GEOGRAPHY NOTES

WATER RESOURCES AND PLAINS AND RIVERS:

What is a plain?
 Definition: Plains are wide, flat, or almost flat areas with
gentle slopes.
 Eurasian Steppe: One of the largest plains, found in a
temperate climate with little rain.
 Great Plains: Another vast plain region in North America,
characterized by similar climatic conditions.
What are plains like?
 Types and Features: Different types of plains are
characterized by their climate, vegetation, and location.
 Great Plains & Indus River Plain: Examples include the Great
Plains, near mountains, and the Indus River Plain in Pakistan,
which is fertile and slopes from the Himalayas to the Arabian
Sea.
 Coastal Plains: These plains are found along the coasts of
continents.

Grass Lands:
 Growth Conditions: Grasslands receive enough rain for
grasses to grow up to 1 meter high, with scattered trees in
wetter parts.
 Regional Names: Grasslands have different names in various
regions: prairies (North America), pampas (South America),
and savannahs (Central Africa, Australia, southern North
America).
 Vegetation: Savannahs consist of grass, small flowering
plants, and a few trees.
Deserts:
 Deserts as Plains: Some plains are deserts, characterized by
less than 250 mm of rainfall annually.
 Climate and Vegetation: Deserts are usually hot during the
day and cool at night, with very little vegetation due to the dry
climate.
 Location: Most deserts are located between 20° and 35°
north and south of the Equator, such as the Thar Desert in
Pakistan and the Sahara Desert in North Africa.
 Desert Plains: Examples of desert plains include parts of
Australia.
 Temperate Deserts: Found in higher latitudes, these have
dry environments due to high mountains and distance from
the sea.
 Examples of Temperate Deserts: are Central Asia, western
North America, southeastern South America, and southern
Australia. Katpana Desert in Pakistan is a cold desert.
 Aridity and Landforms: Both hot and cold deserts are similar
in aridity, landforms, and soil.

Artic Tundra:
 Tundra Plains: These are plains in the Arctic region where
the ground is frozen.
 Permafrost: The frozen ground, called permafrost, can be up
to 450 meters thick.
 Soil Conditions: In the coldest tundra plains, the soil surface
remains frozen. In warmer tundra plains, the surface thaws in
the summer.
 Rainfall and Water: Tundra plains receive very little rain, but
melted ice forms bogs and shallow lakes in the summer.
 Vegetation: Few trees grow in tundra plains, but many small
plants can survive.

Flood plains:
 Floodplains: Plains formed by river sediments, regularly
flooded, flat lands next to rivers. Rivers like the Indus and the
Nile form floodplains.
 Sediment and Fertility: Flood waters bring nutrient-rich
sediments, making the soil fertile, and beneficial for
agriculture.
 Indus River: Originates near Mansarovar Lake in the Tibetan
plateau, runs through Pakistan, crucial for agriculture and
settlement in Punjab and Sindh.
 Importance: The Indus River is critical for agriculture, food
production, and industries in Pakistan, especially in areas with
scarce rainfall.

