ErosionErosion: the wearing away of the bed and banks of the riverchannel. There are four types of erosion that take place in ariver:1. Corrasion: the pebbles being transported wear away the bedand banks of the river channel.2. Attrition: The particles are knocked about as they aretransported, and they gradually become more rounded andreduced in size.4. Hydraulic Action: The sheer force of the water by itself canerode material from the bed and banks of the river channel.3. Corrosion (Solution): some rocks such as limestone are subject tochemical attack and slowly dissolve in the water.
TransportationTransportation: the river moves material as bedload (traction orsaltation), suspended load (suspension) or dissolved load (in solution).4. Traction: material rolled along the bed of the river.2. Suspension: very small and light material, usually fine clayand silt, are carried by the river.3. Saltation: material bounced along the bed of the river.1. Solution: some rocks such as limestone are subject tochemical attack and slowly dissolve in the water.
Diagram shows formation of a Meander show areas of erosion (red X’s)XXXXOutside InsideFast flowing water Slow flowingMore energy, so more erosion Less energy, so depositionWearing away of bank andbed – undercuttingMaterial deposited formingnew landRiver Cliff River BeachLateral erosion (sideways)
True or FalseA storm hydrograph shows how a rivers discharge responds following a periodof heavy rainfallRising Limb shows the increase in discharge on a hydrographThe shape of a hydrograph is determined by the speed in which flood watersare able to evaporate.•permeable rocks and soil have a high infiltration capacity and so will notabsorb waterOn a hydrograph, the flood is shown as a star above the base (normal) flow ofthe riverWhere more water is able to pass into the soil and travel to the river viathroughflow / groundwater flowRiver discharge does not respond immediately to rainfall inputs as only a little ofthe rainfall will fall directly into the channel.The fastest route to the river is via overland flow.The response of a river to a rainfall event can be measured in terms of thespeed of light