GEOGRAPHY PAPER 1

geomorphology
Fluvial processes
*the physical interaction of flowing water and the
natural channels of rivers and streams*
River profiles:
*a graphical representation showing a river’s gradient
and shape from its source to its mouth and at a specific

points along its course*

Cross/transverse profile:
*view of river from bank to bank*
A cross profile shows a cross-section of a river’s
channel and valley at a certain point along the river’s
course.

A= upper course
- As the river flows downhill there is an increase in
vertical erosion.
- V-shaped valleys
- Waterfalls and rapids
- Channel is shallow and narrow because there is not
a lot of water in the channel
B= middle course
- As the river flows in the middle course, there is
some vertical erosion but more lateral erosion
- Channel is wider and deeper
- River starts to meander
- U-shaped valley
- Slope is gradual/steep
- Velocity of water is lower
C= lower course
- In the lower course there is a lot less erosion, with
only some lateral erosion
- Channel is at its widest and deepest
- Open U-shape
- As it meanders it creates 2 alternating banks:
- Slip off bank that is steep because of erosion
- Slip off inner bank that is gentle because of
deposition
Longitudinal profile:
*side view of a river from source to mouth*
Shows the rivers elevation change from the source to
the mouth, typically in a smooth, concave curve
A= upper course
- Vertical erosion deepens the valley
- Straight stream channel with short non-perennial
streams
- Turbulent flow due to uneven riverbed and valley
slopes
- Large stream load with big boulders (traction load)
B= middle course
- Vertical erosion decreases and lateral erosion
domintes
- Channel becomes wider
- River starts to meander
- Tributaries join the mainstream, increasing the
volume and erosive power
- Laminar and turbulent flow
- Load becomes smaller due to attrition and abrasion
(saltation load)
C= lower course
- Deposition dominates
- Channel is at its widest
- Laminar flow dominates due to smooth riverbed
and sides
- Very large load but smaller particles (suspension
and solution load)
*suspension = fine, light sediments
*solution = minerals and chemicals dissolved into
the water
Plan view of each profile:

Fluvial features:
Meander:
*a distinctive curve or loop in the course of a river
channel*
Formation =
1. Middle course has more energy and a high volume
of water (bcs of tributaries joining)
2. Lateral erosion starts to widen the river
3. As the river erodes laterally it forms large river
bends, and then horseshoe-like loops form
4. Due to deposition and erosion
-2 slopes develop at the meander lope
1) Undercut slope: outer bank, slope is concave, river
flows faster, erosion occurs, area is deep
2) Slip-off slope: inner bank, slope is convex, river flow
is slower, deposition occurs, slope is shallow
Cross section of a meander
Significance=
o Vital for river management
o Helping to mitigate flooding and erosion
Oxbow lake:
*a U-shaped, free standing body of water formed when
a meander is cut off from the main river channel*
Formation=
1. As the river meanders it creates two alternating
banks
2. Water erodes on the outer bank and deposits on
the inner bank
3. Causes the horseshoe to become tighter over time,
until the ends are very close together
 4. During heavy rainfall and flooding the water fails to
follow the meander and under-cuts the banks
5. As more erosion takes place on the outer banks,
the meander neck narrows and an oxbow lake is
cut off from the main river
Significance=
o Can be rich wildlife habitats
o Can be utilised for agricultural purposes, especially
crop farming
o Tourist attraction
Impact=
 Reduce downstream flooding by storing floodwater
temporarily
 Provides opportunities for recreation
 May increase mosquito breeding, leading to health

concerns

Braided stream:
*a stream consisting of multiple small, shallow
channels*
Formation=
1. Sediment load is deposited as shifting islands or
bars between the channels
2. When the river’s carrying capacity is exceeded the
river deposits its load into the channel
Significance=
o Source of water for crop farming
o Silt deposits form fertile soil
o Area hampers the construction of infrastructure
Impacts=
 Creates diverse habitats for fish, birds and plants
 May destroy crops or farmland during floods and
erosion
 Sometimes attracts tourists

Flood plains:
*a wide, flat area of land surrounding a river that
continuously floods*
Formation=
1. Floodplains form due to mainly deposition
2. Because of the gentle gradient, there is more
deposition occurring
3. The heavier load is deposited closer to the banks of
the river
4. Lighter and smaller load is dropped further away
from the river banks
Significance=
o Provide fertile land for agriculture
o Easy to construct infrastructure
o Beneficial for wildlife by creating a variety of
habitats for fish and other animals
Impacts=
 Can lead to loss of crops and farmland during
floods
 Risk to human life (during floods)
Natural levee:
*natural embankments(raised river banks) which are
formed when a river floods*
Formation=
1. Formed by the repeated flooding of a river
2. When the river floods, the biggest, most coarse
material will be deposited
3. This will be close to the river banks
4. The banks form levees made of sediment, silt and
other materials because of the repeated deposition
on the river banks
Significance=
o Provide a measure of protection from invaders
o May be used to increase available land for
habitation
o Usually parallel to the way the river flows, so can
help direct the flow of the river
Impacts=
 May trap water on the floodplain after floods,
causing water logging
 Restricts natural flooding, reducing nutrient
deposits on surrounding land
Waterfalls:
*an area where water flows over a vertical drop or a
series of steep drops in the course of a stream or river*
Formation=
1. Often in the upper course where. The river flows
over different layers of rock
2. Soft rock erodes more quickly, undercutting the
hard rock
3. Hard rock is left overhanging and because it is not
supported, it eventually collapses
4. The fallen rocs crash into he plunge pool. They
swirl around, causing more erosion
5. Over time, this process is repeated, and the
waterfall moves upstream
6. A steep-sided gorge is formed as the waterfall
retreats
Significance=
o Attract tourists
o Strong currents are often used to generate hydro-
electricity
o Form a barrier to infrastructure development
Impacts=
 Provide opportunities for a wide range of outdoor
leisure activities
  Fishing can be carried out on waterfalls