Source of a river:
 River Source: The starting point of a river, which can be a
lake, glacier, or spring on high land.
 Spring Formation: Springs form when groundwater pushes
to the surface through holes or weak rocks.
 Stream to River: The spring becomes a stream that flows
downhill, carrying sediment and cutting v-shaped valleys.
 Interlocking Spurs: Spurs are hard rocks that change the
stream's direction, creating interlocking spurs.
 Upper Course: The upper course of a river features fast-
flowing water and v-shaped valleys.
 Tributaries of Indus River: The Indus River's tributaries in
Punjab are the Jhelum, Chenab, Ravi, and Sutlej, originating
from streams, snow, and glaciers in the Himalaya, Karakoram,
and Hindu Kush mountains.
Upper course:
1. River Current: The movement of water in a river is known
as the current, which is usually strongest near the river’s
source.
2. Impact of Storms: Storms can increase the current's
strength, enabling it to move large boulders.
3. Erosion: Broken pieces of rocks scrape and dig into the
riverbed, causing the river to erode rocks and soil along
its path and carry them downstream.
4. V-Shaped Valleys: The river carves narrow, V-shaped
valleys and creates rapids, waterfalls, and gorges.
5. Gorges and Canyons: A gorge or canyon is a deep valley
that a river has cut.
Damns:
 Purpose of Dams: Dams are man-made structures built to
control the flow of rivers, creating reservoirs to store and
release water in a controlled manner.
 Indus Plain Uses: The Indus Plain supports diverse activities
such as farming, settlements, industrial setups, fishing, and
irrigation.
 Tarbela Dam: The largest Earth-filled dam in the world,
located in Khyber Pakhtunkhwa, Pakistan. It helps with
irrigation, hydroelectricity, flood control, and water supply.
 Economic Impact: The construction of new dams like
Diamer-Bhasha, Naulong, Kurram Tangi, Nai Gaj, and Dawarat
in Pakistan aims to boost agriculture and industry.
 Environmental and Social Impact: Dams can cause
displacement of people, disrupt ecosystems, affect
groundwater, and block water progression to other regions.
 River Nile's Aswan High Dam: Located at the border
between Egypt and Sudan, it controls annual river floods.
The middle course of a river:
 Floodplains: The river flows across wide flat lands called
floodplains, collecting more water and energy from streams
and other rivers, cutting a deep, wide channel.
 River Bends and Cliffs: The river flows around high ground
made of hard rock, creating bends. Water on the outside of
the bend flows faster, cutting a cliff on the riverbank.
 Middle Course: In the middle course, the river carries a
higher volume of water, with less steep angles due to lateral
erosion. This widens and deepens the river channel, reducing
friction and increasing water flow speed.
 Meanders: The river forms large bends, known as
meanders, through both deposition and erosion. Meanders
gradually migrate downstream, creating river cliffs on the
outside of bends and slip-off slopes on the inside.
 Oxbow Lakes: Over time, the horseshoe-shaped meanders
become slimmer with deposition. During floods, the river can
cut off the loop from the main channel, forming an oxbow
lake.
Lower Course:
 Delta Formation:
 At the river's mouth, it spreads across a plain and splits
into smaller branches, forming a delta.
 Deltas form because the river deposits fine material in its
lower course instead of flowing directly into the sea.
 Sediment Deposition:
 As the river flows a long way, it collects sediment.
 In the upper course, faster-flowing water carries
sediment. In the lower course, the flat surface slows the
water, causing sediment deposition.
 Sediment heaps up if deposited more quickly than the
sea can remove it, causing the river to split around these
heaps.
 Examples:
 The Indus River forms a delta at its mouth on the Arabian
Sea.
  The Nile River also forms a delta at its mouth on the
Mediterranean Sea.
 Estuary Formation:
 In areas with strong tidal action, sediments are arranged
widely, forming an estuary where river water mixes with
seawater.
 Slow-flowing water deposits sediment on the riverbed or
seabed, sometimes carrying it out to sea and depositing it
along the coast.
Rural and urban settlements on plains:
 Population Distribution: While over half of the world's
population lives in urban areas, the majority of Pakistanis still
reside in rural areas.
 Rural Lifestyle: In rural areas, people engage in farming,
labor, and sustainable businesses like tourism, fish farming,
and organic farming.
 Upper Indus Plain: The largest plain in Pakistan, it joins five
tributaries in Panjnad, flows as one in Sindh, and drains into
the Arabian Sea at the delta.
 Central Luzon Plain: The largest plain in the Philippines,
known as the "Rice Bowl of the Philippines" for its significant
rice production.
 Urban Attraction: Urban areas attract people from rural
areas due to better education, job opportunities, transport
routes, healthcare, etc.
River habitats:
 Habitat Definition: A habitat is where organisms naturally
live or grow, including microscopic living things in various
parts of a river environment.
 River Biodiversity: Rivers impact the biodiversity of a place,
providing various habitats for plant and animal life throughout
different seasons and stages of life.
 Ecosystem: An ecosystem is a collection of interdependent
living things.
 Pakistan's Rivers: Many rivers in Pakistan drain into the
Arabian Sea, with the Indus River having significant wetlands
along its course, from glaciers and high-altitude lakes to flood
plains and coastal wetlands.
Types of Wetlands
• Marine (coastal wetlands including lagoons,
rocky shores and coral reefs)
• Estuarine (deltas, tidal marshes, and
mangrove swamps)
• Lakes and the land around them
• Riverine (wetlands along rivers and streams)
• Marshes (swamps and bogs)
Importance of Wetlands:
 Water Storage: Wetlands store water, helping to make up
for shortages in reservoirs, natural lakes, and marshes.
 Fibre and Fuel Production: Wetlands support the production
of logs, fuel wood, peat, and livestock fodder from mangroves;
they also have suitable land for growing rice.
 Reducing Global Warming: Wetlands act as carbon sinks,
helping to contain greenhouse gases.
 Water Table Refill: They refill water table supplies.
 Pollution Breakdown: Natural processes in marshes and
swamps break down organic pollution, although they cannot
handle large amounts of untreated waste.
 Erosion Control: Wetlands control erosion by holding soil
and sediment, creating fertile soil when temporary lakes dry
out, and reducing erosion during floods.
 Flood and Storm Protection: Floodplains and marshes
protect from floods and storms; mangrove forests and coastal
wetlands hold back floodwater from tsunamis.
 Habitat for Pollinators: Wetlands provide habitats for
pollinators like bees and other insects, essential for plant
reproduction and honey production from mangroves.
Indus Dolphin:
 Indus River Dolphin: The Indus River dolphin is one of the
world’s rarest mammals and is a freshwater species found only
in the Indus River in Pakistan and River Beas in India.
 Habitat and Adaptation: These dolphins live in the lower
parts of the river's course, where they have adapted to muddy
waters. They feed on crustaceans like prawns and fish such as
carp, catfish, and gobies.
 Echolocation: Indus dolphins are blind and use echolocation
to navigate, similar to bats.
 Population Decline: There are only about 2,000 Indus River
dolphins left, with their population declining due to water
pollution, reduced habitat, entanglement in fishing nets, and
poaching.
 Conservation Efforts: The Indus River dolphin is protected as
an endangered species, and organizations like the World
Wildlife Fund Pakistan are studying and working to protect
them by collaborating with local communities to reduce
pollution and preserve their habitat.
Changing plains and rivers:
 Historical Settlements and Floods: Settlements have
historically flourished along riverbanks, despite rivers' routine
flooding and abrupt course changes known as avulsions.
 Sediment Deposition: Over time, rivers deposit sediment at
avulsion sites, creating features like alluvial fans, which have a
characteristic triangular shape.
 River Flow and Tectonic Activity: Rivers like Sutlej, Ravi,
Chenab, and Jhelum flow westward into the Indus River and
the Arabian Sea, but research suggests they once flowed
eastward into the River Ganges and the Bay of Bengal. This
shift was likely due to the collision of the Indian and Eurasian
tectonic plates.
 Avulsion Sites on Deltas: Avulsion sites can move due to sea
level rise, potentially exposing new areas to flood risks.
Climate change and human activities, such as deforestation
and converting forests to farmlands, increase sediment loads
and flooding risks.