Rivers, flood and management CASE STUDIES
- Created by: selene98
- Created on: 08-04-15 20:35
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- RIVERS - CASE STUDIES
- Flooding
- South Asia flooding, 2007
- Facts
- Flood most years due to:
- Monsoon climate
- 90% of the land is low-lying
- Increased discharge from Brahmaputra river from molten snow and ice from Himalayas
- July+August 2007 - sever flooding especially in Bangladesh and India
- Flood most years due to:
- Factors
- Physical factors
- Heavy rainfall
- Sudden monsoon after dry and early summer
- Saturated soil and so increased runoff and discharge
- Peak discharge of Brahmaputra+Ganges coincided; greater discharge downstream
- Human factors
- Deforestation in Nepal + Himalayas
- less interception + increased discharge
- Growth of urban areas
- increased surface runoff
- Collapse of old dams
- Deforestation in Nepal + Himalayas
- Physical factors
- Impacts
- SOCIAL
- >2000 people died due to slow evacuation, drowning and reluctant to leave
- Lack of drinking water
- 25mil homeless
- Houses destroyed due to saturated porous rock
- Dhaka inundated
- 44 schools destroyed - loss of education
- ECONOMIC
- US$ 1bil damage to crops+property
- Loss of raw materials and livestock
- 10k km of roads destroyed
- ENVIRONMENTAL
- Polluted rivers
- Fertile silt deposited on floodplains
- SOCIAL
- Facts
- Carlisle flooding, Cumbria, 2005
- Facts
- Large drainage basin - high discharge
- Steep sides
- Short lag time due to many streams
- 8 Jan 2005, flooding of Carlisle by river Eden
- Factors
- Physical
- 36 hrs of heavy rainfall
- surface runoff on saturated ground
- 52 cumecs of peak discharge
- Human
- surface runoff from impermeable concrete
- Overflowed sewerage systems causing 25% of flooding problems
- Physical
- Impacts
- SOCIAL
- 3 people died and 3k homeless
- Loss on education
- problems with travel+ receiving post
- ECONOMIC
- £100mil in repairs
- 350 businesses shut down due to no electricity/transport/telephone
- Sewage, police station, council offices flooded
- 80 buses destroyed
- Roads and bridges damaged, e.g. Warwick Road
- ENVIRONMENTAL
- Increased river bank erosion is some areas
- Polluted rivers
- SOCIAL
- Facts
- South Asia flooding, 2007
- Flood management
- Hard engineering - Three Gorges Dam (China)
- Facts
- Yangtze River 6380km
- Rainy season (flooding) June-August
- Reservoir that stores 22km3 of water
- 26 turbines - largest hydroelectric power station in the world
- 3600km of levees on lower and middle part
- Positive effects
- Frequency of flooding reduced to every 100yrs
- The turbines produce 3% of China's electricity demand
- Safer to navigate the river
- Increase in river shipping (for bigger ships)
- Negative effects
- 13 cities submerged once reservoir is full
- Farmland and 657 factories will be flooded by reservoir
- Entrapment of sediment from the dam - severe flooding
- Endangered species + destroyed habitats, e.g. 100 baiji dolphins left
- The dam can increase flooding in tributaries
- Facts
- Soft engineering - Abingdon
- Facts
- Town in SE on Thams and Ock flood plains
- Houses have 1% flooding chance a year
- Hard engineering rejected due to costs and flood risk downstream
- Defences
- Gravel soakways on A34
- Flood storage area allowed to flood, e.g. Tilsley Park
- New houses on Ock flood plain to have better drainage systems
- Tesco to have permeable tarmac
- EA 24hrs Floodline
- Afforestation
- Flood wardens for warnings and advice
- Restrictions on land use
- Successfullness
- Many floods warnings by EA since 2008
- No flood on Ock floodplain but flood on Thames floodplain due to planning restrictions and land management
- 2008 flood: less damage, less cost, less injuries but flooding still occurs
- Facts
- Hard engineering - Three Gorges Dam (China)
- Flooding
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