Unit 2 geography rivers 2

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Human factors that help to cause flooding
Buildings - Concrete is impermeable, water flows faster, drains lead water to river help to make it over flow
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Chopped down forest - no trees/plants to get in the way or absorb water, so effects surface runoff.
Drain - directs water to river, speeds up the flooding effects.
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Physical factors effecting flooding
Water logged pitch - water has no where to go if cracks/ air gaps in soil all filled up causing surface runoff.
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Steep hill - gravity causes the water to travel faster making it harder to stop.
Rain - Heavy rainfall fills up the rivers making them more likely to flood, effects runoff + ground water flow
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Boscastle floods - north cornwall 2004- 125mm rainfall in a few hours, saturated ground, steep slopes
Houses damaged, destroyed, people's holiday places/ caravans destroyed/shut down. Causing lack of tourism to area, shops destroyed, no income, insurance higher, cras/caravans swept to sea - could harm fish.
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Over 5 million properties in the UK are at risk of flooding, to save us we have prediction, prevention, planning, forecasting.
Properties can: Have concrete floors instead of wooden so no rotting, move electric sockets higher, lightweight doors that can be moved upstairs if necessary, put buildings on stilts.
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Channelisation- river channel widened or deepened so it can carry more water or straightened, long lasting, effectively protects immediate area, altering river channel may lead to greater risk of flooding downstream, unnatural & visually intrusive
Dams - giant concrete wall put against a river controlling the amount of discharge. Can be used to produce hydroelectric power + recreation purposes. Very expensive, sediment dropped so more erosion downstream, can flood settlements & agriculture.
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Floodplain zoning - authorities introduce policies to control urban development close to or on the floodplain. Cheap, sustainable. Doesnt help with housing shortages, harder to enforce planning regulations in LICs
Afforestation - Trees planted in catchment area of river to intercept rainfall and slow flow of river. Relatively cheap, improves quality of envinmnt, soil erosion avoided, very sustainable. Often conifers - makes the soil acidic.
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Flood walls - vertical barrier usually made from concrete, can be used in areas where space is limited, easily + quickly erected in pre constructed sections. Must be assembled well otherwise water can get through joints.
Storage areas - A large depression close to the river that will fill with water if the river overflows, natural looking, doesnt damage environment. Need large area of unused land.
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The river Nene, Northampton - In 2002 a 450m clay flood embankment was built upstream creating a flood storage area behind it, it cost £2 million.
In 2003, warning system was upgraded so now aim to give 2 hours notice of possible onset of flooding. 4m high flood walls been installed protecting housing + industry.
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Other cards in this set

Card 2

Front

Drain - directs water to river, speeds up the flooding effects.

Back

Chopped down forest - no trees/plants to get in the way or absorb water, so effects surface runoff.

Card 3

Front

Water logged pitch - water has no where to go if cracks/ air gaps in soil all filled up causing surface runoff.

Back

Preview of the back of card 3

Card 4

Front

Rain - Heavy rainfall fills up the rivers making them more likely to flood, effects runoff + ground water flow

Back

Preview of the back of card 4

Card 5

Front

Houses damaged, destroyed, people's holiday places/ caravans destroyed/shut down. Causing lack of tourism to area, shops destroyed, no income, insurance higher, cras/caravans swept to sea - could harm fish.

Back

Preview of the back of card 5
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