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Human response to flood
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Human response to flood



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  • 1. Floodmanagement
  • 2. IMMEDIATE LONG TERM Provide boats to rescue  Prediction people  Hydrograph analysis Supply medicines to treat  Real-time monitoring and prevent spread of  Studying past records diseases Supply clean water  Hard Engineering Distribute food and  Soft Engineering temporary housing (tents) Aids from foreign countries
  • 3. a. Hydrograph Analysis: - analysing a series of storm hydrographs for a basin, it is possible to device estimates for the behavior of the river for storms of different sizesb. Real time monitoring: 1. A series of monitoring stations are set up along the rivers 2. Automatic measurements are sent to a central flood control office 3. allows hydrologist to follow the progress of flood waves down rivers 4. It is expensive and difficult to set up esp in remote areasc. Studying past records: 1. Enables people to workout the likelihood of floods of different sizes
  • 4.  Involve in trying to lengthen the amount of time it takes for water to reach the river channel  increasing the lag time Flood management techniques:  Hard Engineering options  Soft Engineering options
  • 5. HardEngineering • More expensive • Have greater impact on the river and the Options surrounding landscape SoftEngineering Options • More ecologically sensitive
  • 6. Hard Engineering Soft Engineering options options• Dam Construction • Afforestation• River Engineering: • Ecological Flooding realignment / Channelisation • Planning• Revetment, e.g River Yangtze, China • Flood warnings• (Refer pg 61-62 of yr booklet) • Public relief / Emergency action
  • 7. HARD ENGINEERING SOFT ENGINEERING Dam Construction  Afforestation River Engineering: realignment /  Ecological Flooding Channelisation  Planning Revetment, e.g River Yangtze,  Flood warnings China (Refer pg 61-62 of yr  Public relief / booklet Emergency act
  • 8. • Store and control river dischargeDams • Used to control tributaries of the Mississippi , e.g River MissouriLevees & • By raising the height of river banks, water can be containedretaining • Flood walls in York (Nov 2000) contained record levels and saved many homes from flooding walls • Increase the speed of flow and reduces the length of theStraightening river meanders • (R. Mississippi has been shortened by over 24km) Flood • Provides additional channels alongside existing course of river relief • Maidenhead, Windsor and Eton relief Channel removed 5500 homes from the threat of Thames floodwaterchannels
  • 9. River revetment
  • 10. • Increase interceptionAfforestation • Reduces run-off • E.G Tennessee river valley, a tributary of R. Mississippi • Floodplain zoning Planning • Allows certain areas to flood naturally regulations • Land uses are limited to grazing and recreation Contourploughing in • Reduce the amount of surface run-off Semi-arid • Reduce the liabilty to flooding area
  • 11. • Protect the natural river channel & valleyWetland and riverbank • Maintained habitat and species diversityconservation schemes • Arable land is returned to its former use as natural meadowland • In times of high discharge sluice gates are opened and water Is allowed to flood adjacent areasWashlands or Spillways • A new washland in Yorkshire saved many homes in Dorncaster from flooding in 2007Forecasting • In Bangladesh, the yearly floods which engulf most of the floods and countryside cannot be prevented, but people are given warnings enough warning they can take refuge in flood shelters
  • 12.  Largest hard-engineering project ever undertaken on a river When: 2009 Location: Yangtze River 3 gorges:  Qutang gorge  Wu Gorge  Xiling Gorge
  • 13.  Generate up to 22 500MW of power, reducing the country’s dependence on coal Largest power station in the world Supply Shanghai’s 13 million people with water Protect 10 million people from flooding Water level will be raised to allow shipping above the Three Gorges (formerly rapids)
  • 14.  Most floods in recent years have come from rivers that join the Yangtze below the Three Gorges Dam The region is seismologically active and landslides are frequent Silting as a result of increased deposition and the development of a delta at the head of the lake. Up to 1.2 million people have to be moved to make way for the dam
  • 15.  Much of the land available for resettlement is over 800m above sea-level, cold & infertile soils on steep slopes Dozens of towns will be flooded e.g. Wanxian & Fuling Dam will interfere aquatic life – the white flag dolphin is threatened with extinction Archaelogical treasures wil be drowned, including the Zhang Fei Temple
  • 16. White flag Dolphin
  • 17. Zhang Fei Temple
  • 18.  Intense tropical rains  bring floods in the Komadugu-Yobe river basin Between June and August Traditional farming focuses on the renewal of fertile silt deposits with the floodwaters
  • 19. Approach: Conserves the value of wetlands both economically and environmentally Promotes sustainable development in the area for people and wildlife Teaches local people about wetland management Release large wet-season flows from Tiga and Chawalla dams into rivers
  • 20.  Water and alluvium are distributed more fairly Supports the traditional method of irrigation and farming Marsh grazing land is maintained Involves programme to monitor:  The extent of flooding and the changes in vegetation and wildlife  The use of water from village wells in order to check levels of the water table  Competition for land between animal herders and crop farmers Distribution of fuel-efficient wood stoves was design to reduce wood consumption people to resolve conflicts