of land.
This resulted in the degradation of the land whose productivity decreased.
This meant that less productive land would be available while the number of animals kept and keeps
increasing worsening the situation.
Reaction
UNESCO held a meeting in Nairobi Kenya to alert the world about the disaster.
They also provided food and water to the affected people.
Other international relief agencies such as UNICEF and the Red Cross were involved.
Concerted efforts have also been made to educate the people of Sahel on the effects overpopulation,
overgrazing and conservation methods.
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BIOTIC STUDIES
BIOTIC STUDIES (ECOSYSTEM)
Ecosystem refers to the links or relationships or interactions between living organisms (biotic) and non-
living organisms (abiotic) in relation to the environment. Ecosystems vary in size; examples include the
equatorial, the Savanna and the hot desert ecosystem.
The biotic component.-this is the living component which include all the living organisms ie, plants and
animals.
The abiotic component- this is the non- living component which include the soil, sunlight, temperature,
precipitation and water or moisture.
Key processes in ecosystems include the capture of light energy and carbon through phosyntesis, the
transfer of carbon and energy through food webs abd the release of nutrients and carbon through
decomposition.
The living components can be producers, consumrs or converters/decomposers and these links with the
abiotic elements to form a food chain.
ABIOTIC
ELEMENTS
CONVERTERS
PRODUCERS
DECOPMOSERS
CONSUMERS
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Producers (Autotrophs)
These are plants or grass which manufacture their own food through the process of photosynthesis,-(plants
capture energy from light and use it to combine carbon dioxide and water to produce carbohydrates and
oxygen)
Consumers
These are animals that feed on the producers as food. Consumers can be put into two groups
Primary consumers/ herbivores- these are animals that feed on grass/plants only eg, zebras, and guzelles.
Secondary consumers/ carnivores-these are animals that feed on other animals. They also include
omnivores –these are animals that feed on both plants and animals.
Decomposers /Converters
These are bacteria/fungi that break plant and animal tissures back to nutients for use by plants (end of the
cycle).
Energy as an input is provided by the sun. Plants convert solar energy into chemical energy through
photosythesis. When animals feed on plants the chemical energy is transfered into the animal as heat energy
and forms a continuous chain.
PRODUCERS/
SUN'S ENERGY CONSUMERS DECOMPOSERS
AUTOTROPHSAUT
Once energy is lost it cannot be recycled. Energy is lost at each stage or trophic level and it decreases as it
flows from one level to the next as shown on the energy diagram below. Plants get nutrients from the soil.
These are stored in the plant tissues such as leaves, stems and flowers. When tissues fall to the ground they
decompose together with dead insects, animals and animal waste. These are then in cooperated into the soil
by earth worms and rainfall and transferred into nutrients. Some nutrients may be lost through runoff as
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litter and some through leaching. Minerals may be added into the soil to become nutrients through the
weathering of parent rock.
Location
Mainly found between 00 _ 100 south or north of the equator .Examples include the Congo Basin in Africa,
the Amazon basin insouth America and South East of Asia. (Brazil, Zaire and Indonesia)
Temperature characteristics
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Warm to hot temperature all year round with an average of around 25 0c. Temperature is fairly uniform
throughout the year. There is very litle temperature variation. Temperature range is between 10 0c - 30c.
High temperature is due to the position of the sun in relation to the equatorial region ie the equator.
Rainfall characteristics
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The leaves are broad and ever green to allow photosynthesis to take place.
The vegetation is dominated by hard wood.
Leached soils due to high rainfall and quick up take of nutrients by plants.
Humus content is low because of rapid breakdown and up take by plants as well as leaching.
Some is consumed by small creatures such as ants and termites. Bacteria activity is very high due
to high temperature and precipitation.
Soils are light in colour due to low humus content.
Decomposition is very fast due to high active nature of bacteria.
There is a wide variety of birds and animals. Tree climbing animals are more dominant.
Nutrient cycling in the tropical rainforest ecosystem.
Tropical rain forest areas include Amazon Basin, coast West of Africa, Congo basin and South East
Asia.
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Deforestation is the cutting down of trees without replacing them (Chenje et al 1998) or permanent
destruction of indigenous forests and woodlands.
Causes
Slash and burn (shifting cultivation)-the local people clear land in order to grow crops.
Road building-vegetation has been cleared to create roads to access the forests. This has caused
increased destruction as the forests become more accessible eg. Trans- Amazon Highway.
Commercial logging – commercial exploitation of wood is the major cause for forest destruction
especially in South America, East Asia and Africa. Landless people enter the land that has been
previously logged for settlement and farming.
Cattle ranching – contributes to vegetation destruction in Central and Southern America. In Central
America two thirds of lowland tropical forest has been turned into pasture since 1950.
Hydroelectric power – plenty of water has led to the development of HEP stations and this has
contributed to forest destruction.
Farming -The government in Brazil has cleared large areas of the Amazon Rain forest and
encouraged people to move there. Farmers stay in the same area but soil becomes infertile and nothing
will grow (why?)
Mining -Mining of iron ore, gold e.t.c. has led to destruction of rainforest e.g. The Amazon.
Effects of deforestation
Ecosystem- the ecosystem is affected, the nutrient cycling process is affected because nutrients comes
from the plants and trees ie 80% of the nutrients come from the plants and trees and leaving 20% in
the soil. The rainforest will never fully recover. - Wildlife and plant life is reduced. (Upset the
ecosystem)
Soil erosion- Removal of vegetation left the soil exposed and this is eroded and washed away-
Removal of the top soil means little vegetation will grow.
-Soil erosion will lead to: siltation of rivers.
-Flooding as soil is deposited in rivers bed reducing its capacity to hold more water.
- Lost of natural resource for ever.
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It has adverse impacts on bio sequestration of atmospheric carbon dioxide. Bio sequestration is the
capture and storage of the atmospheric greenhouse gas carbon dioxide by biological processes.
Climate Change.
Solutions
SAVANNA ECOSYSTEM
LOCATION
Found between latitudes 5O-15O north and south off the equator
It is mainly found between the Tropical rainforest and the hot desert ecosystems.
Examples include parts of Central Africa e.g. Kenya, Southern parts of Africa e.g. Zimbabwe,
Zambia, the North and East of South America (Brazil).
CHARACTERISTICS
TEMPERATURE
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Vegetation
The vegetation is characterised by tall grass and short scattered trees. From savanna towards the equator
vegetation increases in size and density and desert-wards vegetation merges into small shrubs and thorny
bushes.
Trees and plants are deciduous- they shed all their leaves during the long dry season (winter) to
reduce loss of water through transpiration.
Trees have long tap roots to search for ground water deep underground i.e. the water table.
Trees are umbrella shaped to reduce loss of water through evaporation from the root surface.
Trees have broad trunks e.g. Baobab to store excess water.
The trees have thick, hard barks to protect themselves from fires (fire resistant)
The grass remains dormant during the dry season.
Trees are thorny with small leaves to minimize loss of water through transpiration.
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SOIL CHARACTERISTICS AND NUTRIENT CYCLING
ANIMALS
It supports large number of animals due to plenty of grass. This has led to the development of
ecotourism.
Large antelopes, elephant e.t.c.
Plenty of wildlife due to plenty of food, plenty of space to move and to hide, plenty off surface
water.
Vegetation
Due to lack of rainfall and extreme high temperature areas are devoid of vegetation
Vegetation consit of cactus/euphobia
They have succulent leaves to store water during the long hot dry climate.
Trees are thorns – to reduce evapotransipiration and for protection from grazing animals.
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Fewer plants due to hot dry climate and poor soils.
Animals
Burrowing animals mainly lizards which can hide in holes during the day when temperature is
high and become active at night.
Limted wildlife due to scacity of food and water.
SOILS
Soil is the uppermost layer of earth’s crust, which supports growth of plants.
Soil is a renewable as well as non-renewable resource.
Soil is renewable because its productivity can be maintained with fertilizers and manures rich in humus.
If the soil has been removed from a certain place by erosion, it is practically non-renewable because
formation of new soil may take hundreds and thousands of years.
Soil formation
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1. Regolith - Loose broken material due to weathering of rock or deposition of alluvium, drift loess and
volcanic material.
2. Formation of topsoil by adding water, gasses, living organisms, and decayed organic matter (humus).
Five major factors of soil formation - Time, parent materials, climate, living organisms, topography
Components of soil - mineral matter (45%), inorganic matter (5%), soil water (25%), soil air (25%).
Inorganic Matter - Provide minerals required for plant growth
Soil Water - Derived from rainfall and is important for regulating temperature, dissolving nutrients.
Soil Air - Plants and animals gain oxygen for metabolism from soil air
Characteristics of soil are influenced by - Vegetation, parent rock, climate and weathering
Properties of soil - Soil profile, soil depth, soil colour, soil texture, soil porosity, soil structure.
a. Soil Profile - A vertical cross-section of the soil showing its horizons.
b. Soil Depth - Varying properties depending on the maturity of the soil and nature of rocks below.
c. Soil Colour - Colour is determined by mineralogical composition of the soil.
d. Soil Texture - The degree of coarseness or fineness of a soil.
e. Soil Porosity - Total volume of pores or empty spaces between particles of soil material.
f. Soil Structure - Refers to the arrangement of soil particles
Factors influencing soil fertility - Presence of mineral plant nutrients, presence of water, presence of
air, soil pH, soil, presence of colloids, presence of organisms
Loss of soil fertility - Leaching, over-cultivation, monoculture, soil pollution, soil erosion, mass
wasting, loss of water in the soil
Podzol - The group of soils which occur mostly in moist cool temperate climates.
Clay Soil - Is a naturally occurring material composed primarily of fine-grained minerals
Laterites (Red Lateric Soil) - Are soil types rich in iron (causing red from oxidation) and aluminum,
formed in hot and wet tropical areas.
Loam - Is soil composed of sand, silt, and clay in relatively even concentration.
Leaching - Is the loss of plant nutrients from the soil, contributes to groundwater contamination.
Humus - Refers to any organic matter that has reached a point of stability, where it will break down no
further and might, if conditions do not change, remain essentially as it is for centuries, if not millennia
Types of soil
Azonal, intrazonal, zonal
Azonal Soil
- Are without well-developed characteristics due either to their youth or to some condition of relief or
parent material which prevent soil development, Soils forming in recent eolian, alluvial and colluvial
deposits are azonal
Intrazonal Soil
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- Have well defined soil profile characteristics that reflect the dominant influence of some factor of relief
or parent material over the classic zonal effects of climate and vegetation
Zonal Soil
- Soils with clearly distinguishable horizons which occur in definite regions of climate and vegetation
Erosion literally means “to wear away” or removal and detachment of soil from the earth`s surface is
called soil erosion.
Natural Causes
Natural agents like wind and water – high velocity winds and running water over lands.
Conservation of Soil
Soil conservation means checking soil erosion and improving soil fertility by adopting various methods.
Maintenance of soil fertility by adding manure and fertilizers as by rotation of crop.
Control on grazing through paddock system.
Reforestation.
Terracing - dividing a slope into several flat fields to control rapid run of water.
Contour ploughing.
Ploughing across slopes.
DISCUSS:
# Discuss the human effects on the savannah and Hot desert ecosystems.
# Discuss how the land reform programme in Zimbabwe affected the Savannah ecosystem.
# suggest measures to deal with the effects of the land- reform programme on the Savannah ecosystem in
Zimbabwe.
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These plants are usually smaller in order to prevent water loss from surfaces.
They have little or no leaves, but, instead have thorns.
The leaves of some plants are fleshy as they contain aqueous tissue.
Some plants have very long roots to get moisture deep under the ground.
Some plants remain dormant during dry periods and come to life when water is available.
Read more at Buzzle: http://www.buzzle.com/articles/desert-vegetation.html
Wetlands
The Environmental Management Act (Cap 20; 27) define wetlands as : “Areas of marsh, fen, peat land or
water, whether natural or artificial, permanent or temporary, with water that is static or flowing, fresh,
brackish or salt, including riparian land adjacent to the wetland”.
In Zimbabwe, wetlands cover approximately 4.6 percent of the land; vleis are the most dominant as
they cover 3.6 percent of the land area and it is estimated that there are 1 262 000 hectares of wetlands.
In Zimbabwe wetlands are also known as Matoro (Shona), Mapani (Shona) and Amaxhaphozi
(Ndebele).
Zimbabwe is a Signatory to the Ramsar Convention on Wetlands of 1971 and has domesticated
provisions for the protection of wetlands under the Environmental Management Act (Cap 20;27),
Statutory Instrument 7 of 2007 on Environmental Management (Environmental Impact Assessment and
Ecosystems Protection) and Regulations and Government Gazette 380 of 2013.
The Ramsar Convention embodies commitments by member countries to maintain the ecological
character of wetlands and to plan for the “wise use” or sustainable use of all of the wetlands in their
territories.
In Zimbabwe seven sites have been designated as Ramsar protected wetlands and these are: Victoria
Falls, Driefontein, Middle Zambezi/Mana Pools, Lake Chivero, Monavale Vlei, Chinhoyi Caves and
Cleverland Dam.
The Government Gazette 380 of 2013 declares 26 wetlands in Harare as protected areas. These include
Mabvuku, Honeydew, Balantayne Park etc.
Importance
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Causes of Wetland degradation
Agricultural activities.
Drilling of boreholes.
Commercial and residential development; road construction; impoundment; resource extraction;
industrial siting, processes, and waste; dredge disposal; care and cultivation of forest trees (silviculture);
and mosquito control through drainage, channelization and use of toxic pesticides.
Measures
Plant native species to maintain the natural balance of the wetland. The plants in and around a wetland
trap and filter out sediments and chemical pollutants and aid in groundwater recharge by retaining runoff
waters;
Direct storm water into wetlands especially in urban areas because they supply much of the water
necessary to maintain wetlands.
Maintain a green belt around the wetland.
Fence the wetland against animals that may destroy vegetation.
Do not cut down trees and clear grass.
Do not introduce non-native (exotic) plants as they damage or ruin ecosystems e.g. gum trees drain a
lot of water.
Use organic manure instead of fertilizers and pesticides.
Avoid dumping waste on wetlands, this causes land and water pollution.
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NATURAL RESOURCE STUDIES
Non-renewable energy: Energy that cannot be reproduced in the time that it takes to consume it e.g. coal.
Renewable energy: Energy that is naturally occurring and potentially infinite.
Fossil fuels: Any combustible organic matter that is made from the remains of former flora and fauna.
Raw material: Any unprocessed material.
Global Energy
As the world's population continues to grow and as peoples level of development continues to grow, so
does the demand for energy. In traditional less developed societies the main source of energy tends to
be fuelwood. Fuelwood can be used for heating, cooking and even scaring away wild animals.
As countries begin to develop they can begin to afford to buy raw materials and to build power stations.
Most commonly fossil fuels are burned because the technology exists and at the moment they are widely
available.
However, as countries develop further their sources of energy may change again. They will probably
still be heavily dependent on fossil fuels, but will begin to use more renewable energy and probably
more nuclear. The reasons for the change include:
- Greater concern for the environment.t
- Rising prices of fossil fuels.
- Aim to reduce reliance on fossil fuel exporting countries.
- Improvements in renewable technology.
- The hope of developing and selling renewable technology
- Better technology and increased stability allowing nuclear development
Type of non-renewable energy (fossil fuel)
Coal
Advantages
1. Energy production using coal can be increased or decreased according to demand
2. The technology to burn coal to generate electricity already exists
Disadvantages
1. Coal is finite so will eventually run out.
2. Many existing reserves are becoming harder to extract or are in environmentally sensitive areas
3. Coal releases large amounts of greenhouses gases when burnt
4. Mining deep underground coal is very dangerous
5. Coal is very bulky and expensive to transport around the world
Thermal Power
Fuel such as coal, oil and natural gas can be used to heat water in huge boilers to produce steam.
The steam at high pressure turns turbines.
Turbines turn generators to produce electricity.
E.g. Hwange and Munyati power station.
Locational factors
Near fuel source e.g. S.E Lowveld uses baggase from sugarcane.
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Market based.
Flat land.
Near large rivers or source of sufficient water.
Transport.
Oil
Advantages
1. Energy production using oil can be increased or decreased according to demand
2. The technology to burn oil to generate electricity already exists
3. Technology is improving to extract deeper reserves as well oil in tar sands (Canada).
Disadvantages
1. Oil is finite so will eventually run out
2. A lot of oil is located in politically unstable countries or environmentally sensitive areas e.g. Libya and
Iraq.
3. Oil can cause widespread pollution when spilt
4. Oil releases large amounts of greenhouse gases when burnt
5. Oil is vulnerable to large scale changes in its price
6. The production of oil refineries is expensive
Gas
Advantages
1. Energy production using gas can be increased or decreased according to demand
2. The technology to burn gas to generate electricity already exists
Disadvantages
1. Burning gas releases less greenhouses gases then coal and oil
2. It is now possible to compress gas and transport it more easily.
3. Gas is finite so will eventually run out
4. A lot of gas is located in politically unstable countries or environmentally sensitive areas.
5. Gas is vulnerable to leaks and explosions
Type of Renewable Energy
Solar: Using the power of the sun to heat water or generate electricity.
