SEE: Water: 5.5B
- Created by: MaggieNaylor
- Created on: 16-03-22 17:19
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- 5.5B: Human actions exacerbating flood risk
- Changing land use
- Urbanisation in the 20th century meant many flood plains have been built on
- This leads to an increase in impermeable surfaces
- Leads to speeding up the drainage water to built-up areas
- Impedes channel flow due to building alongside rivers
- Agricultural development
- Deforestation, overgrazing, ploughing, drowning wetlands
- This usually occurs upstream, which then impacts downstream due to increased runoff and sediment
- 2015 TLD Flood
- Land use is prodominantly for sheep farming, leading to a loss of vegetation, causing faster runoff, reduced stream lag times, and high discharge peaks
- Deforestation, overgrazing, ploughing, drowning wetlands
- Urbanisation in the 20th century meant many flood plains have been built on
- Mismanagement of rivers using hard engineering systems
- Channelisation is the alteration of a river course to form straight channels
- This is meant to reduce flood risk, but usually just increases it further downstream
- This is because discharge is now increased overwhelmingly downstream
- This is meant to reduce flood risk, but usually just increases it further downstream
- Dams block the flow of sediment down a river, meaning a reservoir gradually fills with silt
- This means downstream there is increased river bed erosion, increasing flood risk because of increased discharge
- River embankments are designed to protect from floods
- However, they can fail when floods exceed their capacity
- When this happens the scale of flooding is much greater
- 2015 TLD Flood
- Hard engineering solutions used to raise river banks based on an incorrect flood return period
- River wall was 5m, but river rose to 5.9m
- Hard engineering solutions used to raise river banks based on an incorrect flood return period
- Channelisation is the alteration of a river course to form straight channels
- Changing land use
- -For the TLD, the environment agency says soft engineering is the best way to prep for flooding
- Reafforestation, restoration of meanders/channels/floodplains
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