Rapids:
*areas of shallow, fast-flowing water in a stream.
Stretches of fast-flowing water grumbling over a rocky-
shallow riverbed*
Formation=
1. Water goes from one hard rock to softer rock
2. Rock layers below the water are exposed
3. Flowing water splashes ver and around the rocks,
forming what is called ‘white water’
Significance=
o Attracts tourists who want to raft down the stream
o White water dissolves oxygen
o Oxygen is useful to the ecosystem around the
stream
Impacts=
 Makes river difficult to navigate for transport routes
  Increase erosion of riverbeds and banks in some
areas
 Limit agricultural or settlement use close to the
river due to safety risks

Deltas:
*landform at the mouth of a river, where different
channels of the same river flow into an ocean or sea*
Formation=
1. River slows down at the mouth due to silt deposits
and gentle gradient
2. The channel splits into several smaller channels
and it loses velocity
3. As the river loses velocity it deposits its load on the
riverbed
4. Both the bed load and suspended load are
deposited producing fertile alluvial land
Significance=
o Important industrial hubs
o Are a source water
 o Usually highly fertile areas and support extensive
crop cultivation
Impacts=
 Important for fishing and aquaculture industries
 Serve as transport hubs and trade centres near
coasts
 Prone to flooding and storm surges, especially from
cyclones/ tsunamis

River grading:
*the balance between rate of erosion and rate of
deposition8
a. Graded rivers = there is a balance between erosion
and deposition
b. Ungraded rivers = either erosion or deposition
dominates
Process=
 Downward/vertical erosion dominates in the upper
course cuing a steep valley slope
 Headward erosion removes temporary base levels
of erosion in the upper course
  Downward/vertical erosion removes temporary
base levels (waterfalls) in the upper course
 This material is then transported downstream
 Discharge of the river increases in middle course
causing lateral erosion
 Gradient in the middle course becomes less steep
 Deposition dominates in the lower course because
the gradient is gentle
 Deposited materials fill up lakes and dams
 The river profile will now develop a concave shape
from upper to lower course
 Equilibrium between erosion and deposition will
maintain [result in] a graded profile
Distinguish between the two streams =

Base level of erosion;

 Permanent base level = lowest level to which a
river can erode
 Usually sea level
  Temporary/local base level = features/ structures
delay further erosion
 Causes a knick point in the profile, making it
ungraded
 Human-made; dams
 Natural; lakes, rapids

River rejuvenation:
* when a river regains its erosive power*
Reasons=
 Drop in sea level
 Increase in rainfall
 Stream piracy/ river capture
 Isostatic uplift
 Decrease in stream load
Features=
1. Terraces: forms as a result of downward erosion,
floor of old valley forms a terrace on either side
2. Valley in a valley: new valley is carved into old
valley
3. Entrenched meanders: ores from a meandering
river that has cut a deep valley into the underlying
bedrock
Importance=
 Landforms are good for tourist attractions
 Water at Knick point waterfalls can be used for
power generation
 Old flood plain suitable for crop farming
 Land is too limited
  Water is too far for irrigation
 Land can be steep and cause accidents
River capture/ stream piracy:
*When the more energetic river, captures som of the
water of a less energetic river*
- river A is flowing towards west but eroded headward,
cut through the watershed and captured river B that

was flowing northeast

Abstraction =
*process whereby the watershed becomes lower and its

position shifts*

Headward erosion =
*stream erodes away at the rock and soil at its
headwaters in the opposite direction that it flows*
-lengthens the stream channel and enlarge the
drainage basin

1. Erosion takes place towards the source of the river

2. Headwaters of a river are moving upstream
3. Upper stream is moved backward
4. Undercutting of upper reaches river
5. Less resistant rocks promote the erosion process

Features=
1)Captor stream – energetic stream that intercepts
the water of the less energetic stream.
2)Captured stream – river from which the after was
intercepted by the captor stream.
3)Misfit stream – stream that has lost its water, also
called beheaded stream. The river is too small for
the valley it flows in.
4)Elbow of capture – place at which stream piracy
tales place. Usually a knickpoint waterfall develops.
5)Wind gap – dry river valley between the misfit
stream and the elbow of capture.

Impacts=
Captor stream –
o Volume of water increases
o Downward erosion increases
o Carrying capacity increases
o River rejuvenates
Captured stream –
o Volume of water decreases
o Less erosion , wind erosion will occur
o Carrying capacity is reduced
o Stream too small for its channel
Implications of river capture=

Superimposed and antecedent drainage patters:

Superimposed=
*drainage pattern that has been established on an
earlier surface*
-rivers are younger than structures across which they
cut
-may cut narrow gorges if forced across bands of hard
rock

Causes:
 The development of drainage Bain on a
softcover of oak that is later eroded to expose
harder, older rock
 The rivers erosive power being strong enough
to cut rough the resistant rock while
maintaining its original course

Antecedent=
*where a river developed its course before the high-
lying area as formed*
-river is older than the landform across which they cut
-warping, folding or faulting occurred
-may cut narrow gorges if forced across bands of hard
rock

Causes:
 The initial establishment of a pre-uplift river
course that has the erosive power to resist the
subsequent changes in the land