Advantages
1. It is a clean form of energy
2. It is an infinite resource
3. Panels can be used locally e.g. on top of someone`s house.
4. It can be used to heat water and generate electricity.
Disadvantages
1. It is expensive to make solar panels.
2. The sun does not shine all the time.
3. Not every country gets adequate levels of sun.
4. They can't be used at night.
5. It is hard store surplus energy.
6. Supply does not always equal demand.
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Wind
Using the power of the wind to drive a turbine to generate electricity.
1. Advantages
2. It is a clean form of energy
3. It is an infinite resource
4. It can be used on a local scale e.g. in your back garden
5. Technology is proven
6. They can be placed at sea on in mountains away from settlements
Disadvantages
1. Visual pollution.
2. Noise pollution.
3. Wind is unreliable.
4. They are expensive to install, especially offshore.
5. It is hard to store surplus energy.
6. They have to be turned off in very strong winds.
Tidal
Using the incoming and outgoing motion of the tide to generate electricity.
Advantages
1. It is a clean form of energy.
2. It is an infinite resource, tides happen twice a day.
3. Ideal for island countries.
Disadvantages
1. It can block important shipping routes
2. May interfere with some animals e.g. sea otters and seals
3. Limited number of sites
4. Useless for landlocked countries
5. High start up costs. The technology is still being developed
6. May be damaged by tropical storms
Wave
Using the motion of waves to generate electricity.
Advantages
1. It is a clean form of energy
2. It is an infinite resource
3. Ideal for island countries.
Disadvantages
1. Again it can block shipping routes and interfere with animals.
2. Again not suitable for landlocked countries.
3. The strength of waves can vary
4. May be damaged by tropical storms
5. The technology is still being developed.
HEP (Hydroelectric power)
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Using the power of falling water in rivers to drive generators.
Advantages
1. It is a clean form of energy
2. It is finite as long as rivers are managed properly.
3. The built dam can also prevent flooding.
4. The reservoir behind the dam can be a store of water.
Disadvantages
1. Only a limited number of suitable rivers.
2. Can hamper navigation up and down river.
3. Reservoirs may force resettlement.
4. Migration patterns of animals may be disrupted.
5. Dams reduce the deposition of alluvium downstream.
6. Dams can flood large areas of land.
Hydro – electric power generation at Kariba
Water leaves the lake (head of water) at high pressure and goes through the penstocks ( concrete and
steel pipes).
The larger the depth of water, the more the pressure hence high electricity generation.
High speed water hits cups of turbines.
Turbines start spinning and rotating.
They in turn generators to which they are attached with pistons.
Generators produce electricity.
The water passes through surge chambers and return back to the river through trailrail pipes.
Electricity is transmitted to huge transformer which regulates the power .
Electricity is transmitted through cables to homes for use.
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A gorge and water falls – much water in the narrow valley, a large head of water at the falls, low cost
of construction, firm dam wall on hard rocks e.g Kariba gorge, Cabora Basa gorge in Mozambique.
Large perennial rivers for large volumes of water e.g. Zambezi river.
Space for dam construction and the scheme, thus why people have to be relocated to other areas.
Income since it`s expensive to erect the project.
Demand.
The use of biological matter to create energy. It is a renewable form of energy, but because the matter is
often burnt it still releases greenhouse gases.
Advantages
1. It is a renewable form of energy as long as people replant crops.
2. It is cheap and the resources can be grown locally
Disadvantages
1. It can still release greenhouse gases.
2. Areas can be deforested to grow crops for energy generation.
3. If crops are used for energy production it can lead to an increase in food prices.
Geothermal
Geothermal uses thermal energy from the earth to heat water. The water can be used as a source of hot
water or the steam released can be used to drive turbines e.g. Nyanyadzi.
Advantages
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1. It is a clean renewable form of energy.
2. It is a finite resource.
3. Can be used to heat water and generate electricity.
4. Geothermal energy can be created constantly and is not dependent on the weather.
Disadvantages
1. Not every country has geothermal potential.
2. Installation and startup costs are expensive
3. Drilling can release harmful gases.
4. Geothermal activity can change which can make the production of energy harder
Nuclear Energy
Some people consider nuclear energy to be a renewable energy. However, because nuclear energy uses
uranium and uranium is non-renewable, then nuclear energy should also be considered to be non-renewable.
Although the first man-made reactor was first operated in 1942 in the US, the first electricity producing
nuclear power station was not completed until 1951.
It is estimated that nuclear power provides about 14% of the world's electricity (6% of its energy). Japan
(all nuclear reactors are temporarily closed after the Fukushima Disaster March 2011), US and France
combined account for about 50% of the world's nuclear power produced although are 439 nuclear power
stations in 31 countries.
Nuclear power has created widespread debate, because some people see it as a solution to declining fossil
fuels while others worry about the waste produced, the technology falling into the wrong hands and
accidents.
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Fuelwood is often the main source of energy because countries either can't afford to buy raw materials to
produce energy, don't have the technology or money to build and operate powers stations and certainly
don't have a national grid to distribute energy.
Problems include:
1. Deforestation.
2. Biodiversity loss (vegetation is removed and animals lose their home).
3. Desertification and reduced rainfall.
4. Increased soil erosion and increased sandstorms.
5. Increased time spent looking for wood.
6. Children taken out of school to look for wood.
7. Dangers of breathing in smoke inside houses.
8. Risk of fire within houses.
Impacts of Energy Crisis
Solutions
Developing alternative sources of energy e.g. solar, biomass, Geothermal and HEP.
Management and conservation of energy.
Encouraging industries to use coal which is slightly cheaper than petroleum.
Afforestation and reforestation programmes.
Education campaigns on how to conserve fuel.
Use of tsotso stove for wood.
Developing new thermal power stations in GOKWE NORTH.
Refurbishing KARIBA.
Management and Conservation of Energy
Management Measures
Conservation of Energy
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Conservation of energy is using available energy resources in the most effective manner to ensure there
isn`t wastage.
Conservation Measures
Physical Factors
Presence of Plankton
Large shoals of fish are found in shallow waters of lakes and seas where there is plenty of plankton.
They thrive where depth of waters less than 180 m deep because it is up to where suns rays can reach.
Relief
People in some countries engage in fishing due to mountainous landscape which hinders other economic
activities such as agriculture e.g. Japan, Norway and Alaska.
Climatic Conditions
In temperate regions there is more fish because there is cool waters which plankton requires to grow
while in tropical lands there is less fish due to high temperatures resulting in warm waters which hinders
plankton growth.
Human Factors
Supply of Labour
Fishing is intensively carried out in Europe, Asia and N. America due to labour availability as its labour
intensive.
Market
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Fishing is done extensively in highly populated and developed regions with a ready market because fish
is a perishable commodity e.g. in Norway, Japan, China, etc.
Capital
Fishing is extensively done in developed countries because they can afford huge sums of money
required for hiring labour force, buying fishing equipment and preservation facilities.
Technology
Rapid growth of fishing industry in developed countries is as a result of presence of advanced equipment
like large refrigerated ships, trawl nets, fish detecting equipment, etc.
Types of Fishing
Pelagic Fishing
- Catching of fish which live close to the surface e.g. mackerel, menhaden, herring, sardines and tuna.
- Best method to catch pelagic fish is drifting and seining.
Demersal Fishing
- Catching fish that live at the bottom of deep water bodies e.g. cod, haddock, Pollock and halibut.
- Methods are trawling and long lining.
Inshore Fishing
- Fishing close to the shores in shallow sheltered coastal waters and the lower stretches of rivers.
- Fish caught are shell fish, lobsters, prawns, shrimps and crabs.
- Methods involved are casting nets, hooks and line.
Methods of Fishing
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- The catch is relatively small.
Harpooning
Gill Nets
Using a sharpened arrow or stick to strike Fish. -Nets with mesh which lets only the head of a fish
- One fish is caught at a time. through and then traps it by the gills.
- Dangerous in waters infested with crocodiles -They can be swerved across or round the river on
and hippopotamuses the path of fish.
Modern Fishing Methods
Barrier Method
Seining
- Method is used to catch pelagic and migratory
fish which swim in shoals.
- A Bag like nets with small meshes (seine)
attached to two boats on each end is cast into the
sea.
- It`s kept open and held in position by floats on
top and weights at the bottom.
- Fish move towards the net and get trapped.
- The net is hauled over and fish emptied onto the
ship or the net is hauled to the shore (haul
Using Barriers made of reeds or sticks to catch seining).
fish in flood waters. - Leads to overfishing because it doesn`t
- Are placed on the downstream side of a flooded discriminate the ages of fish caught
region and when water levels drop the fishermen
scoop the fish. Trawling
Herbs
- Sprinkling crushed herbs in waters making fish
to become unconscious then the fishermen collect
fish from the river using hands.
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Mainly used to catch demersal fish. Line Fishing
- A bag shaped net is attached to a trawler (ship) -The method is used to catch demersal fish.
is is cast into deep waters - Fishing boats spread out long line with several
- The upper part is kept open by floats and lower baited hooks on them.
part kept down by weights. - Floats keep the lines suspended and also show
- The net is dragged by the trawler along the sea the fishermen where the lines are.
bed. - Baited hooks catch the fish as they compete to
- The trawl net sweeps in the fish. feed.
- The net is hauled into the trawler and the fish is - Hooks are drawn and fish unhooked and put in
emptied on board. refrigerated containers.
- Also catches immature fish.
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Southern Africa c. Agulhas Bank – mackerel, cape hake,
sardines, kingklip and herring.
a. Located in East coast of Southern Africa –
breams, hakes and herring.
Conditions
Broad continental shelf, warm agulhas currents
and cold Benuela currents, calm water, moderate
temperature, rich in fish food, ideal breeding
Conditions ground of variety fish species.
Warm Mozambique and Agulhas currents, poor
growth of plankton, poor fishing grounds and
narrow continental shelf.
Conditions
Washed by cold Benguela current which cools the
warm tropical waters hence favouring the growth
of plankton, rich in nutrients, rich fishing grounds
and ideal fishing harbours.
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Fresh Water Fisheries
- Found in inland in lakes, dams, rivers and ponds.
ZIMBABWE
Aquaculture
The farming of aquatic (water based) plants and animals e.g. mussels, fish and seaweed.
Lake Harvest Farm at Kariba
Advantages
Includes the development of tourist industry in the Eastern Highlands of Zimbabwe.
Provision of cheap protein food.
Source of income.
Allows recycling of wastes e.g. chicken droppings used as feeds.
Reduction of diseases such malaria and bilharzia as fish species feed on larvae.
Significance of the Fishing Industry in Zimbabwe
(a) A source of income to fishermen and traders when they sell their catch to co-operatives and customers
at a profit.
(b) Employment creation such as making and repairing of boats and officers and clerks of co-operatives.
(c) It is a tourist attraction and source of foreign exchange and revenue to the government.
(d) A source of protein and food because it`s a major dish to some communities.
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(e) Has led to development of industries such as those depending on fish as a raw material e.g. fertilizer
plants, for making cod liver oil, etc.
(f) A source of medicine whereby cod liver oil is used in alleviation of chest problems.
(g) Fish oil is used directly or indirectly as a source of cooking fat.
Management of fisheries refers to effective planning and control of fish resources and their habitats while
conservation of fisheries is careful use and protection of fish resources from overexploitation by people.
Management Measures
(a) Establishment of research stations to come up with fish species which can do well in various
conditions and know fish predators and separate them from fish.
(b) Educating people on the importance of fishing grounds and fish resources such as by advising farmers
not to cultivate near fishing grounds to prevent siltation and industrialists to treat wastes before disposing
them.
(c) Government inspecting inland water resources to ensure people don`t interfere with regular flow of
water through their activities.
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Conservation Measures
(a) Enact law banning of small meshed nets to prevent catching of immature fish.
(b) Improve transport infrastructure to enable exploitation of fishing grounds in remote areas in order to
reduce overexploitation of the few accessible fishing grounds.
(c) Fish farming to ensure fish caught in natural waters aren`t overexploited and depleted.
(d) Restocking overfished waters using fingerings from hatcheries or from overpopulated fishing grounds.
(e) Banning fishing temporarily whenever over fishing is detected to let fish to mature and breed.
(f) Licensing fishermen to regulate the rate at which fish are exploited to prevent their depletion.
Mining
Define the above term. [2]
Mining Methods
Is a method of extracting rock or minerals from the earth by their removal from an open pit.
The overburden is removed using large excavators and draglines.
Used to extract coal at Hwange, asbestos in Zvishavane.
Advantages
a. Causes deforestation.
b. Blasting destroys buildings and causes noise pollution.
c. Use of explosives harms miners.
d. Open cast leaves land scared.
Shaft Mining Method
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Is the method of excavating a vertical tunnel from the top down, where there is initially no access to the
bottom.
Used to extract deep seated ores over 50m deep.
Involves sinking of vertical or inclined shafts to the level of the seam.
Horizontal tunnels are built following the seam e.g. chrome in Shurugwi, coal at Hwange and gold in
Mazowe.
Advantages
a. There is less deforestation.
b. It allows extraction of deep seams.
Disadvantages
a. It is very expensive.
b. Flooding can be a danger to miners.
c. Cave ins and toxic gases are a great risk.
d. Deep mines can cause earth tremors.
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Adit / Drift
Used to extract minerals that are on the sides of mountains and river valleys.
Involves building of horizontal or inclined tunnels along the mineral seam.
Conveyor belts and railway lines are also built to facilitate the extraction of the ore.
Advantages
Disadvantages
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Factors affecting the exploitation of mineral resources
Answer:
-employment creation
-produce raw materials
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-support industries as a market
-foreign currency from exports
-development of infrastructure such as roads, railway line, recreational facilities, hospitals/clinics, schools
and houses
-improve living standards
-source of income
-skills transfer
Gold panning
Licencing of panners.
Enforcing environmental laws.
Education and training of panners on environmental friendly methods of mining.
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a lot of time needed for research on suitable tree species to be grown in that particular area
soils are sterile or they contain toxic acids which retard the growth of plants
Conservation of Mineral Resources and Protection of Resources and the Environment
Recycling.
Reuse.
Replace / use of alternative resources.
Modern technology in processing of ores to reduce loss.
Case Study: one non – renewable resource
- Copper deposits occur in an axil belt stretching from Zambia to Democratic Republic of Congo (DRC)
with mines from Nchanga, Mufulira to Ndola.
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- Occurs in seams of various depths such that both open and shaft mining are used.
- Factors that led to development of mining on the copper belt are labour from nearby countries e.g.
Zimbabwe, technology and capital, market, power supply and political stability.
Disadvantages
Forestry
Exotic plantations-these are extensive forest areas planted with imported tree verities like pine, wattle
and eucalyptus.
Indigenous forests-these are mainly found in reserves mainly locally found
-constant drought.
-strong winds.
-competition for land with other land uses e.g. fruit farming, tea, and coffee
-growth of population which leads to demand for settlement and crop farming
Classes of Forests
1. TROPICAL FORESTS
2. TEMPERATE DECIDUOUS FORESTS
3. CONIFEROUS FORESTS
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-new technology which ensures maximum utilisation of wood fuel
-substitution of wood fuel for other uses e.g. Solar and biogas
-resettlement
-recycling
-population control
-CAMPFIRE
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-AGRICULTURAL STUDIES
Agriculture (Farming)
INTENSIVE EXTENSIVE
FARMING FARMING
Human Factors
All farming activities need either human labour or machines to do the work. Some farming use very little
labour e.g. sheep farming, others require large labour forces e.g rice farming or tobacco farming.
Availability of labour may influence the type of farming. The farm wages, the skills and family labour
affect farming.
Demand/Market.
This is the customer who buys farm products. Farmers need to sell their crops and animals to make a profit.
The higher the demand the higher the price of the product: and the lower the demand, the lower the price.
The price of the produce and availability of the market are important factors that affect farming.
Finance /Capital.
This is money for the payment of wages, purchase of farm inputs/ or imports. This can affect the type and
state of farming. Some crops are capital intensive e.g. money to set up irrigation facilities etc. Money can
be in the form of loans from banks or grants from the government or capital saved by the farmer.
Government (Political)
Government provide subsidies and loans or inputs to encourage new farming practices but they also place
limits on production to prevent food surpluses. Government influence farming through its police or through
infrastructural development and support services e.g. providing tillage facilities through DDF.
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Transport
This is needed for the transportation of inputs to the farm and outputs to the market. In Zimbabwe and
Zambia commercial farming is concentrated along main roads. Colonial government made efforts to
provide the white commercial farmers with efficient transport services e.g. compare Burma Valley and
Bocha, Buhera e.t.c. Transport network e.g. roads and the type of transport affect farming activities.
