Physical and Human Causes of River Floods
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?- Created by: Phoebe
- Created on: 24-11-13 12:58
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- Causes of River Flooding
- Physical
- Drainage Density
- high drainage density means water reaches channel quickly
- speeds up transfer of water making flooding more likely
- high drainage density means water reaches channel quickly
- Long Profile
- steep upper course + flat lower course
- rapid transfer to low ground where water transfer slows
- build up of water might cause flooding
- rapid transfer to low ground where water transfer slows
- steep upper course + flat lower course
- Snow Melt
- form a store of water
- when melts store is rapidly released
- if ground is still frozen overland flow will occur and go into rivers quickly
- when melts store is rapidly released
- form a store of water
- Steep Slopes
- mountainous area rapid overland and through flow
- Rock Type
- Impermeable rock encourages overland flow
- rapid water transfer to river channel
- Impermeable rock encourages overland flow
- Intense/Prolonged Rainfall
- intense rain fall (e.g. tropical storms + monsoons) cause significant floods
- prolonged rainfall lead to river flood in early spring
- Drainage Density
- Human
- Agriculture
- arable farming
- areas left exposed
- lead to extra surface runoff
- areas left exposed
- arable farming
- Deforestation
- trees shelter the ground
- therefore removing trees means water can be transferred to channels quickly increasing risk of flood
- water that normally falls on leaves is then evaporated /stored temporarily
- therefore removing trees means water can be transferred to channels quickly increasing risk of flood
- trees also use water up fro the ground when they grow
- trees shelter the ground
- Flood Management + Warning System
- lack of appropriate flood defences and schemes or poor warning systems increase risk to people
- if flood defences are not repaired or upgraded floods are more likely
- badly maintained underground channels or bridges lead to blockages and flooding
- Building and construction
- building on floodplain creates an impermeable surface
- transfers water quickly to channel causing them to fill quickly and over flow
- building on floodplain creates an impermeable surface
- Agriculture
- Physical
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