River Case Studies
- Created by: ManicGiraffe
- Created on: 12-05-16 13:48
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- Case Studies- Rivers
- Flooding of South Asia, 2007
- Factors
- Physical
- Monsoon, suddenly after very dry early summer
- Heavy rainfall- Assam 169.5 mm in 24 hours n 22nd July
- Long duration of heavy rainfall completely saturated soil, increasing runoff
- Human
- Deforestation in Nepal and the Himalayas, less rainfall intercepted
- Growth of urban areas, due to migration
- Collapse of earth dams in India causing further flooding
- No flood defences or warning system (poor country)
- Low incomes so little money to recover after the flood
- Physical
- Impacts
- Social Impacts
- Over 2000 people died, as people where reluctant to evacuate
- Lack of clean drinking water, wells were polluted
- 25 million made homeless
- 112000 houses destroyed, porous mud bricks saturated
- Children lost out of education 44 schools destroyed
- Economic Impacts
- Estimated $billion, damage to crops and property
- Factories closed around Dhaka. Many poorest workers became unemployed
- Loss of livestock, 80% of Bangladesh rely on agriculture for livelihood
- Debt increased individually and nationally
- 10,000 km of roads destroyed
- Environmental Impacts
- Flood deposited fertile silt on flood plain
- Rivers polluted with sewage
- Social Impacts
- Factors
- Flooding of Carlisle, Cumbria 2005
- Factors
- Physical
- Heavy rainfall on 6th January 36 hours, 200 mm rainfall
- Rainfall on already saturated ground
- Human
- Large built-up area, lots of tarmac so little infiltration
- Drains and sewage system overflowed becoming a source of flooding in some areas
- Physical
- Impacts
- Social Impacts
- 3 died
- 3000 made homeless
- Children missed out on education, 4 schools serverely flooded
- Increase in stressed related conditions after the floods
- Economic Impacts
- Year to repair damage, over £100 million in damage
- 350 businesses shut down- no electricity, telephone service or transport
- 70,000 addresses no power
- 80 buses destroyed, as well as roads and bridgges
- Environmental Impacts
- Flooding increased river bank ersoion
- Rivers were polluted with rubbish and sewage
- Social Impacts
- Factors
- Hard Engineering, Yangtze
- Runs through China, 6380 km long
- Seasonal flooding common- has rainy seasons June-August
- 5 major floods over last 100 years
- Defences- 3 Gorges Dam
- Multiple dams on the Yangtze to reduce flooding- biggest is 3 Gorges Dam
- 101 km high, work began in1994
- Reservoir built up behind the dam to catch flood water can store 22 km3
- Largest hydroelectric power station in world
- Effects
- Positive
- Major flooding reduced from every 10 years to every 100 years
- 3% of China's energy provided by hydroelectric on dam
- Safer to navigate the Yangtze, river shipping increased as bigger ships can travel up it as reservoir is deeper
- Negative
- People had to relocate, as water level in reservoir risen
- Reservoir flooded farmland, over 600 factories and 1300 sites of cultural intrest
- Sediment usually carried by the river getting trapped by the dam causing it to fail
- Dam could destroy habitats
- Dam doesn't protect everyone- increased flooding of tributaries leading to the dam
- Positive
- Runs through China, 6380 km long
- Soft Engineering, Abingdon
- Defences
- Gravel soakaways on the A34 road
- Low-value lands allowed to flood
- Planning restrictions on new housing development built on Ock flood plain
- Tesco's forced to revise extension plans, had to add drainage improvements
- Flood warning plans and 24 hour floodline
- Local voluntary flood wardens- advice/ warnings
- Restrictions on land use
- Reduces damage, but floods still occur
- Difficult to measure success of defences- as less flooding could be less serve weather or successful defences
- Several warnings issued by Environment Agency, 2008
- 2008 floods made less damage
- Defences
- Flooding of South Asia, 2007
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