Technology
Irrigation and machinery are two examples of expensive technology which increase yields. Genetic
engineering allow new plants to be grown, this reduces diseases and droughts and give higher yields.
Computer control in green houses provides suitable conditions for good quality crops. Type and availability
of equipment and service affect farming activities.
Physical factors
Climate
A minimum temperature of 6oC.
Different crops need a different growing season e.g. wheat 90 days. Rainfall-all crops and animals need
water.
Too much rainfall can pose problem to farmers the same is true with very little rainfall below.
Relief
Temperature decreases by 17oC every 160 metres vertical heights.
Uploads are more exposed to wind and rain.
Sleep slopes also cause thin soils and limit the use of machinery.
Lowland areas are more easily farmed.
Soils
Crops grow best on deep, fertile, free draining soils. Soil type and fertility influences the types of crops that
can be grown, the yields per unit area and the cost of production.
Aspect
The direction a slope faces. In the extreme northern hemisphere south-facing slopes are best for growing
crops and in the southern hemisphere north facing slopes are best for crop production. (Why?)
Pest and diseases
These affect workers; crops and animals. Farmers have to fight them in order to avoid disastrous effects.
Pests which affect crops include locusts, Birds, boring insects, worms.
The farm as a system
Farming can be viewed as a system involving inputs, processes and outputs as elements of the system.
Inputs are the initial things needed to carry out something eg land knowledge, capital. Processes is the work
done, manipulating the inputs in order to produce items. Outputs are the end products from the work
/processes done.
The table below shows the main components of a farming system
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INPUTS PROCESSES OUTPUTS
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Distance to the fields become to long for daily walking.
Availability of space due to low population pressure in area where it is practiced.
The rudimentary type of housing used makes it easier to build new houses than to repair the old ones.
Bush fallowing
This is another type of subsistence agriculture which involves the rotation of cultivated land without
necessarily changing the homes.
The land is left fallow for about 5 years the advantages and disadvantages are more or less the same as
those of shifting cultivation.
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Nomadic pastoralism
This refers to the traditional herding of livestock such as cattle, goats, sheep and donkeys following
pastures without maintaining a permanent home. It is practiced by people known as Nomads in areas
of low rainfall such as the arid and semi-arid regions of Africa such as West Africa. In Africa pastoral
nomadism is practiced by the Masai of East Africa and the Fulani of West Africa.
In recent years this type of farming is generally fading out because of the following reasons.
a) Governments have encouraged permanent settlements to make it easy for the provision of services and
the development of infrastructure.
b) In West Africa the Fulani have been sedentarised and organised into cooperatives with a central well
and About 20 homesteads around the well.
c) Each homestead if allowed about 15 herds of cattle.
d) Permanent homes are built and each farmer is given a plot to cultivate crops.
e) In counties such as Kenya nomads have been commercialised here the quality of the cattle is improved
and the government provides services such as dipping and vaccines.
f) This measure can only succeed if the nomads are educated and trained and this is being done in Kenya.
g) In already damaged areas rehabilitation programmes such as reforestation, regressing and building of
dams is being done and encouraged.
Case study
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Sahel includes countries Mali, Niger, Sudan and Burkina Faso.
The region is hot, dry with short wet conditions and subjected to dust storms from the north.
Vegetation is semi – arid scrub with thorn bushes and baobab.
Pastures bloom from May to August due to short rainy season.
Water holes appear also during the rainy season.
Movements of Fulani
During summer, ITCZ moves northwards bringing rains and the Fulani moves north ahead of the tsetse
flies.
The nomads also move into highlands which are cooler and tsetse fly free.
Settle where there is plenty pastures and water.
They establish temporary settlements in groups of 20 to 40 families.
Men herd cattle while female do small scale agriculture.
As dry conditions occur due to the shift of ITCZ, nomads move to the south, but behind tsetse belt.
These include physical and socioeconomic problems. The physical problems include:
a) Poor and heavily leached soils caused mainly by over cultivation and the fact that the farmers cannot
afford to by fertilizers to maintain fertility.( make fertilizers available and also resettle people).
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b) Cultivation of marginal land due to rapid population growth which comes with a higher demand for
food.( practice effective family planning programmes to contain the exponential growth of population).
c) Low and unreliable rainfall in most parts of Africa reduces productivity. (harness water through the
construction of dams for irrigation purposes).
d) Pests such as the army worm, locusts, ticks and tsetse flies also reduce productivity. (Use chemicals to
control pests and also practice crop rotation.)
e) Diseases such as foot and mouth and anthrax also reduce animal productivity. (vaccinate the animals
and control their movement avoiding the mixing of cattle with the wild buffalo).
Plantation agriculture
- This is the large scale production of one crop on a large piece of land called an estate for a long period
of time. The crop can be perennial or annual.
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Each estate is self- contained and efficiently run with factories, workers houses schools, clinics and
recreational facilities on the estate.
Production is market oriented, the market being domestic or foreign.
There is production of both food crops and industrial raw materials.
They are usually attached to out growers.
They have monocultural tendencies.
They employ a large number of people raising the standards of their lives in the process (examples to
include hippo valley and triangle estate)
Disadvantages
a) Their monoculture tendencies result in rapid removal of nutrients from the soil resulting in exhaustion
of the soil.
b) Large sums of money are repatriated to the mother country since most are foreign owned.
c) They occupy large tracks of land while the indigenous people are landless.
d) They indulge in local politics and at times may sabotage the economy.
e) Extensive clearing of the land may have negative effects on the environment.
f) In some areas there is exploitation of workers as workers earn very little and also workers live in squalid
conditions.
g) They can sometimes rapidly plunder the land and then leave for other countries leaving the land
exhausted.
Case study 1
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Katiyo Tea Estate
Location
Honde valley in the north eastern part of Mutare, on the bank of the Pungwe River on the eastern border
with Mozambique.
Crop
Climatic characteristics
Rainfall 1740mm per annum falling mainly in November to March
Temperature is high during the rainy season.
During summer humidity is high.
Production of tea
Planting stage
It is grown from seeds or cuttings in nursery beds, seeds takes a longer period before it is ready for
harvesting 2-3 years
Cuttings takes a short period
Growing from cuttings ensures high quality
When ready seedlings are transplanted into prepared fields (when about 15 cm high
Constant weeding, and pruning to allow the bush to grow outwards
Harvesting
Starts after 2-3 years if grown from seeds or 9 months if from cuttings.
Done by both females and males
Hired labour is required during this period
2 leaves and a bud is plucked and loaded into baskets
The baskets are offloaded into a tractor.
Harvesting is done at intervals i.e. after 5-7 days in the dry period.
The tea leaves are transported to the factory for processing.
Tea processing
Withering- tea enters into heated whither and loose weight by 25%.
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Extracting rubbish by machine.
Fermentation- leaf cells are broken oxidation changes the colour from green to brown then blackish.
Drying- tea goes into drying trays .
Extractors remove fibre.
Sorting- black tea is sorted into sizes or grades.
Package- done by machines.
Market .
Local market- wholesalers, shops, etc.
Export.
Most are along the the Eastern Highlands – Nyanga, Tanganda, Rusitu, Katiyo, Chiwira, Transau and
Nyamazura due to high rainfalls, cool temperatures for tree crops and fruits.
Many in S.E Lowveld – Chisumbanje, Middle Sabi, Hippo Valley, Tsvovane, Nandi and Triangle
because of low population density, high temperatures for sugarcane, large rivers for dams for irrigation.
Low in the Central Highveld – Mazowe, Seke, Doreens Pride near Kadoma, due to competing land
uses, large population densities.
Few in the North – Sisi near Mhangura and Mushumbi.
Very few to none in the west and South west – Balu, Kezi, and Jotsholo because of too hot and dry,
diseases, poor soils, areas used for ranching and National parks.
Irrigation farming
This refers to the artificial application of water to crops in order to grow crops when the prevailing climatic
and weather conditions cannot sustain crop growth.
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Reasons for practising irrigation agriculture - (these are advantages)
Increase food production.
Produce crops throughout the year.
Deal with the problem of moisture stress.
Bring marginal land into effective use.
Generate more employment.
Produce more industrial raw materials.
Raise the standards of living of the employed.
Improve the national economy.
Harness and utilise water that might have been lost through run off.
Problems
Salinisation of the soil.
Irrigation water contains toxic chemicals derived from fertilizers and pesticides which can contaminate
drinking water sources.
Dams constructed for irrigation water can increase incidences of bilharzia.
Rapid siltation of dams.
It is expensive to set up.
Methods of Irrigation
Question 1. Describe and explain the distribution of irrigation schemes in Zimbabwe shown. Dynamics of
O`level Geography page 131 [ 8 ].
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Case Studies
Case Study 1
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The Sennar dam is situated on the Blue Nile some 260 km southwest of Khartoum was completed in
1925 to supply the Gezira irrigation scheme.
The Jebel Aulia dam is situated upstream of Sennar dam, was constructed and completed in 1966 to
provide storage for irrigation in the low water season (reservoir) and for hydropower generation.
The irrigation system comprises of canals and flood irrigation.
The Managuil main canal was constructed in parallel to the old Gezira main canal to serve the Managuil
extension.
The uniform slope of the land has permitted a very regular layout of fields.
The soils are fairly uniform, and classified as vertisols that have clay content (rich volcanic soils).
Movement of water in the soil is very slow. Where soils crack to good depth, water penetrates to be
followed by roots.
The climate of the area is semi-arid and continental characterised by a low rainfalls
The area has low population densities due to harsh conditions.
Roads have been built to link the scheme to markets. Industries e.g. ginneries have been developed to
process agric products.
Management
The Gezira Management Board, a large centrally managed corporation, is responsible for the
agricultural management of the scheme, lease land to tenants, determines crop rotations and prepares
the land for cotton. For cotton, the Board is responsible for application of fertilizer and pesticides, seed
propagation and distribution and ginning. It is also responsible for the maintenance of the infrastructure,
which includes a railway network of 1,050 km in length, used for transporting cotton.
The Ministry of Irrigation is confined to ensuring the delivery of water into the minor heads as indented
by the block inspectors provided that the water demands are within the canal carrying capacities.
Farmers do not own their lands; they are tenants.
Tenants supply or hire labour, tend the crops, pick seed cotton and transport it to ginnery collection
centres. They are responsible for land preparation for crops other than cotton.
Tenant participation in agriculture has fallen hence rely on family labour, hired resident labour and
migrant labour.
Case Study 2
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Ownership is varied i.e. Sikato, Nandi, Chisumbanje and Middle Sabi are owned by ARDA and Hippo
Valley is owned by Anglo-American company.
The climate of the area is semi-arid and continental characterised by a low rainfalls
It relies on water drawn from dams built on large rivers in the south e.g. Manjirenji and Bangala.
It includes commercial and indigenous out growers growing cotton, sugarcane, wheat coffee, fruits and
beef.
The area has low population densities due to harsh conditions.
The uniform slope of the land has permitted a very regular layout of fields.
The soils are fairly uniform, and classified as vertisols that have clay content (rich volcanic soils).
Roads have been built to link the scheme to markets.
Industries e.g. ginneries have been developed to process agric products e.g. sugar mills.
S.E Lowveld relies on sprinkler and flood irrigation.
Characteristics
Several products are produced in different seasons.
Livestock production complements crop production, with animals feeding on crop residues while their
dung contributes towards increasing humus and fertility of the soil. It is highly mechanised with tractors
combine harvesters, boom sprayers and silage cutters.
Skilled man power and management results in high outputs per unit area.
It is capital intensive and the money is used to buy machinery, vaccines , fertilisers, seeds, extra feeds
for livestock, herbicides and to pay workers.
The money is also used to construct buildings sheds and storage facilities.
Mixed farms practice crop rotation
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Advantages
a) Diversified production ensures that the farmer gets a steady income all year round. This include food
crops, industrial crops, and beverages, poultry, piggery, aquaculture plus a herd of cattle for beef and
for dairy products. It ensures that a farmer is not affected by fluctuations of prices on the market since
the farmer produces several products.
b) High outputs due to the complementary nature of raising animals and food crops.
c) There is maintenance of the ecosystem to some extent due to the rearing of animals and the cultivation
of crops on the same farm.
Commercial ranching
- This refers to the rearing of cattle on a large scale with the sole aim of selling them for a profit.
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Characteristics
The farm covers large areas which are divided into paddocks.
Rotational grazing is practiced.
Large amounts of capital are needed to purchase the land, fence, drilling of boreholes, irrigating fodder
crops, paying workers and veterinary services for the animals, purchase concentrate for fattening.
Owned and operated by +rich individuals or by Parastatals .e.g. CSC. Lemco and Union carbide Mat
south.
There is extensive use of land characterised by low input per unit area of land.
Artificial insemination can be practised to produce breeds with desirable characteristics.
No computers used.
Animal left to roam around looking for pastures.
Less capital required once initial capital has been used.
Ranches scientifically managed.
Animals are vaccinated and dipped regularly.
Diseased animals are slaughtered or treated; quarantining is also done followed by treatment.
Cross breeding is done to suit conditions
Advantages
a) Earns the country valuable foreign currency as there is high demand for our beef in the EU.
b) It makes meat products available for local and foreign markets.
c) It leads to the sprouting of by-product industries such as glue manufacturing companies and shoe
making such as Bata.
d) Makes use of semi- arid land which is otherwise not suitable for agriculture.
e) Rotational grazing is sustainable.
f) Allows for integration with game ranching especially in the drier parts of the country e. g. in Mwenezi.
Problems
a) Frequent droughts- drill bore holes and construct dams. pen feed the animals.
b) Pests and diseases-buy pesticides, dip the animals and avoid mixing the cattle with the buffalo,
quarantine and vaccinate, kill the affected. Cross breed with other breeds which are disease resistance
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Market gardening
Characteristics
Land is under cultivation all year round.
Perishables which require special attention and precise harvesting are grown.
It is capital intensive- for purchasing irrigation equipment, hybrid seedlings, fertilizers agrochemicals,
paying of workers, and construction of green houses, artificial incubators and automatic milkers.
It is labour intensive- picking of flowers and sorting them, nursing seedlings
It employs qualified personnel who in turn ensure proper management and expertise so as to survive
the market completion.
Advantages
a) It produces products in demand on the local market and abroad.
b) It brings in a lot of foreign currency.
c) Provides employment to university graduates.
d) Encourages the growth of fertilizer and pesticides industries.
Disadvantages
a) Can incur huge losses in the event of a natural or human triggered hazard. Crops can be destroyed by
frost, floods, hailstorms and strong winds.
b) Fluctuations of the market can reduce the farmer’s income.
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Irrigation equipment Application of fertilizers and Flowers
Green houses chemicals Cash etc.
Labour Harvesting
Fertilizers and chemicals Transporting
Capital Land preparation
Spraying equipment
Vehicles.
Infrastructure
7 boreholes.
5 green houses.
Three main irrigation systems- overhead, micro jet and T-tap drip system.
The boreholes pump large quantities of water needed at the farm e. g. Over 21000 litres per hour.
The micro jet system is used in green houses.
- It is an intensive type of livestock farming for the purpose of producing milk and related products.
The system is capital intensive.
It requires animal sheds and storage facilities for winter fodder.
Common breeds are jersey brown to yellowish suited to hot humid conditions ( produces milk with a
high butter fat content).
Friesland – large animal with a large udder back and white in colour, can tolerate hot dry regions, it is
economical (preferred by most farmers as it has a high milk production) and also supplies meat
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Guernsey- golden yellow to red with white marks second to jersey in milk fat.
Requires temperate climates.
Milk is processed into cream, butter, cheese, condensed milk and powdered milk.
Can be practiced on small areas.
Requires veterinary services, automatic milkers vaccination, feeding towers, milking.
High output per unit area.
In less economically developed countries transport plays a major role in the distribution of dairy farms.
Dairy farms decrease with distance from the urban where there are good road networks the farms can
be some distance from the market.
Question 1. Describe and explain the distribution of dairy farms in Zimbabwe and Africa. [16], Dynamics
of O`Level Geography page 135.
Case Study
Dairy Farming: The Kintrye Estate.
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This is farming system whereby cows are kept for milk production as at Kintyre dairy farm near both Harare
and Norton along the Harare- Bulawayo road. Or Gushungo Dairy Farm in Mazowe area.
Urban Agriculture
Research work
Agriculture in Zimbabwe
Zimbabwe is a landlocked country in the Southern Africa region with an area of over 390 000 km2. It
is situated between 15 and 22° south latitude and 26 and 34° east longitude.
Climatic conditions are largely sub-tropical with one rainy season, between November and March.
Rainfall reliability decreases from north to south and also from east to west. Only 37% of the country
receives rainfall considered adequate for agriculture.
