Causes of Flooding - South Asia, 2007
Parts of south Asia flood most years due to:
- Monsoon Climate (80% of rain in 4 months)
- Low-lying land (e.g. in Bangladesh, 90% of land is less than 10m above sea level)
- Melting snow and ice from the Himalyas
- Monsoon after a very dry, early summer.
- Heavy and prolonged rainfall
- Peak discharges of two rivers (Ganges and Brahmaputra) coincided.
- Deforestation in Nepal and the Himalayas.
- Growth of urban areas (due to migration)
- Collapse of old earth dams.
Impacts of Flooding - South Asia, 2007
- 2,000 died (reluctance to evacuate, can't swim, poor transport links)
- Polluted wells caused 100,000 to catch water-borne diseases.
- 25 million homeless
- 112,000 houses destroyed in India (porous mud bricks became saturated).
- Dhaka (capital of Bangladesh) was inundated.
- 4,000 schools affected, 44 totally destroyed.
- US $1 billion.
- Factories closed (loss of raw materials) - many poor became unemployed.
- Loss of livestock (reliance on agriculture) + flooded fields caused low rice crop.
- Individual and national debt increased.
- Rivers polluted with sewage, but fertile silt deposited on flood plain.
Causes of Flooding - Carlisle, Cumbria, 2005
The River Eden reaches the sea near Carlisle and flooded due to:
- Large drainage basin
- Steep sided basin
- Many fast draining streams
- Heavy rainfall
- Rain fell on saturated ground
- High peak discharge
- Large built-up area with impermeable concrete and tarmac surfaces
- Little soil or vegetation
- Drains and sewerage systems overflowed in some areas
Impacts of Flooding - Carlisle, Cumbria, 2005
- 3 died
- 3000 made homeless for up to a year - temporary accommodation disrupted lives
- Personal possessions damaged
- 4 schools severely flooded
- Increase in stress-related illness
- £100 billion
- 350 businesses shut down
- 'United Biscuits' - 33/1100 employees lost their jobs
- 70,000 addresses lost power
- 80 buses destroyed and many roads and bridges damaged
- Increased river bank erosion
- Rivers polluted with rubbish and sewage
Flood Management Strategies - Yangtze River
Hard Engineering Strategies:
- Many dams, including Three Gorges Dam - reservoir catches water and slowly releases it, largest HEP station in the world
- Many levees
- Reduced major flooding from 1 in 10 years to 1 in 100 years
- Produces a lot of electricity (3% of China's demand)
- Safer to navigate up the river - increase in river shipping
- People have had to relocate (2 million)
- Reservoir will flood farmland, factories etc.
- If dam fails, catastrophic flooding could occur
- Destroys habitats and endangers species
- Doesn't protect everyone - increased risk of flooding elsewhere
Flood Management Strategies - Abingdon
Soft Engineering Strategies:
- Gravel soakways
- Low value land allowed to flood
- Planning/Land-use restrictions
- Local Flood Warning Plan - 25 Hour Floodline
- Internet advice
- Voluntary flood wardens
Damage is reduced - Floods still happen:
- Difficult to measure success
- Flood warnings were issued in 2008
- Ock flood plain wan't flooded, but the Thames flood plain was
- The 2008 floods did less damage than in previous years (no lives lost)
Issues in Cold Environments - The Antarctic
- Wilderness area - unaffected by large-scale human activity
- Contains 90% of all ice on Earth
- Ice sheet covers most of Antarctica all year round
- Little available water for plants to grow
- Very cold - Average of -49 degrees C + very little sunshine
- Very few plants and animals can survive there - there is abundant bird/sea life
- Takes a long time to recover from any damage
- Sea ecosystem is also fragile (food chain easily affected by one species)
- 300 species of fish, 8 species of whale
- Attractive scenery
- Large underground deposits of coal and iron ore, large oil reserves
Antarctica Case Study - Antarctic Treaty
- Set up in 1961 - 12 countries came up with laws to protect it
- Includes many protocols and conventions that control or prohibit certain activities
Oil Extraction, Mining and Whaling:
- Oil extraction and mining are currently banned
- 'Madrid Protocol' of 1998 - ban is in force for 50 years (may be lifted in 2048)
- In 1994 the Antarctic was declared a whale sanctuary and commercial hunting was prohibited (some allowed for scientific research)
- In 2007-2008, 46,000 tourists visited the area
- 5,000 scientific researchers there in the summer, 1,000 in the winter - 'Protocol on Environmental Protection' - scientists must remove waste etc.
- 'Convention for the Conservation of Antarctic Marine Living Resources' - quotas on fish catches (e.g. krill)