River Landscapes (Edexcel IGCSE Geography)

Revision Note

Bridgette Barrett

Written by: Bridgette Barrett

Reviewed by: Jenna Quinn

Upland Landforms

River landscape characteristics

  • The changes in river channel characteristics, lead to changes in the river landscape

  • The upland and lowland areas of rivers have distinctive landforms

  • Upland:

    • Waterfalls

    • Gorges

    • V-shaped valleys

    • Interlocking spurs

Waterfalls and gorges

  • Waterfalls form when there is a drop in the river bed from one level to another

  • This drop is often due to changes in the hardness of rock, where hard rock overlies soft rock

  • Hydraulic action and abrasion are the main erosional processes:

  • The soft rock erodes quicker, undercutting the hard rock and creating a plunge pool

  • This leads to the development of an overhang of hard rock which eventually over time, collapses 

  • The overhang falls into the plunge pool increasing abrasion and making the plunge pool deeper

  • The process then begins again and the waterfall retreats upstream leaving a steep-sided gorge

waterfall formation
Waterfall formation

V-shaped valleys 

  • Vertical erosion is dominant in the upper course of the river

  • This cuts down into the river bed and deepens the river channel 

  • Weathering and mass movement leads to material from the valley sides collapsing into the river forming a steep v-shaped valley

Formation of v-shaped valley
Formation of a v-shaped valley

Interlocking spurs

  • In the upper course of the river, the channel starts to meander

  • Erosion happens on the outside of the bend

  • In the upland areas this forms interlocking spurs

formation of interlocking-spurs
Interlocking spurs

Worked Example

Explain the formation of a waterfall.  (4)

  • Identify the command word

  • The command word is 'explain'

  • Your focus is on 'waterfall'

  • Answer: (you should include 4 points from the following)

  • Waterfalls occur where there is a step in the landscape often where hard rock such as dolerite overlays soft rock such as limestone (1)

  • The soft rock erodes due to hydraulic action, at a faster rate than the hard rock (1) leading to undercutting and the formation of a plunge pool (1)

  • This leaves an overhang of hard rock which eventually collapses due to gravity (1)

  • The process is then repeated causing the waterfall to retreat upstream leaving a steep side gorge (1)

Lowland Landforms

  • Lowland:

    • Meanders

    • Ox-bow lakes

    • Floodplains

    • Levees

Meanders 

  • In lowland areas lateral erosion is dominant

  • Meanders increase in size

  • The fastest water flow (thalweg) is on the outside of the river bends, leading to erosion:

    • The erosion undercuts the river bank forming a river cliff

    • The river bank collapses and the edge of the meander moves further out

  • The slowest flow is on the inside of the river bends, leading to deposition:

    • The deposits form a slip-off slope

  • Deposition on one side and erosion on the other leads to the meander migrating across the valley

meander-cross-section
Cross-section of a meander

Oxbow lakes

  • With distance downstream the size of the meanders increase

  • The erosion on outside bends can eventually lead to the formation of a meander neck

  • At a time of flood, the river may cut through the neck of the meander forming a straighter course for the water

  • The flow of water at entry and exit from the meander will be slower, leading to deposition

  • The meander becomes cut off from the main river channel, forming an oxbow lake

oxbow-lake-formation
Oxbow Lake Formation

Examiner Tips and Tricks

Remember when describing the formation of oxbow lakes it is important to state that the river will break through the neck of the meander during a flood. At other times the river does not have enough power to break through.

Floodplains and levees

  • Floodplains are flat expanses of land on either side of the river

  • The migration of meanders leads to the formation of the floodplain

  • High discharge may cause the river to overflow the banks

  • More of the water is in contact with the land surface as the water spreads across the floodplain

  • Increased friction reduces velocity and material is deposited across the floodplain gradually increasing the floodplain height

  • The heaviest material is deposited first nearest to the river channel forming natural embankments called levees

floodplain and levee-formation
Floodplain and Levee Formation

Examiner Tips and Tricks

When describing landform formation it is helpful to write the formation down as a sequence of steps. This will make the process easier to remember.

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Bridgette Barrett

Author: Bridgette Barrett

Expertise: Geography Lead

After graduating with a degree in Geography, Bridgette completed a PGCE over 25 years ago. She later gained an MA Learning, Technology and Education from the University of Nottingham focussing on online learning. At a time when the study of geography has never been more important, Bridgette is passionate about creating content which supports students in achieving their potential in geography and builds their confidence.

Jenna Quinn

Author: Jenna Quinn

Expertise: Head of New Subjects

Jenna studied at Cardiff University before training to become a science teacher at the University of Bath specialising in Biology (although she loves teaching all three sciences at GCSE level!). Teaching is her passion, and with 10 years experience teaching across a wide range of specifications – from GCSE and A Level Biology in the UK to IGCSE and IB Biology internationally – she knows what is required to pass those Biology exams.

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