Zimbabwe was once the bread basket of southern Africa producing most of the food crops but it has
since changed due to a number of factors.
Zimbabwe can be divided into 6 agro ecological regions looking at annual rainfall and annual
temperature variations.
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Natural Region I: Specialised and diversified farming region
This region lies in the east of the country.
It is characterised by high rainfalls of over 1000mm per year, low temperatures, high altitude and steep
slopes.
The country's timber production is located in this region. The plantations are owned mainly by the State
through the Forestry Commission and by multinationals. There are several small owner-operated
plantations and sawmills.
It is ideally suitable for intensive diversified agriculture and livestock production, mainly dairy farming.
Common crops are tropical crops such as coffee and tea, deciduous fruits, such as bananas and apples,
and horticultural crops, such as potatoes, peas and other vegetables. Flowers, such as protease
(Proteaceae spp.), are grown for export.
This region experiences fairly low total rainfall (450-650mm) and is subject to periodic seasonal
droughts and severe dry spells during the rainy season.
The rainfall is too low and uncertain for cash cropping except in certain very favourable localities.
Smallholder farmers grow drought-tolerant varieties of maize, sorghum, pearl millet (mhunga) and
finger millet (rapoko).
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NR IV is ideally suitable for cattle production under extensive production systems and for wildlife
production, but it can be intensified to some extent by the growing of drought-tolerant fodder crops.
Communal farmers occupy 50% of the area of Natural Region IV.
The rainfall in this region is too low and erratic for the reliable production of even drought-resistant
fodder and grain crops like millet and rapoko and farming has to be based on the utilisation of veld
alone.
The extensive form of cattle ranching or game ranching is the only sound farming system for this region.
Included in this region are areas of below 900m altitude, where the mean rainfall is below 450mm in
the Zambezi valley and below 600mm in the Save-Limpopo valleys. 46% of the area of Natural Region
V.
Region V1
This is a more recent demarcation which does not appear on the map. The area around the Tuli circle.
Consists of barren soils unsuitable for arable farming. Used mainly for wild life.
NOTE:
A rainy pentad is defined as the centre one of three five-day periods (pentads) which together receive more
than 40 mm and two of which receive at least 8 mm of rainfall.
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l) Lack of machinery.
m) Political interference.
n) Frequent droughts
o) Pests and diseases.
p) Shortage of labour due to rapid rural to urban migration by the economically active.
Computers – these can be used in irrigation to detect when plants need water and the water is supplied
automatically.
Use of computerised machines in the milking of dairy cows.
Use of computers for the incubation of eggs, this serves time and labour.
Storage of agricultural data base on computers which can quickly be retrieved and used when needed.
Office automation improves communication with farmers in the same line of production. E. g telephone,
fax.
Easy and fast transactions with consumers and suppliers.
Status of orders and consumers kept on real time.
Management information systems, help generate information to assist farmers in decision making.
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Aims of the land reform programme
Rectify the colonial land take over.
Utilise land lying idle and increase food production in the process.
Equitably redistribute the land to the majority blacks.
Relieve pressure on overcrowded communal lands.
Give land to the landless.
Improve the living standards of the poor.
Give land to people displaced during the war of liberation.
Create jobs on farms owned by individuals and co-operatives.
Provide a token of appreciation to those who fought during the liberation struggle.
To facilitate profitable farming by the peasants.
Phase I : 1980s
It began soon after independence in 1980 through an act of parliament which was drawn in the spirit of
the Lancaster house agreement i.e. willing seller, willing buyer. This could not be changed for 10 years.
The government only acquired 40 % of the required 8 million hectares of land to resettle about 162000
families.
The government only managed to resettle 71 000 families in 1992.
Another act of parliament was enacted to remove the willing seller willing buyer close and to limit the
size of the farm and to introduce a land tax which was never implemented.
The aim was to speed up the land reform programme.
The act empowered govt to compulsorily buy the land for redistribution however land owners could
challenge the decision by government in court.
In the 1990s 2.47 million acres were acquired and this benefited only less than 20 000 families.
The land acquired during this phase was of poor quality according to the Human Rights Watch.
In 1997 the government conducted a land identification exercise where it published a list of 1471 farms
it intended to acquire compulsorily.
The costs were to be paid by the British government.
The then secretary of state for the labour government rejected the responsibility of paying for the land
if it were acquired.
In 1998 the Zimbabwe government published a policy frame work on land reform and resettlement
programme phase 2
Phase 2 : LRRP II
The policy frame work envisaged the compulsory purchase of over 50 000 square kilometres from the
112 000 owned by white commercial farmers, public corporations, churches, MNCs in the next 5 years
between 1998-2003.
Broken down it meant that the government was going to compulsorily buy 10 000 square kilometres of
land each year.
In 1998 September the government of Zimbabwe held a donor conference on Harare on the LRRPII to
inform the donor community and involve them in the exercise.
48 countries attended and endorsed unanimously the programme in 1999.
The commercial farmers union offered 15 000 square kilometres of land for sale.
The constitution was amended so that acquisition of land was to be done compulsorily without
compensation.
The draft constitution was put to a referendum where it was rejected.
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A few days later war veterans decided to march on white owned farms biting drums singing and
dancing. As marching continued they began seizing the land violently and when the violence ended
they had seized 110 000 square kilometres of land.
In 2004, the minister for lands, land reform and resettlement John Nkomo declared that all land would
soon become state land.
Farm land deeds would be replaced by 99 year leases and wild life conservancies would be limited to
25 years.
Farmers resettled under A1 and A2 Models 2006.
Newly resettled farmers fail to secure loans because of lack of collateral.
Minister of agriculture was considering legislation which would compel commercial banks to issue
loans to the newly resettled farmers. Failure oif which the operating licence would be withdrawn.
The land reform in Zimbabwe was a strong tool for the 2000, 2008 and 2013 presidential elections
which saw Zanu PF winning resoundingly according to the reports published by the ZANU PF
spokesperson.
Changes in agriculture
Organic farming
Many of today's farm systems are a direct consequence of farming practices originating hundreds of years
ago. There have been numerous changes in other areas. One significant change in recent years has been the
movement to organic farming.
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This does seem to be the case for many practices. For example, there has been a return to crop rotation
and fallow periods and manure and crop residues are being used instead of chemical fertilisers. A greater
diversity of crops is grown - often in the same field so that if a pest does strike it will not affect the
whole crop.
All of this has clear benefits for the environment and is an example of increased sustainability in
agriculture.
There are however some concerns. Converting a farm to be officially organic is a lengthy and very
expensive process. It can take five years for a farm to be recognised as organic.
In the meantime the farmer is paying extra costs for a lower yield with no extra revenue.
Loss of natural habitat - farming can lead to the loss of natural habitats.
The soil itself is an ecosystem and inappropriate farming techniques can lead to soil erosion.
Overgrazing, over cultivation and deforestation all damage the soil making it more prone to the effect
of erosion.
Use of chemicals have potentially damaging effects on the environment. Causing soil pollution and
eutrophication.
INDUSTRIAL STUDIES
Industry
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Industry-any form of economic activity through which people produce goods and services for their
consumption.
Industrialisation-process through which a country establishes manufacturing industries.
A country is referred to as industrialised when production of manufactured goods is the main economic
activity in that country. Less industrialised countries mainly produce agricultural raw materials.
Heavy Industries
- Manufacture heavy and bulky products.
- Use heavy raw materials.
- Involve heavy investment in their production.
- Production is in large scale e.g. ship building, car manufacturing and assembling, oil refineries, steel
rolling mills, fertilizer making plants, glass industries e.g. ZIMASCO, Lancashire in Gweru, ZIMCAST
and ZIMALLOYS in Gweru etc.
Light Industries
- Ones involved in making goods with little volume and weight e.g. textile, cosmetics, plastic, printing,
electronics, cigarette, e.g Phillips, David Whitehead, etc.
Industry as a System
Industry nearly always involves the making or creation of something, hence often looked at as a system.
The three main parts of the system are:
Inputs: The things that are needed to make or create a product. These maybe physical or human e.g.
labour (workers), money or raw materials.
Processes: The events or activities that take place to make a product e.g. watering crops or assembling
a car.
Outputs: The finished product that is sold to a consumer e.g. milk, a television or a car.
Location of Industry
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Market: For any industry to survive, they need customers. Therefore it is very important to locate near
their potential market.
Supply Network: Most industries have a large supply network. To ensure the smooth production of
products it helps being close to suppliers.
Good Housing: To attract any workers it is important to have suitable housing nearby. For quaternary
industries this might be good quality housing for secondary industries this might be high density cheaper
housing.
Good Schools and Hospitals: Again to attract workers and especially their families, it is important to
have good nearby schools and hospitals.
Transport Links: It is important to be close to good roads and rail links so that industries can receive
supplies and distribute products.
Good Communications: It is now very important for industries to have good communications so that
they can contact suppliers and customers.
Reliable Electricity and Water Supply: For all industries a constant electricity supply is essential
because industries can't afford breaks in production.
Available Land: If industries are successful they will want to expand, so most industries will look for
sites that have the potential to expand factories/offices.
Available Raw Materials: For any industries that use raw materials (especially weight loss industries),
it is very important to be close to them.
Water Supply: For many industries, especially manufacturing, it is very important to be near a reliable
water supply (river or reservoir).
Climate: For some industries a good climate can be very important. For example you would not locate
a solar panel research and development company in a place where the sun never shines.
Industrial Inertia – Tendency of an industry to remain in a particular place even when the factors for its
location no longer exist e.g. industries in the Ruhr Region of Germany have remained at the same place
despite closure of coal fields and decline in coal as an energy source.
Hi-tech industry: Industries that are focused on research and development and the production of products
that often contain microchips.
Conglomeration: The process of clustering together in one area.
Types of Industrial Locations
Raw materials based/material oriented industries
These are located on the source of the raw materials.
Such raw materials are bulky and costly to transport.
Some of the raw materials could be perishable and lose most of their weight during the manufacturing
process.
The least cost location of such industries is near the source of raw materials.
Market oriented industries
These are located close to the market.
Such industries produce perishable goods e.g. bakeries and therefore it is cheaper to transport the raw
material over long distances.
Costs of transporting finished goods are reduced because the industry is near the market.
A break of bulk-paint industries
These are industries located on the port and most raw materials are imported
Good examples are oil refining and iron or processing
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Raw materials are bulky thus giving coastal locations more advantage than interior location.
Labour based industries
These are near the source of labour especially if the industries require a lot of skilled labour.
Power/fuel based industries
These are located close to power or fuel supplies.
Most industries in the UK and the USA were located near coal fields because it was the only source of
power.( NB*No longer common***)
Footloose industries
This refers to industries that can be located anywhere without the effect from factors such as resources or
transport. An industry not tied to any particular location, it is not tied to a fixed location. The cost of
transporting both raw materials and finished products is not important for the location of the
industry/firm.
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Importance of ZISCO
Employment creation.
Foreign currency earnings.
Improvement in transport.
Raising living standards of people.
Growth of social services.
Urban growth.
Problems faced by ZISCO
Old machinery and the blast furnace need to be repaired.
Shortage of money.
Poor management.
Too small markets for iron and steel.
Competition from Chinese companies producing iron and steel from scrap metals.
Problems Caused by Industries
Pollution of air, water, land and noise
Exploitation of labourers
Encroaching on to agricultural land.
Repatriation of profits
Corruption/mismanagement
Solutions
Locating away from residential areas.
Educating people on problems caused by pollution.
Introduction of carbon tax.
Impose strict laws against pollution.
Introduction of labour unions.
Percentage share to government for products sold outside the country.
Putting tariffs against imports.
Case Study 2
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Japan is a country to the east of Asiatic continent made of numerous major/large and minor/small
islands.
Lacks basic raw materials and energy at home hence relies on exports.
Examples of automobile companies include the Mitsubishi and Toyota Motor Corporations.
Industrial relocation
Is a situation where an industry shifts from its original site to locate to a new area or different site.
UK Iron and steel industry has relocated from inland, coal and iron ore based location to South Wales
and N.E England.
Causes of relocation
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Government policy.
Environmental pollution.
Raw materials exhaustion.
Changes of market demands and transport.
Effects of relocation
Unemployment.
Increase in crime and prostitution.
Economic declines as shops close down.
Metallurgical industries – 1. Iron and steel at ZISCO in Kwekwe, 2. Basic metals at ZIM ALLOYS,
ZIMCAST in Gweru, ZIMASCO, SALWIRE in Harare and Bulawayo.
Mechanical engineering – Harare, Mutare, Kwekwe, Gweru, and Masvingo, Car industries in Harare at
Willowvale and Mutare, electrical goods in Harare and Bulawayo.
Light industries – textiles in Harare, Bulawayo, Gweru, Kadoma e.g. Martin Spur, David Whitehead in
Chegutu, food stuffs in major towns, foot wear in Gweru e.g. Bata and Bulawayo.
Chemical industries – chemicals in Harare, Bulawayo, Triangle, Sable in Kwekwe, fertilisers in Harare,
Bulawayo and Kwekwe.
Other industries – Hi – Tech industries in Harare and Bulawayo e.g. Phillips, paper and printing in
Harare, Mutare, marondera and Gweru, furniture in Bulawayo and Mutare,
Cotton ginneries near source of raw materials in Kadoma, Chegutu, Muazabani and Sanyati.
The factors that can account for the distribution has been sited earlier on the factors affecting industrial
location.
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Transnational Companies
Are companies with economic operations in more than one country.
Examples of TNCs in Zimbabwe are Anglo – American - UK, Lonrho - UK, Rio Tinto Zinc –
UK, Nestle - Switzerland, Heinz - Germany etc.
Advantages of TNCs locating in a country
Creates jobs for local people
Locals with jobs then spend money in their local economy at local businesses and therefore there is a
positive multiplier effect as extra money gets added to the local economy.
TNCs will pay local and government taxes.
Improves workers skill and education levels
They introduce new technology into the country
Development of Infrastructure like roads.
Diversifies the economy, might move away from the reliance on one industry like farming or tourism
Disadvantages of TNCs locating in a country
Many of the best paid managerial jobs go to foreigners
Local workers often do manual jobs which are poorly paid and often workers suffer exploitation (long
shifts, no breaks, etc.)
There will be some economic leakage as profits from TNCs go back to their home country
Products produced by TNCs maybe too expensive for locals to buy. TNCs may also use local raw
materials.
The increased demand created by TNCs may cause local inflation.
TNC decision makers are often foreign so policies of TNCs may not always benefit local people.
- Formal Economy: The economy that is formally registered with authorities and regulated by the
government. The formal sector will be liable to pay taxes.
- Informal Economy: The section of the economy that is not registered with the government, is not
regulated and does not pay taxes. The informal economy is sometimes called the black market.
Informal Economy
Advantages
Many independent poor people work in the informal sector e.g. car washers or shoe shiners. This often
means the money goes where it is most needed.
It often employs people with low skill and education levels who might normally find it hard to get a
job.
Workers may learn skills which means that they can get jobs in the formal economy.
Many businesses actually work in local communities and recycle waste material (a form of recycling).
Disadvantages
Parts of the informal economy is involved in illegal activities like the drugs and sex industry.
The government does not receive taxes from these businesses.
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Because they are not regulated they don't follow any environmental guidelines and can often cause
pollution.
Workers can be exploited by not being paid fully, not receiving sick pay or being forced to work in
dangerous conditions.
Formal Economy
Advantages
They pay taxes to the government so are contributing to government revenue.
Workers are protected so that they get a proper and regular wage and have safety regulations, etc.
It provides products for the export market which then gain foreign income for the country.
Disadvantages
Many businesses in the formal economy tend to mechanise to try and reduce costs and therefore don't
employ as many people.
The formal sector is often dominated by TNCs and there is often economic leakage out of profits.
Service Industries
- Is an industry which provides back – up to other services such as primary and secondary industries as
well as to people for them to function well.
Tourism as a Service Industry
Tourism: The business or industry of providing information, accommodations, transportation, and other
services to tourists.
Leisure: Any freely chosen activity that takes place in non-work time.
Domestic Tourist: Someone who goes on holiday in the country that they are resident in (live in).
International Tourist: Someone who goes on holiday to a country they are not resident in e.g. they live in
Zimbabwe but go to the USA for holiday.
Resort: A type of large hotel that offers extra facilities like swimming pools, spas, restaurants, bars,
activities, etc.
Package Holiday: This is when all aspects of a holiday e.g. flights, hotel, transfers, etc. are included in one
overall price.
All-inclusive: A hotel or resort that includes everything e.g. food, activities and drink in one overall price.
Growth of Tourism
Tourism is a rapidly growing industry and is considered by many countries to be an important development
strategy. Currently the majority of international tourists go to MEDCs, but many LEDCs are also seeing
rapid growth in tourism.
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Paid Holiday: Not only do an increasing amount of workers receive holiday, they are also paid for it.
