Geography - Rivers

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define hydraulic action in rivers
pressure of water being pushed against the banks and beds of the river
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define corrasion in rivers
particles carried along the river thrown against river banks with considerable force
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define attrition in rivers
wearing away of rocks in a river as they roll and knock each other, chip away until smooth pebbles or sands formed
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define solution in rivers
chemical reaction between certain rock types and river water eg- limestone
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what is located in the upper course of a river
v shaped valley, interlocking spurs and waterfall
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describe the formation of a waterfall
softer rock sat underneath hard rock (basalt+sandstone), soft rock eroded by hydraulic action creates a plunge pool. hard rock left as overhang, pulled down by gravity and soft rock keeps getting eroded. Waterfall retreats causing a gauge
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whats located in the middle course
meander
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describe formation of a meander
outside bend is undercut(eroded laterally), inside bend materials deposited(most friction), horseshoe formed, becomes tighter, ends join cutting of loop
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whats located in lower course
ox bow lake, floodplains and levees
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formation of an oxbow lake
continual erosion, meander bend moves closer then meets. when flooding occurs river cuts through gap leaving a straight channel, river cut of from meander creating oxbow lake
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formation of floodplains and levees
rivers flooded, leaks onto floodplain, river drops material close to river channel. builds up and levees form of alluvium silt
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human factors causing flooding
vegetation removed meaning less interception, ploughing up+down instead of around channels, dams might burst therefore excess water
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physical factors causing flooding
hot dry weather makes soil hard so can't soak up rain, steep valley slopes makes rain runoff rapidly, river beds which are silted up make channels smaller
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list two effects of flooding on people and the environment
USA 2006 and Bolivia 2007
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What happened in USA 2006 flood
NYC, Jersey+Pennsylvania states evacuated (200,000 people), rising water in Susquehanna river, 2 truck drivers died on interstate 88 Sidney NYC, one motorist died swerved to avoid waged out road, Holmesville NYC
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What happened in Bolivia 2007 flood
river burst their banks, 19 people died due to Rio Grande, tributary in Amazon. 340,000 people effected, 100,000 left homeless, roads worst hit= Santa Cruz+Beri as blocked by mudslides
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What does the Met office do
predicts likelihood of river flooding
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What does the Environment Agency do
provides info on flooding risks using warning signs
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what does DEFRA do
responsibility for deciding locations the need to be defended and provides money
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How are houses built when in risk of flooding
stilts, plug sockets moved up the wall, waterproof paint, concrete floors, expensive furniture moved upstairs
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list three soft engineering techniques
afforestation, warning systems and wash land
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list three hard engineering techniques
channelisation, flood walls and embankments
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advantages and disadvantages of channelisation
long lasting, effectively protect immediate area however unnatural and visually intrusive
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advantages and disadvantages of flood walls
used in areas of limited space but have to be assembled very well so no water gets through cracks
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advantages and disadvantages of embankments
can be used as path along river, earth embankments provide habitats however concrete embankments spoil view and banks often not made high enough
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advantages and disadvantages of afforestation
cheap, sustainable, improves environment however increases risk of a fire and can spoil natural look of the landscape
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advantages and disadvantages of warning systems
cheap, electronic communication is fast however people might not have enough time to prepare
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advantage snd disadvantages of wash land
cost effective as nothings built, potential wetland site for birds and plants, however large land areas are taken over and cant be built on
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Other cards in this set

Card 2

Front

define corrasion in rivers

Back

particles carried along the river thrown against river banks with considerable force

Card 3

Front

define attrition in rivers

Back

Preview of the front of card 3

Card 4

Front

define solution in rivers

Back

Preview of the front of card 4

Card 5

Front

what is located in the upper course of a river

Back

Preview of the front of card 5
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