River Erosion
Abrasion
Hydraulic Action
Attrition
Solution
Solution
Traction
Saltation
Solution
Upper Course
Deep V-shaped valley
Shallow channel
Rough channel
Lower speed of water
Waterfalls
Vertical erosion
Victoria Falls
Waterfall retreat
Plunge Pool
Gorges
Load grinds against
channel sides and bed
Water surges into joints. Its
force breaks, loosens rocks
Rock fragments collide and
wear down, become smoother
and rounded
CaCO3 + H2O
Gravel moves by a series of
jumps along river bed
Boulders slide and roll along
the river bed
2006/Sec 3 Core Geography/Sequencing Task: Rivers
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Potholes
Middle Course
Wider channel
Asymmetrical channel
More discharge
More open valley
Meander
River cliff
Slip off slope
Lower Course
Wide, flat valley
Highest discharge
2006/Sec 3 Core Geography/Sequencing Task: Rivers
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2006/Sec 3 Core Geography/Sequencing Task: Rivers
Prepared by LeongKL, SCGS
Largely depositional
Flood plains
Levees
Ox-bow lakes
Deltas
Cut-off
Slack water
Rapid flow
Wide, low-lying area found
on both sides of river
River flows over less
resistant rocks; carrying
out weathering
Concave bank
Natural embankments
made of coarse deposits
Erosion on concave bank;
deposition on convex bank
Convex bank
No large lakes to trap
sediments
Coarser material deposited
first because of increased
friction
River Nile
Coastal waters are quiet;
few strong currents
Larger wetted perimeter;
loss in river energy
HEP
2006/Sec 3 Core Geography/Sequencing Task: Rivers
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Fertile alluvial soil
Flooding
Dendritic
Silting
Irrigation
Trellis
Radial
Centripetal
Silt trapped. Lower course
does not receive natural
fertlisers
River Transport
Regulate water level
throughout the year
Greater erosion in
downstream portion of
river
Permeable surface
Tourist attraction, e.g.
Lake Nasser in Egypt
Irrigation water kill plants
because of increased
salinity
Gentle rising limb
Flood prevention
Loss of biodiversity due to
widespread flooding
Vegetation
Storm hydrograph
2006/Sec 3 Core Geography/Sequencing Task: Rivers
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Urban city
Higher peak discharge
Longer lag time
Steeper rising limb
Gentle recession limb
Shorter lag time
2006/Sec 3 Core Geography/Sequencing Task: Rivers
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A sudden fall of water
along the course of river
Develop when waterfall
retreats upstream
Lateral erosion and
undercutting occur on
concave bank
When river flows over a
band of resistant rock to
less resistant rock
Backsplash of turbulent
water undercuts the cliff
face of less resistant rocks
Deposition occurs on
convex bank because of
slack water
Resistant rock that lies
downstream erodes faster
than resistant rock
Overhanging cap rock
loses support and
collapses
Continuous erosion and
deposition on banks
Differential erosion causes
a change in gradient of
river
As this continues, the
waterfall retreats
Pronounced meander with
two concave banks getting
closer
Loss of support for
overhanging resistant rock
A narrow, deep valley with
almost vertical sides is
formed
Cut through by lateral
erosion on both banks or
strong currents
2006/Sec 3 Core Geography/Sequencing Task: Rivers
Prepared by LeongKL, SCGS
Straight channel,
abandoned meander loop
Lower Course
Overcome friction; little
energy for erosion
Deposition seals off cut-off
from river channel
Upper Course
Wider, deeper
channel
Ox-bow lakes
Small, narrow,
rough channel
Asymmetrical
channel
Waterfalls
Low volume of
discharge
Greater volume of water
than upper course
Floodplains
Deep, narrow,
steep-sided valley
Gentler gradient
2006/Sec 3 Core Geography/Sequencing Task: Rivers
Prepared by LeongKL, SCGS
More open V shape
valley
Widest, deepest
channel
Wide, flat-bottomed
valley
More lateral erosion; some
transportation and
deposition
Greatest volume of
discharge
Mainly depositional
Little vertical erosion,
more lateral
Weathering helps to
widen valley
2006/Sec 3 Core Geography/Sequencing Task: Rivers
Prepared by LeongKL, SCGS
2006/Sec 3 Core Geography/Sequencing Task: Rivers
Prepared by LeongKL, SCGS