This means that people do not lose their weekly income by going on holiday.UK workers get least paid
leave.
Income: More and more people are working in the secondary and tertiary sectors, where pay is generally
higher. Also many more females are now working. This means that more people now have money to
spend on holidays (higher disposable income).
Transport: Air travel has become relatively cheaper and there are now more airports open for holiday
flights.
Advertising: People are now bombarded by holiday adverts on the internet, television, radio, mobile
phones, billboards, etc. This makes people more aware of holiday destinations and possibly more
tempted to book them.
Tourist facilities: Tourist facilities have generally improved and increased in number. There are now
many more hotels of all sizes and most have fairly standard services.
Freedom: More people, especially women and the elderly are free to travel and go on holidays. In
addition formerly closed countries like China now allow most of their citizens to travel.
Passport Ownership and Visa Regulations: More people now own passports so are able to travel and
the process of obtaining visas is now much more straightforward.
A region may experience a decline because of:
Terrorism e.g. Bali bombing or Mumbai terror attacks.
Crime e.g. South Africa.
Natural disasters e.g. tsunami in Indian Ocean or hurricanes in the Caribbean.
Economic downturn e.g. recessions and debt crisis in Zimbabwe from 2000 to 2008.
Wars e.g. Afghanistan.
Tourist Attractions in Zimbabwe
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Physical Attractions
a. Victoria Falls – the waterfalls, rain ball, rainforest, gorges, crocodile farm, traditional dances,
photography, hotels and golf courses.
b. Matopos – the granite topography, caves, monuments, paintings, birds wildlife and vegetation.
c. Nyanga, Vumba – mountains, forests, gardens, gorges, waterfalls, cool climate.
d. Chinhoyi – Limestone caves and paintings.
e. Hwange – wildlife, lodges and vegetation.
f. Gonarezhou – wildlife and scenery.
g. Lake Kariba - fishing, boat cruising, gorge and bird viewing.
h. Matusadona – Vegetation.
i. Mana Pools – wildlife.
j. Dande, Devule–wildlife, hunting and scenery.
k. Kyle, Great Zimbabwe – fishing, wildlife, Mushandike Rrruins, African Heritage.
l. Harare – botanic garden, heroes acre, City life.
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Main Attractions Inland
(a) Wild life conserved in National Parks and Game Reserves. Wildlife is conserved in their natural habitats.
(b) The Famous wildebeest migration in the Mara.
(c) The sunny warm climate which attracts tourists from temperate countries.
(d) Attractive scenery such as the snow capped Mt. Kenya, the Great Rift Valley and its lakes and hot
springs and geysers and great rivers with waterfall
Diverse culture of inland people e.g. the Maasai way of dressing, dancing, housing.
(f) Historical attractions such as Kariandusi near Gilgil and Orgesailie near Magadi featuring artefacts of
Iron Age.
(g) National museums of Kenya in Nairobi.
Question 1
Compare tourism industry of Zimbabwe and Kenya. [10]
Advantages of Tourism
Social/Cultural
Local people can perform traditional dance and music to tourists therefore protecting their local culture.
Tourists may pay to visit museums protecting local artifacts.
May improve countries reputation and create cross-cultural links.
Encourages education in order to work in tourist sector and should improve linguistic skills
Disadvantages
Tourism can increase certain crimes, like prostitution and theft
People may become more materialistic and homogenised with the arrival of international tourists.
May create racial tensions between tourists and locals
Economic
Jobs are created for local workers in hotels, restaurants, etc.
Workers and companies pay taxes to the government. This money can then be invested.
People learn new skills that can then be transferred to other parts of the economy.
New equipment or technology may be introduced to the country which again can be used in other sectors
of the economy.
Local infrastructure like roads and electricity may be improved.
Attracts foreign investment hence country get foreign currency.
Diversification of the economy
Disadvantages
Many of managerial jobs go to overseas workers. Local workers often get low paid jobs
There is economic leakage (loss of money overseas) because many of the tourist companies are TNCs
and the profit is sent elsewhere
Many jobs are only seasonal so workers are only paid half of the year e.g. the ski season is less than 6
months long.
The increased demand for products and services may cause inflation
Countries or regions may become dependent on just one industry.
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Increased congestion on roads
Environmental
National Parks may be created protecting areas of natural beauty
Animals obtain an economic value if people are willing to pay to see them. Sometimes tourist
developments may cause the destruction of forests, sand dunes, etc.
Noise and light pollution created by tourist developments may also interfere with animals.
Problems facing Tourism in Zimbabwe
1. Illegal hunting of animals which reduces some rare wildlife species which attract tourists which reduces
the number of tourists visiting the country e.g. death of Cecil (Lion). The solution using game rangers
to patrol game parks to hunt for illegal hunters and banning trade in game trophies and inspecting
tourists at departure.
2. Pollution of aquatic systems such as Lake Mutirikwi which has caused the death of fish reducing the
number of tourists since some are specifically attracted to fishing. The solution is regular inspection of
factories to ensure treatment of effluents before they are released to water bodies.
3. Lack of incentives e.g. tariffs levies etc.
4. Funding and operation of National Parks has been reduced.
5. Sudden changes in domestic airline schedules.
6. Political instability, disputed elections and failure to respect property rights.
7. International media giving negative publicity of Zimbabwe by portraying it as an insecure country.
8. Lack of tourism national policy.
9. Air fares from and to many parts of the world is high due to high fuel prices which discourages tourists
from coming to Zimbabwe.
- Sustainable tourism: Tourist activities that are socially, environmentally and economically sustainable.
Eco-tourism
Environmentally friendly tourism or tourism emphasizing environmental conservation where tourists and
local communities are involved in enjoying nature as well as conserving it or.
Aspects/Characteristics of Ecotourism
(a) Tourists are guided along marked trails instead of driving to the areas where there are animals.
(b) Telescopic viewing of animals to avoid disturbing animals.
(c) Use of camping sites rather than big tourist hotels so as not to put pressure on resources which animals
depend on.
(d) Prohibiting off road driving and travelling by foot.
(e) Allowing particular types of vehicles.
(f) Warning people against throwing cigarette remains on dry vegetation.
Ecotourism Activities
Bird watching, safari (animal watching), cycling, beach cleaning
How Ecotourist Resorts Can Be Eco-friendly
Tree planting, Use renewable energy sources e.g. wind and solar, build using only local products, serve
only local food, using locally sourced products, employ only local staff, recycle all waste, treat and
clean all water, educate guests about the importance of protecting the environment promote local culture
Protectionism
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- Protectionism is measure that a government uses to try and protect domestic industry. The three main
ways that a government aims to protect its domestic industry are through; tariffs, quotas and subsidies:
a) Tariffs: A tax placed on foreign imports to make them more expensive and less competitive than
locally produced products.
b) Quotas: A limit placed on the amount of foreign imports. By limited the amount of imports this
again should increase the price of them and make them less competitive.
c) Subsidies: Financial support given to domestic producers to make their products cheaper compared
to foreign imports. This might take the form of a grant or loan (money), or it might be reduced taxes
or a plot of land that is given to them to build on.
POPULATION STUDIES
Population
Total number of people occupying a given area.
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Demography-study of statistical data on human populations or the study of population
Census- This is the door to door counting of people, recording of economic activities, age, sex, education,
information flow (e.g. radio) and occupation.
Enumerators - are people who do the counting of people.
Advantages of a census
- Information is collected from almost every corner of a country.
- Information is reliable and fairly detailed hence reasonable planning can be based on such information
i.e. it helps the government to plan for the future.
- Keeps the government more organised.
- Keeps detail of all the people within the country.
- Shows the government the population status of the country.
Disadvantages of a Census
- Very expensive to conduct.
- People may feel uncomfortable revealing their personal details.
- It is time consuming
- Some areas are not reached or inaccessible and information may not be collected.
- There may be language barriers when asking for information.
- Some people can run away from enumerators due to ignorance and low level of education.
Other Ways of Collecting Population Data Include
Sample surveys.
School registers.
Vital registration of events (office of the registrar general).
Maternity clinics and child welfare services.
Population density-number of persons per unit area= number of people in a given area/total area of the
place=XP/km2.
Population distribution-the way people are spread out on the land. If a country's population is distributed in
a regular pattern then we say it has an even population distribution. However, if there are areas with many
people and then areas with few people, then we would say that it has an uneven population distribution.
Sparse population: When not many people live in an area e.g. Commercial areas in Zimbabwe.
Dense population: When a lot of people live in an area e.g. the communal area of Zimbabwe.
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1n 2012, world population was at 7 billion people.
Causes of Sparse Population
Mountainous area e.g. Himalayas that are hard to build houses and transports links on.
Very hot or very cold area e.g. Sahara desert, Namib desert of Africa, or Antarctica, cold desert of
Alaska and Iceland.
A heavily forested area e.g. the Amazon Rainforest.
Areas that flood a lot e.g. Mekong river delta.
Areas with poor economic development.
Areas that regularly suffer from natural disasters e.g. volcanoes or droughts e.g. Sahel region.
Causes of Dense Population
Coastal areas that are good for fishing, trading etc. Brazil and Nigeria.
A flat area of land that is easy to build on.
Areas that are close to a good supply of water e.g. River Thames in London. Water is important for
fishing, drinking, washing, East Asia there are finger-like extension of dense population that follows
the Ganges and Indus rivers. etc.
Areas with good natural resources e.g. wood and minerals e.g. Zambian copper belt and Rand region in
South Africa and Europe’s population distribution is not closely tied to terrain, but more closely tied to
coal fields.
Areas that are close to good fertile agricultural land e.g. Nile valley in Egypt.
Economic development – Areas with good developed transport links, plenty of available jobs, available
electricity and water supply, good communications e.g. internet and mobile phone network, good
quality schools and hospitals e.g. Harare, Johannesburg and Nairobi.
Population Distribution in Africa
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In 2012, Africa had a total population of 1.32 billion.
Regions of low population concentrations
The northern fringe of West Africa – slave trade encouraged conflicts that led to depopulation of certain
regions in Africa.
The desert and semi-desert region of Botswana, Namibia, Angola, Sahel region, western South Africa
and Zimbabwe due harsh climatic conditions.
Landlocked states of west central Africa between Chad and Angola, most tropical zones in Congo,
Gabon, Zaire due rainforests, swamps, pests and diseases.
Horn of Africa (Somalia, Djibouti, Ethiopia, Eritrea) due to aridity and persistent droughts hence low
population densities.
Middle belt of West Africa and river valleys, parts of Zambia and Zimbabwe e.g. Gwaai, S.E. Lowveld–
diseases and pests such as sleeping sickness and river blindness and malaria.
Commercials areas of Zimbabwe.
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Southern Africa in small nodes- the Rand region (rich in diamond and gold), coastal areas in the east,
in Natal and arrears of (Johannesburg, Pretoria) due to industrial conurbations.
Along railway lines in Zimbabwe and Zambia, N. Eastern Zimbabwe due to economic development,
agriculture and mining e.g. copper belt in Zambia.
Shores of Lake Victoria population density is 100 people/ km2.
Availability of water and pastures also encourage high population concentrations.
Mining towns and urban areas due to better facilities and employment.
Communal areas of Zimbabwe have high population densities.
Zimbabwe has total population of 13,061,239 where 52% are women and 48 are men (ZIMSTAT 2012).
Harare with a population of 2,123,132.
High population densities – over 41 people per km2
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a. A horse shoe shaped area from NE to East and SE of the country, Eastern Mash west, Southern Mash
Central, Manicaland Central, Masvingo and Southern Midlands due to cool, wet, good agric soils,
disease free, industries, transport networks, mining and towns.
Medium population densities – 21 – 40 people per km2
a. High density areas, west of Kadoma, Karoi, around Bulawayo and Plumtree, North of Nyangaand west
of Zishavane due to agro – ecological region and Land Apportionment factors ( 1930), small industrial
towns and commercial centres.
Low population densities – below 0-20 people per km2
a. Low veld areas ( Limpopo valleys), around Hwange, Kariba, Beitbridge, Gweru, Kwekwe etc. this is
due to hot, dry, poor soils e.g. Kalahari sands, national parks and forest lands, diseases, remote,
commercial farms and mining concessions.
When describing a graph it is important look for trends, changes in trends e.g. quicker increase, slower
increase and also anomalies.
It is also very important to support your findings with evidence (this means figures e.g. dates and
population figures).
From 1750 to the present day the world's population has been constantly increasing. In 1750 the
population was less than 1 billion.
The population rose very slowly for the next two hundred years reaching 1.2 billion in 1850 and 2.7
billion in 1950. From 1950 to 2012 the population started to rise at a faster rate. By 1975 it reached
about 4 billion and 2000 about 6 billion.
In the last decade the population has increased at an even faster rate reaching 7 billion by 2012.
Population growth takes place when birth rates are higher than death rates (natural increase).
Population Terms
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Natural increase: When birth rates are higher than death rates.
Natural decrease: Where death rates are higher than birth rates.
Growth Rate - birth Rate – death rate.
Birth rates: The number of births per 1000 of population per year.
Birth Rate = Number of births x 1000
Total population
Dependency Ratio: The ratio between the amount of dependents (old and young) and the economically
active.
Young Dependents: The number or the percentage of the population under the age of 16.
Old Dependents: The number or the percentage of the population over the age of 65.
Economically Active: People between the ages of 16 and 65. This is basically the working active group.
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Causes of High Birth Rate
Demographic means population and transition means change, so the DTM basically means the population
change model. The DTM looks at how a country's population may change as it develops. It looks at birth
rates, death rates and total population. The DTM is usually divided into four stages. Stage 1 is the poorest
stage and stage 4 is the richest stage.
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Stage 1: High fluctuating
High birth rate and high death rate due to inadequate food supply, wars, diseases and insufficient
medical facilities.
Little or no increase in population.
Was experienced in Europe before 19th Century.
Population Pyramids
A population pyramid shows the age and sex structure of the country.
Population pyramids can be related to stages in the DTM.
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Left hand side represents male proportion
It`s broad at the base due to factors contributing to high fertility rates already discussed.
Hollows for ages 5-9 due to high mortality rate.
Thins towards the top due to the low life expectancy (average number of years a person is expected to
live) as few people survive to 70 years.
Tapers towards the top due to relatively high death rates throughout age groups.
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Narrow at the base due to low birth rates causing low population of children and young people.
Broadens towards the top due to high life expectancy leading to a high population of old people (ageing
population).
Broadens towards the top which is an indication of low mortality rate throughout age groups.
Strain on budget due to developing countries having a large population of young people whose health
and education cost is high and developing countries having a large proportion of old people whose cost
of health and social welfare is high.
Low quality of education and health care in developing countries due high population leading to the
high cost of those services.
Better quality of health and education in developing countries due low population.
Strain on working population in developing countries since most of the money is consumed leaving less
for investment. Large population of old people does the same in developing countries.
Boost in food production when there is a large proportion of males due to the availability of a large
labour force.
Heavy taxation of the working population when the dependency of young and old is high in order to
avail funds for provision of social amenities.
Large number of females than males leads to low birth rates and consequently slow growth of
population.
Increase in promiscuity when there are a large number of females than males.
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Ageing Population
This is when the proportion of old dependents is increasing. This happens because life expectancy increases,
but also because birth rates start to fall. This happens in stage 4 of the DTM (it is currently happening in
very developed countries like Japan).
Young Population: When talking about a young population, you are usually referring to young dependents
(those under the age of 16)..
Case Study
Pro-natalist Policy: A policy that encourages couples to have more children. You can not force people to
have more children so you have to offer incentives instead e.g. free childcare or even money.
A government can't force couples to have more children, so instead it must offer incentives. Incentives may
include:
Cash payments.
Free or subsidised healthcare and childcare.
Free or subsidised education.
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Reduced tax rates.
Child benefits e.g. weekly or monthly payments.
Poster and advertising campaigns
Singapore's Pro-natalist Policy
Singapore is a developed country in SE Asia with a population of about 5 million people. For many
years the Singaporean government has believed that Singapore is underpopulated and has tried to
increase its population.
Singapore has one of the lowest total fertility rates in the world, standing at 1.1, which is well below
the replacement rate of 2.1. Already 36% of the Singapore population is made up of foreign nationals
and in some sectors like industry, 80% of the workers are foreign.
To overcome worker shortages, the Singapore government has encouraged immigration, but it is also
trying to increase the population through raising birth rates.
The government is doing this in a number of ways. It has increased maternity leave by 50% to 12 weeks
and it will cover the cost of maternity leave (the cost to the parents’ employers) for the first four babies.
The Singapore government is also increasing child benefits paid to families. The government will pay
money into a special bank account of up to nearly $1000 for six years.
The Singapore government has also sponsored dating organisations to encourage people to get married
earlier and start having children.
Anti-natalist policy: A policy that attempts to reduce birth rates. This might be through better education
and supply of contraception or through much stricter policies like China's one child policy.
