Stream Channel Processes:
Go to the IGCSE WIKI page on River Processes and use the resources there to revise the processes occurring in a river. Make sure that you know the different processes of Erosion, Transport and Deposition.
The Hjulström Curve:
More information on Fluvial Processes can be found on the S-cool site.
Exam Questions:
Describe two processes involved in the transport of a river’s load. [2+2]
Explain how stream discharge is related to channel size and shape. [6]
The Rivers Profile:
landforms_in_the_upper_course.ppt landforms in the middle and lower course of a_river.ppt
Features of Erosion and Deposition:
Meander
Meander Formation from jezbo16
Braided Stream
Levees:
Deltas
River Terraces:
Waterfall:
Summary:
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| Click on the image to be taken to an excellent summary of Fluvial Process and Landforms from the British Geographer. |
Exam Question:
To what extent do you agree that river landforms can be classified as either erosional or depositional? [10 marks]
Human Modification of Floodplains:
Urban Hydrology:
8. Human Modifications to Floodplain.pptx
Human Modifications (Urban Hydrology): Humans can change the hydrology of rivers in many ways. Below is a summary of some of the most common.
Urbanisation: Urbanisation tends to cause deforestation reducing interception and transpiration. Sewers also reduce surface stores and therefore evaporation. Urban areas usually create large impermeable surfaces which can lead to greater surface run-off.
Sewer Systems: Generally sewer systems create create artificial channels, which often reduces a rivers’ lag time and can lead to increased flooding downstream.
Pollution: Transport, industry and housing all create pollution which works its way into the water system. Areas that don’t have proper sewers and water treatment tend to be effected more. Metals and chemicals are particularly polluting.
Water table (groundwater depletion): Unsustainable use of groundwater can cause subsidence. Mexico City has experienced subsidence because of aquifer depletion underneath the city. On the scale, London has actually seen its water table rise since deindustrialisation has meant the demand for water has fallen.
Deforestation: Deforestation reduces interception and transpiration. Removal of trees can also increase the risk of mudslide by reducing slope stability and stops root uptake. Less interception speeds up the rate the ground become saturated and therefore increases the risk of flooding
Micro-climate: Urban areas create heat islands which can increase convectional rainfall. Particulates released by industry and transport also make excellent condensation nuclei.
Channelisation: Artificially smoothing channels may remove river discharge from one area, but areas down stream that haven’t been smoothed are likely to experience an increase risk of flooding.
Task:
Cut out the different strategies below and then sort them from ‘best to worst’. After this, discuss the criteria of what is best to worst. Create a spider diagram with the possible considerations or different objectives that might influence the ordering.
river_management_strategies card sort.docx
Managing the Rhine:
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| The Rhine has been manged for many years. This maps dates back to 1882. Source unknown. |
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| Click on the map to open the Interactive map of the Rhine |
Billions needed for flood protection in Switzerland:
An Alternative to Hard Flood Protection: Rhesi
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| geplant |
Describe two stream management strategies – one where you believe the costs outweigh the benefits and a second where the benefits outweigh the costs. [6 marks]
With reference to one named area of floodplain, evaluate the costs and benefits of at least three different stream management strategies. (10)