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were able to work manual jobs, whereas females would be lost after marriage (females normally went
to live with their husband’s family).
There were a number of exceptions to the rules, if you had twins or triplets this was fine, if your first
child had a physical or mental disability you could have a second, families in rural areas (farming areas)
were often allowed a second, ethnic minorities were allowed a second and often couples who bribed
officials could have a second.
The policy has been relatively successful, birth rates have fallen from a peak off 44 in the 1950's down
to just 12. China's population is also expected to peak in the next 20 years and then slowly start to
decrease. Because of its success there have been further relaxations including:
- All of families in females areas can now have two
- Two people who marry from single children families they are allowed two
- Females are better educated about contraception and are free to make their own choices.
However, there are also a few problems:
China is still overpopulated; there are over 1.3 billion Chinese.
There is a male female imbalance in the population.
People are demanding greater freedom and choice.
China will slowly get an ageing population.
There are large numbers of abandoned children
Consequences of Population Growth
Negative Effects
1. Pressure on land leading to land fragmentation.
2. Environmental degradation when people clear forests to make room for settlement and agriculture.
3. Low investment and slow growth of industry as the government spends a lot of money on education and
medical facilities leaving less for investment.
4. Lowering GDP (aggregate value of goods and services that a country can produce) due to inability to
save any money for investment.
5. High rate of unemployment due to employment sector growing at a slower rate than population growth.
6. Towns face problems of water shortage, pressure on social amenities and high cost of housing leading to
development of informal settlements such as slums which expand covering agricultural land surrounding
the towns.
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Negative Effects
1. High government spending on health and social welfare as the population consists of a high proportion
of old people due to low birth rates and low death rates.
2. High cost of production since there is a small work force consisting of skilled people whose wages are
high.
3. Underutilisation of resources such as agriculture and mineral resources since there is shortage of labour
due to sparse population and most of it being concentrated in urban areas.
4. Inadequate market for goods and services due to a small population.
5. Underdevelopment and low living standards in rural areas since a large percentage of people live in urban
areas.
6. Traffic congestion and atmospheric and noise pollution in urban areas due to continuous expansion of
towns.
7. Reduced food production as towns expand and engulf surrounding agricultural land.
Optimum Population
- When population and resources are perfectly matched. In reality this is almost impossible to achieve.
-
Carrying Capacity: The amount of people that the resources of a country can support. The carrying capacity
of a country can change with improvements in technology e.g. desalination, discoveries of new resources,
or the loss of existing resources e.g. volcanic eruption destroying farm land.
Malthus
Malthus looked at population and resources and believed that population was growing at a much fast
rate than resources.
He believed that this would cause a series of preventative and positive checks.
Preventative checks would be people trying to reduce population growth themselves and positive checks
would be famines and conflicts.
Boserup
Boserup was a more optimistic person who believed that humans always came up with solutions to
problems.
Her famous saying was 'necessity is the mother of invention' which basically means that humans will
also find a solution to resource shortages e.g. desalination, development of renewable energy.
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Symptoms of Cholera
i. Severe diarrhoea (watery faeces) like “rice” water.
ii. Vomiting
iii. Fever (body temperatures over 40℃).
iv. Muscular cramps and weakness.
Treatment
i. To replace the body fluids and salts (rehydration) with a solution of water; salt and sugar (SSS).
ii. Use of antibiotics which kill the bacteria.
iii. Notification since it spreads over quickly.
iv. Personal and food hygiene are important in preventing the spread of the disease.
v. Immunisation if there is outbreak.
The mosquito lays about 200 to 300 eggs on the water surfaces.
They hatch and larvae hangs under the surface of water film.
The larvae has a head thorax and abdomen.
Larvae sheds its outer covering (cuticle) in a process called moulting.
The larvae will develop into a pupa.
The pupa develops into an adult which climbs out onto water surface.
Later its cuticle will harden and then flies as adult mosquito.
Spraying oil on surfaces of stagnant water to kill the larvae (will sink and suffocate due to surface
tension of water).
Using insecticides to destroy stages of the insect.
Drain all stagnant water and get rid of containers that may store water.
Prevention of bites by sleeping covered with a mosquito net, using repellents on skin surfaces and
wearing long sleeves and covering legs.
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Use of preventive drugs such as paludrine, deltraprim and malaquine as prophylatic measure.
Correct dosage and usage of drugs such as chloroquine as treatment measures.
Bilharzia
Symptoms
Transmission
The parasitic larvae live in fresh water and can penetrate human skin, placing people at risk through
everyday activities such as washing, swimming or fetching water.
The larvae migrate to the blood vessels where they mate and produce eggs. Some eggs travel to the
bladder or intestines and are passed into the urine or stool. Others remain trapped in the body and cause
damage to internal organs.
Education campaigns about risks of infection by bathing in fresh water lakes and ponds.
Praziquantel is the primary form of treatment.
A single dose of praziquantel has been shown to reduce the severity of symptoms in cases of subsequent
re-infection.
Access to safe water.
Migration
Temporary Migration: Migration for a limited period, this might only be for a few weeks or even several
years.
Permanent Migration: Migration with the intention of staying forever.
Forced Migration: When people are forced to migrate, often because their life is in danger.
Voluntary Migration: When people freely choose to migrate e.g. for better weather or better universities.
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Economic Migration: Migration for work e.g. better salary or promotion
Seasonal Migration: Migration just for a particular season e.g. the ski season or the harvesting season
Commuting: Movement from home to workplace and vice versa.
Emigrant: A person who leaves a country to migrate to another.
Immigrant: A migrant arriving in a new country.
Migration Balance: The difference between emigrants and immigrants. If a country has more emigrants
than immigrants that it is experiencing net migration loss. If a country has more immigrants than emigrants
then it is experiencing net migration gain.
immigration−emigration X1000
Rate of net migration = Total population
Causes of Migration
Push Factors
-Problems or circumstances which force out a person from his/her area of residence.
1. Pressure on land due to increase in population which cause people to move to other areas where land is
available e.g. from Masvingo Province to Gokwe North.
2. Land becoming too poor to support crops which cause people to move to other areas where fertile land
is available.
3. Unemployment and underemployment which cause people to move to other areas to seek jobs or better
paying ones.
4. Insecurity such as tribal clashes and terror gangs which cause people to other safer places.
5. Persecution of specific religious groups due to their faith which causes them to move to areas where they
can practise their faith freely e.g. Jews from Europe to Israel.
6. Political persecution e.g. many Zimbabweans moved to neighbouring countries ( South Africa) during
2008 political instability.
7. Occurrence of natural calamities such as diseases, floods and severe droughts forcing people out of their
place of residence e.g. in monsoon Asia.
8. Government policy where people are moved from one area to give room for development e.g. Tokwe
Mukosi dam.
Pull Factors
Types of Migration
- Two basic types namely: Internal and External
Internal migration
-Migration within a country e.g. Harare to Kadoma
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Rural to urban Migration
-Movement of people from rural areas to urban areas.
It involves:
1. Youth who have completed various levels of education moving to urban areas to seek employment in
while collar jobs.
2. People moving to urban areas in search of alternative ways of earning a living due to shortage of land in
rural areas, unemployment and low prices for agricultural produce.
3. Traders relocating to urban areas where there is a larger market as the people in rural areas have low
purchasing power.
4. People moving to urban areas where there is adequate social amenities such as hospitals, entertainment,
electricity and generally exciting life.
5. Youth seeking for further education who join universities and colleges many of which are located in
urban areas.
6. Transfer of people employed in rural areas to urban areas.
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Urban to urban -Movement of people from one urban area to another or from one part of urban area to
another e.g. Kadoma to Gweru.
People moving from one part of town to another due to:
- Transfer.
- in search of affordable housing.
- in search of better employment.
- in search of better business opportunity
External Migration
Movement of people from one country to another e.g. Zimbabwe to South Africa or China.
It involves:
People who seek employment abroad for a short period who end up settling permanently.
Refugees who are forced out of their country by factors such as war.
People seeking political asylum due to political persecution in their country.
Government employees such as ambassadors who are in assignment abroad.
Positive Effects
Reduced unemployment.
Reduced pressure on schools and hospitals.
Remittances sent by family and friends living abroad. Remittances go straight into the hands of the
people, not the government.
Improved relations with foreign countries. Migrants may return home with new skills and knowledge
of new technology
Negative Effects
Reduced birth and fertility rate and people in reproductive age range leave.
Often skilled and educated migrants leave 'Brain Drain'.
The dependency ratio increases as the economically active leave.
A dependency on remittances develops.
There may be shortage of workers, especially during harvests
Family separation.
Destination Country (receiving country)
Positive Effects
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Source of manual workers who are prepared to work dirty low paid jobs e.g. farming, construction and
cleaning.
Also source of skilled workers who are added to skilled workforce 'Brain Gain' e.g. teachers, nurses and
lawyers to South Africa in 2008.
New cultures e.g. food and dance.
Improved links with source countries, possible new markets e.g. Zimbabwe and South Africa.
Negative Effects
Possible racial tension. South African will often blame Zimbabweans for taking their jobs.
Inflation caused by increase demand.
Pressure on schools and hospitals.
Possible unemployment
Pressure on housing, electricity, water, etc.
Increased congestion and pollution
On the Individual
Positive Effects
Improved living standard of the worker resulting from savings made from income gained after
employment.
Acquisition of skills and change in attitude due to exposure which may cause some town dwellers to
change their way of life and become more sophisticated.
Negative Effects
Lower fertility rates when some people who have migrated to towns take long time before marrying as
they try to achieve various goals in their lives.
Immorality may arise may arise when urban migrants lose touch with their cultural values.
Marriage breakages may occur when spouses are separated for long periods of time.
Remittances: Money that is sent home to friends and family by migrants living in a different location, often
overseas.
Refugee
A person who has been forced to leave their home and their country. This might be because of a natural
disaster, war, religious or political persecution.
Persecution: When someone is attacked for what they believe in e.g. their religion or political belief.
Internally displaced person (IDP): When someone has been forced to leave their home but not their country.
Asylum Seekers: Someone who is trying to get refuge (residency) in a foreign country because their life is
in danger in their home country. This is usually because of their political or religious beliefs.
Reasons for becoming a refugee
War e.g. Iraq
Natural disaster e.g. Indian Ocean tsunami
Famine and/or drought in the Sahel region.
Political and ethnic persecution e.g. Syria.
Problems faced by refugees
No housing.
Shortage of food and water.
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No job or no money.
Poor medical care.
Disease.
Poor sanitation.
Language barriers
Problems faced by receiving country
No education for children.
Cost of providing food and water.
Cost of providing education for children and medical care for everyone.
Possible spread of disease to native population.
Increased pollution and congestion
Possible racial tension.
Language problems of dealing with refugees
Increased unemployment.
Possible inflation because of rising demand
Solutions to refugee problem
The return of migrants to their home (1st choice).
The return of migrants to areas or countries near their home (2nd choice)
Migrants settled in a foreign country a long way from their home (3rd choice).
SETTLEMENT STUDIES
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Settlement
Settlement: A place where people live. A settlement can range from one an isolated building to a capital
city of over 20 million people).
Site: The actual location or place that a settlement is built.
Situation: The area surrounding the site of a settlement. For example you might talk about if the settlement
is near a river, or near the coast or in a valley surrounded by mountains.
A settlement’s location can also be described in relation with other settlements.
Settlements can also be described in terms of their size, structure and function.
Settlements can grow from being hamlets, to villages, then to towns, to cities or even larger settlements
known as conurbations or megalopolis.
As the village grows in size the range of activities within it increases.
In a town a there is a shift to non-agricultural activities thus distinguishing it from a village.
Urban sprawl-this is when two or more towns grow into each other.
The result of an urban sprawl is called a conurbation.
Urban: The built up area, any city with a population of 10,000 people or more.
Rural: Basically the countryside (everywhere outside urban areas). Rural areas maybe farmland, forest,
desert or savanna depending on where you are in the world. Rural areas do contain small settlements of less
than 10,000 people e.g. hamlets and villages.
MEDC: More economically developed country. Basically a richer country e.g. US, Japan or UK
LEDC: Less economically developed country. Basically a poorer country e.g. Uganda, Bangladesh and
Zimbabwe.
Settlement classification
Rural Settlements
Settlements that are found in the countryside (rural areas) and contain less than 10,000 residents.
Rural settlements are those settlements where mostly primary activities occur.
These include activities like mining, farming, fishing and forestry.
The populations of these settlements often depend on the surrounding land.
As such settlements grow; they also increase the variety of activities and may develop into urban
settlements.
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Urban Settlements
Types of settlements
Accessibility
The need to communicate with other areas for trade and travel purposes is another important factor that
influences settlement patterns.
Settlements are often located along transport routes and communication lines.
These may be roads, railway lines or water routes.
Such settlements are also known as Nodal settlements
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Nodal settlements-these are settlements that converge along roads, railway lines, water routes, mountain
passes, gaps river confluences and valleys.
Nodal settlements are heavily influenced by communication networks.
Availability of resources
Hwange is mostly a coal town.
A lot of settlements are located near natural resources that are necessary for people’s livelihood.
For example water, minerals, wood, fertile soil and grass.
Minerals such as asbestos have acted as a catalyst towards the formation of towns like Zvishavane and
coal in Hwange.
Barriers
Human preferences and the influence of technology
Most barriers that prevented settlements from being built in certain areas have since been overcome.
Settlements are now being built in areas previously marginalized.
For example settlements are now being built even on steep slope using landscaping.
Urban area settlements are always planned although spontaneous settlements, which are usually illegal,
often sprout out for example Epworth and Hopely farm.
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Circular pattern
Is a common pattern on desert nomadic camps, around dwalas, volcanic hills or wells and watering
holes in semi-arid areas.
Some tribes e.g. The Kayapo in the Amazon Basin live in circular villages for cultural reasons.
They live in the outer houses and the central house is a meeting place.
Nucleated/Compact
Settlements in rural areas can be nucleated/gathered around market places, commercial farming areas
or in camps.
Such settlements tend to be arranged in much the same manner as electrons in an atom.
Settlements can also be dispersed especially in areas with fewer resources that cannot support dense
populations.
This is also common pattern in commercial farming, communal areas with ragged terrain and areas with
poor soils.
Haphazard settlement patterns can be dispersed or compact but they usually do not conform to a
recognisable shape showing a lack of planning.
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Settlement Growth (Functions)
Function: The job, purpose or use of a settlement. Large settlements will have more than one function
and these functions may change over time.
Functions may include:
- Shopping (retail), business (commercial), farming (agricultural), housing (residential),
educational, healthcare, administration (local or national government), fishing, tourism,
entertainment, sporting etc.
Rural Areas: Rural areas tend to have a lot less functions than urban areas. The main purpose of
settlements in rural areas is normally agriculture (farming) and possibly tourism. This is because rural
areas have less people, poorer transport, poorer communication, less technology and the land is better
used for other purposes i.e. agriculture.
Urban Areas: Urban areas tend to have a lot more functions ranging from shopping functions, to
educational functions, to transport functions, to administrative functions and residential functions. The
bigger the urban area, the more functions that it normally has.
Settlement Hierarchy and Services
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Hierarchy: Placing things in an order of importance.
The hierarchy of a settlement normally depends on three variables:
The size of population, the range and number of services and the sphere of influence
Obviously these three variables are very much interconnected. For services to be offered there has to
be a minimum threshold population. When services are then offered more people are attracted. As more
people are attracted more services are offered and the sphere of influence increases.
As you move down the settlement hierarchy the number of settlements increase. For example you only
get one capital city (near the top of the hierarchy) in each country, but you get thousands of isolated
buildings (farms - near the bottom of the hierarchy) in every country.
1. Sphere of Influence: The distance or area people travel from to access a service i.e. the area served by
a settlement or service.
2. Services: Facilities that are offered to people e.g. supermarket, cinema, and school or train station.
Services have a threshold population, which helps explain why bigger settlements have more services.
3. Range: This usually refers to the number of different services e.g. a school, a post office, etc. It can also
refer to the distance people travel to access a service or settlement.
4. Threshold Population: The minimum amount of people required for a service to be offered and remain
open.
5. High Order Goods (Comparison): Goods that people buy less frequently. They tend to be more
expensive and people will normally compare quality and price before purchasing e.g. a TV, car or
holiday.
6. Low Order Goods (Convenience): Goods that people buy every day. They don't usually cost much
money and people would not normally travel far to buy them e.g. bread and milk.
Quality of life in rural areas in Zimbabwe
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95% of the rural households used wood as the main source of fuel for cooking.
52% of the rural housing units had no access to a toilet or sanitation facilities.
63% of the rural housing units had access to safe drinking water.
5% of rural housing units in the country had electricity
18% of the country’s rural people lived in modern houses, compared to 90% in urban areas.
82% of the country’s rural population lives in either traditional structures built out of pole and dagga
with grass thatch, bricks with grass thatch or mixed dwellings with one or more modern structures with
corrugated iron sheets, cement roofing or asbestos roofing.
According to the 1992 Census, rural people do not have access to shops, clinics or schools.
This is the shape or form of urban areas in relation to land-use models or urban morphology.
Models are used to describe and explain the structure of cities.
A model is a systematic description of an object in this case a typical city.
There are three urban land use models i.e. the concentric model (1924) by Burgess, the Sector Model
(1939) by Hoyt and the Multi-nuclei Model (1945) by Harris and Ullman.
These models attempt to describe what a typical town/city or urban settlement looks like, how it came
to be what it is (how it developed over the years) and why.
Land use i.e. what the land is used for in urban area differs with each area.
Although land uses are usually mixed for example some industries can be found in residential areas
land uses tend to be defined.
Most areas have one dominant land use.
These can be classified into industrial, commercial and residential.
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The concentric model/Burgess’s model (1924)
It was formulated by Burgess and Park in 1924 after their studies of the city of Chicago in the United
States.
Their study revealed that the city could be divided into a number of concentric land-use zones:
A. The Central Business District
B. The Zone of transition
C. The Zone of workingmen’s houses
D. The Zone of middle income or medium density housing
E. The Commuter Zone
The model assumes that the city grows from a single nucleus (core) in concentric circles of distinct land
uses.
The city grows by urban ecology or expansion due to demand of different goods and services.
The city will continue to grow into surrounding rural areas.
The CBD
It is the nucleus of the city
All (communication) routes meet in this area.
It has high rise buildings/skyscrapers.
Rentals are normally high in this area.
It has very few people and traffic during the night and high traffic densities of people and traffic during
the day.
It is the commercial core where hotels, banks, specialized services, theatres, departmental stores,
finance houses and cinemas are found.
Zone of transition
It surrounds the CBD.
It has residential areas with poor housing.
It has offices and light industries.
It is characterised by industrial functions that require a lot of land.
It is famous for its crimes and social problems for example prostitution.
It is characterised by transient population, migrant workers, the poor, aged and unemployment for
example Mbare and Avenues.
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Is found near heavy industries for example Highfield and Glen Norah suburbs near Willowvale
industries and Mbare and Graniteside Industries.
The density of houses per unit area is high
The zone is characterized by high density suburbs with each house located on a small plot of land.
This area is occupied by factory works, single houses, small yards and untarred roads.
Commuter zone
Is located some distance away from the city centre.
People use commute to the CBD in order to get to work using trains, cars and buses.
The zone starts off with low density, high income residential areas, with large spaced houses and
gardens.
In some places market gardening may be practiced for example Honey Dew farm in Greendale.
They usually have a suburban shopping centre for example Sam Levy in Borrowdale and Kamphinsa
in Greendale.
The zone may also give way to larger farms supplying fresh fruits, dairy products and vegetables to the
town.
Sometimes the farming zone may be interrupted by small dormitory towns such as Chitungwiza.
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In making the model Hoyt made some assumptions
The model assumes wealthy people who can afford the highest rentals and rates chose the best sites.
Wealthy residents can afford private cars or transportation thus they live further from industry and
near main roads.
Similar land uses attract each other and repel other land uses.
This process is referred to as sector development
The city or town as a single CBD or core.
People need to move from one area of the town to another.
The model
According to Hoyt areas alongside main roads/communication lines attract the highest rent and rates.
The city grows in a series of wedges.
Land use follows transport routes from the CBD.
Once a certain area has developed a distinctive land use or function it tends to retain that land use as
the city grows outwards
Hoyt also identifies different residential zones in relation to income, opportunity and class.
Sectors thus replace the rings in Burgess and Park’s model.
This is because of unequal access as the city grows outwards along major routes.
Major routes attract manufacturing.
Next to the industrial zone are low class worker’s houses for example Mbare and Leighton industries,
Willowvale and Highfields and Mbare and Graniteside.
These houses are followed by middle class houses (Waterfalls next to Mbare) and then high income
houses.
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They made their study well after the other two models had been published and thus had the benefit of
hindsight and cities had since grown in size.
They realised the fact that modern cities have a more complex structure than described by the
Concentric and Sector models
Cities usually grow from several independent nuclei rather than or in addition to the main CBD.
These cores include sub-urban shopping centres in most modern cities.
Each of these nucleus acts as a point of growth and usually has some of the functions found in the main
CBD and other nuclei for example it might have banks, shopping malls, supermarkets etc.
For example Sam Levy shopping centre, Kamphinsa, Westgate, Makoni shopping centres
These centres grow with time to merge with each other to form one large urban centre.
Harris and Ullman were able to study later urban settlements that had satellite residential and industrial
suburbs in their model.
If the main city becomes too large and congested some functions may disperse to form new nuclei.
Multiple nuclei thus develop out of the need for quick access to the centre, to keep certain land uses
apart and to decentralise.
The city of Harare closely approximates this model with the main large CBD at the centre and various
nuclei in the form of shopping centres such as Borrowdale, Same Levy, Machipisa in Highfield,
Kamphinsa in Greendale, Westgate, Pendennis in Mt Pleasant etc.
It also has satellite towns in Ruwa and Chitungwiza.
Other cities have satellite towns around them for example Norton, Chitungwiza and Ruwa around
Harare
There are very few large urban settlements in Zimbabwe
Most urban centres rose out of administrative centres for example Harare, Bulawayo, Gweru, Bindura
and Marondera act as provincial administrative centers
Some towns began as mining centres for example Hwange, Zvishavane, Shurugwi, Kwekwe, Bindura,
Kadoma and Gwanda.
Some grew as service centres. For example some towns act as agricultural service centers for
surrounding farmlands e.g. Harare, Gweru, Bulawayo, Mutare ec.
A few towns grew as tourist/resort towns for example Victoria Falls, Kariba and Masvingo.
Harare
According to the 2012 census, Harare has a population of 2 098 199 people, with a male population of:
1 011 831 and a female population of: 1 086 368
It is Zimbabwe’s administrative capital and largest city.
It is the focal point of all roads, rail and air routes in Zimbabwe.
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It was granted municipal status in 1897.
The railway line reached Harare in 1899 from Beira.
It became a city in 1935.
Industries sprouted up including motor assembling, trucks, radios, furniture etc.
Harare is also Zimbabwe’s largest commercial centre.
It is also the country’s financial centre where most of the banks are found.
Bulawayo
Bulawayo resembles the Hoyt`s sector model.
Is the second city in Zimbabwe with a population of 620 936 people, 309607 males and 311 329
females.
Is a nodal town linked by roads, rail being headquarters of NRZ and air routes.
It has an iron grid street pattern with wider roads.
Has a variety of industries including tyre manufacturing and cement manufacturing however some are
not functional due to economic instability prevailing. Most industries are situated to the west.
Residential high density and low income areas are close to the industrial zones and include Mpopoma,
Nkulumane and Emakhandeni.
Low density areas are to south, east and north-east.
It is more based on ranching and mining.
It is also linked by a railway line to South Africa, Botswana and Zambia hence easier for importation
and exportation of goods.
Has good communication links and has been the host for International trade fairs.
Is a tourist centre with several hotels and attractions including Matopo National Park, Khami,
Umzingwane Dam and Chipangali sanctuary.
The town has water problems and many industries have relocated to other towns.
Gweru
Has a population of 124 735 people, 62 760 males and 61 975
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Is the administrative capital of Midlands region, a route centre situated on Harare – Bulawayo road and
railway route.
It is a nodal centre with rail branches to Shurugwi, Masvingo and low veld.
Dabuka near Gweru handle most of the country`s international traffic.
Ii also lies in a rich mining region with Chrome in Shurugwi and iron at Redcliff.
Industries include footwear, engineering, dairy processing and publishing.
It hosts the Airforce of Zimbabwe and Zimbabwe Military Academy.
The CBD forms the commercial zone.
Industrial zone is to the west. Near railway station.
High density residential areas are close to industries to the west and north west.
Low densities are to the south, east and north-east.
Senga being the only one far away from the industrial zone.
Mutare
Has a population of 131 808, 68734 males and 63 074 females.
Is Manicaland`s administrative capital located near the Christmas pass.
It lies in rich agricultural area hence developed in commercial and industrial centre.
It is accessible to the Indian Ocean.
Industries include paper and timber, furniture, tea and coffee processing and a car assembly.
It is a tourist destination with attractions like mountain climbing, wildlife, Vumba, Nyanga and
Chimanimani mountains, Chirinda forests, hot springs.
It has a well-planned CBD, residential suburbs and suburban services as well as communication service.
Urban Housing
Council Housing: This is government housing which is usually given to people that are unemployed and
have a low income. The rent on council houses are lower than the rent on private property.
Detached Housing: A single house that is not attached to any other house. A detached house will normally
have a garden and a drive. These types of houses are normally found in the suburbs.
Semi-Detached Housing: Two houses that are joined together. They will probably have individual gardens
and drives. These types of houses are normally found in the suburbs.
Terraced Housing: A long line of attached houses. These are typical in old industrial cities of the UK.
They are normally found in the transition zone area and they would have been housing for people working
in the factories. They were very basic houses, often with no electricity and an outside toilet. Many have
now been knocked down or improved.
Bungalow: This is a house with only one floor. They are very popular amongst old people who find it hard
to use stairs. Bungalows can be detached or semi-detached. They are normally found in the suburbs.
Flats or Apartments: These are buildings with multiple levels. Normally a flat or apartment will only be on
one floor within the block of flats or the apartment building.
Urban Problems
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Urbanisation
The increase in the proportion of people living in urban areas. Although this can be caused by natural
increase (higher birth rates in urban areas than rural areas), it is more likely to happen because of rural-
urban migration.
Urban growth or Sprawl: A growth in the size of the urban area. This normally happens because of building
in the rural-urban fringe, although it may also include things like land reclamation.
Rapid urbanisation and urban growth can cause many problems in urban areas including:
Congestion (an increase in the amount of traffic leading to traffic jams).
Pollutions (air, water, noise, visual).
Electricity blackouts.
Water shortages.
Unemployment.
Growth of informal settlements.
Crime
Congestion in Harare
The problem of congestion is caused by multiple factors, including:
Increase in car ownership
Limited amount of public transport or expensive public transport or overcrowded public transport
Roads not designed for many cars
Population growth and rural-urban migration
The movement of freight (containers) onto lorries
Problems Caused by Congestion
As car ownership increases so does the amount of pollutants released by cars. This can lead increased
chest problems e.g. asthma.
People travelling to work have to leave home earlier and arrive back later, therefore spending longer
away from their families.
More cars on the roads increases the frequency of accidents
More vehicles on the roads increase the amount of air pollution, but also noise pollution.
Late deliveries caused by traffic jams costs companies and the economy money.
Workers also arrive late to work because they are stuck in traffic.
It creates a reliance on oil and more oil is used at slow speed than normal travelling speeds
Solutions
Pedestrianisation.
Improve rail links in town.
Car sharing
Reurbanisation: This means the movement of people back in the centre of urban areas (near the CBD).
By encouraging people back into the centre then commuter times and traffic jams should decrease.
Increased car tax and petrol duty.
Park and ride
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Rush hour: The period of time when most people travel to work. This normally between 7-9 in the morning
and 5-7 in the afternoon. Traffic is normally worst during these periods.
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TRANSPORT AND TRADE
Transport
Transport is the act of moving items and people from one place to another while communication is the
process of transferring information between individuals, groups and places.
1. Existence of sets of corresponding places with surplus (supply) and deficits (demand) for goods, services
and information.
2. Alternative sources may hinder transport e.g. a nearby source of market of a required commodity.
3. Infrastructure depending on how it is can lead to establishment of efficient or inefficient transport.
4. Politics where by the government may decide to be the leading provider of transport facilities.
Modes of Transport
There are 3 common modes of transport namely land, water and air transport.
Land Transport
-The type that involves movement of people and goods on land.
1. Human Porterage
-Movement of people from one place to another carrying light goods on their back, hands or shoulders or
by using hand carts, trolleys, bicycles or motorcycles.
2. Use of animals
-Use of domesticated animals to carry goods and people on their back or pull loaded carts (drought
animals).
Disadvantages
(a) Goods can be stolen or destroyed by wild animals and extreme weather conditions because they are
exposed.
(b) They are a very slow means of transport hence time consuming, tedious and boring.
(c) They can`t transport large quantities of goods because human and animal energy get exhausted with
time.
(d) They can cause congestion on busy urban roads which may delay other forms of transport.
3. Road Transport
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-Means of transportation of people and goods by motor vehicles on roads.
Types of Roads
(a) All weather roads- which are used all year round i.e. tarmac and murrum roads.
(b) Dry weather roads- which are used reliably during dry seasons.
(c) Motorable trucks- which are used by people on foot and by vehicles on dry season. A truck is a path or
rough road made by people, vehicles or animals.
-Africa Highway from the Port of Mombasa to Dakar in Senegal through east and Central Africa.
-Djamena Highway through Core De Ivoire , Nigeria and Chad.
-Sahara Highway from Lagos to Tripoli through Algeria.
Disadvantages
(a) Traffic congestion and jams when there are many vehicles on roads which leads to delays and fuel
wastage.
(b) Its expensive over long distances and when transporting bulky goods.
(c) Vehicles can carry a limited number of people and amount of goods at a time making them expensive
and uneconomical.
(d) It`s adversely affected by weather e.g. during heavy rains, roads become impassable and foggy
conditions hinder visibility making it easier for accidents to occur.
(e) Vehicles pollute the environment by their exhaust fumes and noise which they produce.
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Road Networks in Zimbabwe
Roads in Zimbabwe are grouped into wide – tarred and other roads.
Are classified using the A system (autobahn) where they vary from the best surfaced to not surfaced.
There are wide tarred roads in the central, north east and eastern parts of the country due to lot of
economic activities, more towns with large populations and the land is fair and easy to make roads.
Other roads link communal areas while wide tarred roads also link commercial areas.
Wide tarred roads crosses Zimbabwe`s boarders at six points e.g Chirundu, Mutare and Victoria Falls
for international trade and tourism.
High concentration of tarred roads are in Harare followed by Bulawayo.
Wide tarred roads are fewer because they are expensive to construct.
Other roads are in communal areas due to imbalances created during the colonial era.
4. Railway Transport
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Disadvantages
(a) Very slow means of movement especially of perishable and urgently required goods.
(b) Expensive to construct as much iron and steel is used to construct railway lines and trains.
(c) Inflexible in that railway lines aren`t available all over the country and their direction cannot be changed.
(d) Are affected adversely by terrain as where there are steep gradients, tunnels and winding tracks have to
be used which adds to the cost of setting up railway system.
(e) Specific gauge of railway line can only be used by a specific design of train unlike roads which can be
used by many varieties of vehicles.
(f) Trains can`t use rails while they are being constructed unlike roads which can be used while they are
being constructed, improved or even repaired.
Tazara railway- connects Zambia Copper Belt with the sea port of Dar-es-salaam.
Benguela Railway- runs from Zambia Copper Belt to Angola.
Kenya Uganda Railway- runs from Mombasa to Kisumu. It has an extension from Nakuru through
Eldoret to Malaba then through Tororo to Kampala.
Kenya‟s other railway branches are Voi to Taveta, Konza to Magadi, Nairobi to Nanyuki, Gilgil to
Nyahururu, Nakuru to Eldoret and Kisumu to Butere.
Administration by different colonial governments who constructed railway links only within areas of
their jurisdiction.
Political differences which led to mistrust and hostility which works against effort to construct railway
jointly.
Countries have railways of different gauges making connection to be difficult.
Little interstate trade which doesn`t warrant construction of railways to transport bulky goods.
Countries lack sufficient capital to establish railways.
Mountainous landscape and swampy terrain which hinder the development of rails to link the countries.
Competition from other modes of transport which are cheaper and flexible.
High maintenance and expansion costs causing little expansion of rail lines.
Mismanagement of rail services leading to deterioration at lower income.
Vandalism during political unrests and by people dealing in scrap metal.
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Was built in the late 1890s and early 1990s during political events.
Main railway line runs along the Central watershed from Bulawayo to Harare and Mutare.
Railway line are linked to other countries e.g. to Pretoria and Zambia for international trade.
Other line branch from the main route for specific reasons e.g. to move minerals and goods.
They are few railway line in the country because it`s expensive to build them.
Air Transport
Advantages
Very fast means of transport.
Can be used in case of emergency e.g. rescue operations in disasters such as floods.
Not affected by relief.
High value goods and perishables are carried fast.
Disadvantages
Prone to sabotage and terrorism.
Influenced by bad weather like smogs.
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Are designed for domestic and international travels.
Harare dominates international air routes due to being the capital city for holding international
conferences, nice hotels and bookings for tourists and large population/ market for airlines including
Air Zimbabwe.
Airlines also connects other towns and tourist resorts like Victoria Falls.
Zimbabwe`s airport are located far away from residential areas to avoid accidents and noise pollution.
Zimbabwe is trying by all means to upgrade its airways and handling facilities, purchasing high speed
aircraft with comfort and extending existing air ports.
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Beta Index(B.I.) of a transport network = Number of edges (E)
Number of nodes (N)
5. Pipelines
-Means of movement of fluid or gas products such as water, gas and oil through pipes from one place to
another. Pumping stations are constructed along the pipelines to keep the product flowing steadily.
Advantages of Pipelines
Disadvantages
(a) Selective in that they can be used to transport fluids and gasses and can transport only one type of
commodity at a time.
(b) Insecure in that they may be sabotaged if they run across a number of countries when there are political
differences or when one country decide to withhold the product.
(c) Pipelines may cause pollution if they burst spilling oil, gas or sewage and the problem would be grave
if it occurred under water.
(d) Inflexible in that they remain permanently in one position and rerouting becomes impossible and further
distribution of the substance from depots has to be done by roads and railways.
6. Water Transport
Cargo Liners
For carrying both goods and people.
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Have loading and unloading facilities.
Slower in speed.
Less prestigious.
Smaller in size compared to passenger liners.
Some carry different products while other carry specialised goods e.g. petroleum.
2. Tramps
- They are ships meant for transporting cargo.
-No fixed routes or schedules.
Advantages of Containerisation
(a) Safety and security because containers are sealed which protects goods from destruction by bad weather
and from being stolen.
(b) Easy to handle because containers are fitted with special devices like hooks and rings which makes
loading and unloading easy.
(c) Time saving because goods are put in one container than being carried in several boxes which makes
loading and unloading easy.
(d) It`s economical in terms of space because containers have a standard shape which reduces wastage of
space by allowing tight packaging of goods.
Are well marked routes through which Ocean traffic passes. They are also called ocean trading routes
because they have come about as a result of trading activities among various regions.
Major ocean routes are concentrated in the northern hemisphere due to the following:
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Inland Water Ways
a Way .
Examples of Lakes which are inland water ways are such as Victoria (largest inland waterway in E. Africa,
Tanganyika, Malawi, Albert and also man-made lakes such as Kariba, Nasser, Volta and Kainji.
Factors Which Have Hindered Development of River Transport in Africa
1. Inadequate capital to develop waterways, ports and for the purchase of vessels.
2. Fluctuation of water levels which makes sailing difficult as a result of rivers passing through dry areas.
3. Presence of rapids and waterfalls which hinders the vessels‟ movement.
4. Siltation of rivers which makes their channels shallow hence hindering movement of vessels.
5. Presence of floating vegetation which makes it difficult for vessels to sail due to narrowing of the river
channel.
6. Most rivers pass through unproductive zones hence it‟s uneconomical to develop river transport.
7. Rivers flow across political boundaries which may require negotiation in order for the countries involved
to use them for transport.
8. Inadequate technology.
Canal Transport
A canal is a water channel that is cut through land for boats or ships to travel along. Some canals join large
water bodies like seas and oceans.
Examples of Canals
Suez Canal which joins Mediterranean and Red Sea.
Panama Canal which connects Caribbean Sea with Pacific Ocean.
Dortmund-Ems Canal which joins R. Rhine to the N. Sea.
Soo canals which connects connecting L. Superior to L. Huron.
(a) Offers less friction to the movement of vessels as it‟s the case with roads.
(b) Are natural and free transport routes requiring less artificial infrastructures
(c) Less expensive because large loads can be carried at minimal costs and water routes require minimal
maintenance.
(d) It`s a reliable mode of transport since there is very little traffic congestion on waterways because the
waterway is large.
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(e) Goods are protected because they are transported in containers or tankers.
(f) It`s a safe mode of transport for delicate goods.
Disadvantages
(a) Many water ways are affected by water fluctuation like low volumes and high volumes which make
them to flow swiftly which make them unnavigable.
(b) Water transport is the slowest and unsuitable for perishables, casualties and medicines.
(c) Great loses are incurred during accidents such as fire outbreaks, typhoons, tsunamis and mechanical
breakdown due to the large carrying capacity of the vessel.
(d) High capital is required in the purchasing of modern shipping vessels and maintenance of parts.
(e) Ocean transport is available only to people who live near water ways unlike roads which are flexible.
(f) Insecurity in the oceans where pirates steal from and attack sailing ships.
(g) Sea vessels greatly contribute to water pollution as most of the wastes are thrown into the sea.
1. development of trade because buyers are able to move to markets, traders are able to move to market
centres where products are in high demand and order goods for sale without necessarily going to the
suppliers which reduces transport costs and hence increases profits.
2. Development of infrastructure by making tourist attractions accessible.
3. Promotion of industrial development/establishment of more industries since areas with good transport
networks are likely to attract investors to set up industries and finished goods are able to reach consumers
easily..
4. Many people are employed in the transport sectors e.g. drivers, mechanics and engineers.
5. Settlements develop where transport routes converge e.g. Khartoum at the confluence of blue and white
Nile and Mombasa.
6. Transport opens up remote areas for exploitation of natural resources such as minerals, fish, tourists‟
attractions because labour can be easily ferried to such areas and resources can be taken easily to processing
sites.
7. Transport is source of revenue to the government e.g. tax is levied.
1. Some countries are landlocked i.e. located far inland away from oceans e.g. Uganda, Rwanda, Burundi,
etc. the solution is to develop good relations among the nations in the continent so that countries which
have access to the sea permit their landlocked neighbours to have direct access to the sea routes.
2. Regions having rugged relief due to presence of features like mountains e.g. mountains Kenya and
Kilimanjaro which makes construction of roads and railways difficult and expensive. Presence of rapids
and waterfalls which causes swift movement of water makes development of river transport difficult. The
solution is constructing passes and tunnels through ridges and slopes and building of bridges across rivers
and valleys to allow construction of roads and railways.
3. Shortage of navigable rivers because rivers have navigable stretches, presence of obstacles and
fluctuations of water volumes, narrowness and shallowness all of which makes navigation difficult.
Solution is widening and deepening of river channels through dredging and construction of dams across
rivers to improve navigation.
4. Lack of adequate capital for establishment and maintenance of transport infrastructure e.g. vehicles and
locomotives.
5. Political instability in countries such as Somalia and Zimbabwe which have affected transport. Solution
would be to set peace mission in the affected countries in order to restore stability.
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6. High cost of travelling due to high cost of fuel causing the low and middle class persons to travel less
which reduces profits realised in the transport sector. The solution is management and conservation of
energy to save on the available resources and alternative sources of energy.
TRADE
Types of Trade
A. Domestic/Internal/Home/Local trade
-Buying and selling of goods within a country`s borders.
It`s classified into:
1. Wholesale Trade-purchasing of goods in bulk from producers and selling them to retailers.
2. Retail Trade-buying goods from wholesalers and selling them to individual consumers.
B. Regional Trade
-Trade between countries found in the same geographical region.
C. International Trade
Exchange of goods and services at the global level.
It`s classified into:
1. Export Trade-selling of goods and services to foreign countries. Examples of major exports are coffee,
tea, cotton and flowers
2. Import Trade-buying of goods and services from other countries. Examples of imports are crude oil,
vehicles, electronics, sugar, skilled labour, vehicle parts etc.
3. Bilateral Trade-exchange of goods and services between two countries.
4. Multilateral Trade-exchange of goods and services between many countries.
5. Visible Trade-trading in tangible goods.
6. Invisible trade-trading in services.
Balance of Trade
Balance of Payment
-Difference in value between visible and invisible exports and imports.
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4. Adequate and efficient means of transport and communication encourage trade because bulky goods can
be transported quickly and over long distances from producers to consumers. Poor transport discourages
trade due to the difficulty in getting goods to the market in time. Goods can be supplied faster when traders
communicate with suppliers without having to travel a lot which reduces travelling cost and hence
increasing profits.
5. Trade restrictions can encourage or discourage trade. They are of two types:
a) Tariffs- taxes or duties levied by a country on a particular type of commodity imported in order to
protect its domestic industries.
b) Quotas-specified quantities of goods which must not be exceeded during importation or exportation.
1. Employment creation.
2. It`s a source of revenue for the government by charging sales tax such as V.A.T. on manufactured
goods sold locally and tariffs at the point of entry into the country.
3. Foreign trade enables a country to earn foreign currency.
4. Leads to development of settlements e.g. many towns started as a small market and more people
moved there when trading activities increased.
5. International trade ensures availability of a wide range of goods for consumers.
6. It leads to development and improvement of transport infrastructure such as roads and railways.
7. Leads to development of industries because as the goods are bought demand for goods increases hence
more industries are set or existing ones increase their activities in order to satisfy the increased demand.
1. Zimbabwe depends on agricultural exports which are sometimes affected by climatic change, pests and
diseases leading to low production, and hence low foreign currency.
2. Zimbabwe`s exports are of low value as they consist of raw materials or semi processed commodities
which fetch low prices.
3. Local manufactures suffer unfair competition from foreign firms.
4. Unexpected trade restrictions are sometimes imposed on Zimbabwe`s exports
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5. Inadequate transport and communication as most roads are poor and impassable during rainy season
meaning goods can`t reach the market and hence increased costs for such goods.
Objectives of COMESA
(a) To reduce and eliminate trade barriers on selected commodities to be traded with member states.
(b) Abolish restrictions in administration of trade among member countries.
(c) Fostering relations, peace and political stability for member states.
(d) Raise the standard of living within member states.
(e) Promote goods being produced in the member states.
(f) Establish and foster co-operation in all fields of economic activity.
Achievements
(a) Increased volume of trade.
(b) Increased accessibility to markets in member countries.
(c) Free movement of goods among member countries due to elimination of trade barriers.
(d) Increased efficiency in production as each member is allowed to specialise in what she produces.
(e) Improvement of transport and communication facilities.
(f) Increased political and economic cooperation among member states.
It started as Southern African Development coordination in 1980 in Lusaka Zambia and transformed
into SADC after collapse of apartheid.
It has 15 member states e.g. Tanzania, DRC, S. Africa, Zambia, Zimbabwe, Mozambique, etc.
Objectives
(a) Encourage self-reliance among member states in the face of instability posed by apartheid regime of S.
Africa.
(b) Promote and defend peace and security.
(c) Promote regional integration.
(d) Eradicate poverty.
(e) Facilitate trade and economic liberalisation.
(f) Promote self-sustaining development on the basis of interdependence on member states.
(g) Promote and maximise utilisation of natural resources and effective protection of environment.
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Achievements
(a) Promotion of regional industries based on domestic and regional raw materials.
(b) Reliability and development of regional transport and communication infrastructure.
Objectives
Achievements
(a) Brought peace to troubled countries like Liberia and Sierra Leone.
(b) Promotion of trade in the region through the peace achieved.
(c) Development of schools to train people on peace keeping e.g. The National War College.
(d) Free movement of goods among member states.
Objectives
(a) Promote cooperation in economic, trade, social, security and judicial matters.
(b) Implementation of economic and monetary union.
Achievements
(a) Signing of many trade agreements between EC and other countries.
(b) Free trade among members as a result of abolishing trade barriers.
(c) High agricultural production as farmers receive guaranteed prices which have enabled them to increase
efficiency.
(d) Free movement of factors of production which include capital and labour.
(a) Civil wars taking place in some countries which has caused insecurity in turn affecting trade between
countries.
(b) Political differences among leaders of member states may affect cooperation among member states.
(c) Some countries produce similar goods making the volume of trade to be low and less rewarding.
(d) Free trade affects local industries as the imported goods without taxes are usually cheaper than locally
produced goods.
(e) Free trade denies countries revenue they would have earned from taxing imported goods.
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(f) Poor transport and communication limits inflow of goods and services.
(g) Some member states don`t remit their annual subscriptions which affects the operations of the
organisations.
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ENVIRONMENTAL PROBLEMS
Greenhouse Effect and Global Warming
Greenhouse gasses (GHG): Any gas that absorbs and emits radiation in the thermal infrared range. The
gases include: Carbon monoxide, carbon dioxide, methane, sulphur dioxide, Nitrous Oxide, water vapour
and ozone.
Sources of greenhouse gases include:
- Transport (cars and planes).
- Animals (cow release large amounts of methane)
- Burning fossils fuels (especially oil and coal)
- Melting Permafrost (methane is released when permafrost melts).
- Industry
- Domestic use (wood fires)
There are some natural causes of changes in climate including:
- Changes in the sun's solar radiation.
- Gases (sulphur dioxide) released from volcanoes.
- Dust and ash from volcanoes and meteorites blocking incoming solar radiation.
- Changes in the earth's orbit/axis, making earth close to or further from the sun
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- International Agreements: International agreements like the Kyoto Protocol should help limit the
amount of greenhouse gases being released into the atmosphere.
Adaptation: Changing lifestyles to suit new conditions.
- Build More Sea Defenses.
- Air con and/or Heating
- Improved Meteorology: Predict and track events (hurricanes, droughts, etc.) so that populations can be
warned and therefore prepare.
- Disease Treatment: If the strength of the sun's rays intensify diseases like skin cancer and eye cataracts
will increase. We will have to improve prevention (slip, slap, slosh) and improve treatment.
- Desalination.
Are there any Positive Impacts of Global Warming?
- Improved Arctic Navigation: Global warming will mean that the amount of Arctic ice steadily
decreases. As the ice melts navigation across the North Pole will become safer and quicker. Trade
between Scandinavia, Russia, Canada and US will all be a lot easier.
- Increased Agricultural Land: As permafrost melts and temperatures start to rise it will be possible to
grow more crops on more land. With a rising global population this might be vital in the fight to reduce
global famine.
- Reduction in Cold Deaths: Old, young and sick people are very vulnerable to the cold. If global
temperatures start to rise then latitudes further north and south will become more hospitable and less
people will die from the cold.
- Release of Freshwater: Currently a lot the world's freshwater is held in glaciers or as permafrost. As
global temperatures rise, we might be able to capture and use some of this freshwater to reduce the
effects of drought.
- Accessibility of Resources: It is believed that places like Greenland, Alaska, Siberia and Antarctica
contain a lot of resources (oil, gas, etc.). As global warming causes large areas of ice to melt they will
become more accessible for human exploitation.
- Reduced Heating: If global temperatures rise people will have to heat their properties less. Not only
will this save money but it will also reduce the demand for gas and electricity and therefore reduce the
amount of greenhouse gases being released.
Acid Rain
Acid rain can take two forms, wet deposition and dry deposition. Wet deposition is when pollutants mix
with rain water and fall to the ground as acidic precipitation. Dry deposition is when pollutants and
particulates fall to the ground without mixing with rain water. Some acid rain has had pH levels as low
as 2.
Sulphur dioxide and nitrous oxides are the two main chemicals that react with water to make acid rain.
The chemicals are commonly released from power stations, factories and transport.
Acid rain can cause many problems including:
Damage to buildings.
Metals (iron, aluminum, etc.) dissolved by acid rain can be washed into water courses.
Vegetation can be damaged and growth reduced.
Lakes and rivers can become acidic harming the ecosystem and aquatic life.
Soil acidity increases.
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Dry Deposition: When acid falls directly back to earth without mixing with precipitation. This tends to
happen close to source.
Wet Deposition: When acids are dissolved in precipitation and fall to the ground as acid rain.
The Ozone Layer
The ozone layer is a layer of gas (mainly ozone O3) high in the Earth's atmosphere (20-30km up). The
ozone layer helps to protect humans from the sun's harmful ultraviolet solar radiation (it absorbs up to 99%).
The existence of the ozone layer was first discovered in 1913. The ozone layer can be damaged by chemicals
and gases including; nitrous oxide, bromine and chlorine. Although all occur naturally the amount of
chlorine and bromine were increasing because of the human use of CFCs (chlorofluorocarbons) and
bromofluorocarbons. CFCs were being used in products like: aerosols, packaging, fridges and refrigerators,
air con and solvents
Even though it was known that the ozone layer could be damaged, it was not until 1985 when holes were
discovered over the poles that serious action was taken. This meant that more of the sun's harmful ultraviolet
radiation was reaching Earth causing more disease (skin cancers and cataracts) and damage to vegetation.
Because of the depletion of the ozone layer, countries started to ban the use and production of CFCs. USA
and Norway were the first to ban in 1978 and then in 1985 the Montreal Protocol (now signed by 160
countries) severely limited the production of CFCs. After 1996 only recycled CFCs could be used. Since
the banning of CFCs the rate of depletion is believed to have slowed.
REFERENCES
1. Bunnet, R.B. (2011) Physical Geography in Diagrams for Africa. Longman Group Ltd. UK.
2. Gocha, N.T., Moyo, S. N.T., Ncube, R. and Nembaware, L. (2007) Dynamics of O`Level: Human and
Economic Geography. College Press. Harare.
3. Dzoma, G. (2015) ZIMSEC Geography Online Free Notes.
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