Case studies for rivers

Mozambique
1. Causes
  1. 3 days of heavy rain in January
  2. 5 weeks of continuous rain
  3. Cyclone Eline 22nd Feb
  4. Less grassland so less infiltration
  5. No flood area - being used for farming
  6. Urabanisation
    1. Causes water to flood in upper courses of river
2. Effects
  1. More than 1 mill homeless
  2. Thousands drowned
  3. Quick spread diseases in refugee camps
  4. Destroyed farmlands
    1. 83% pop work in agriculture
  5. Repair costs
    1. $30mill roads
    2. $6mill railways
    3. $4mill electric supplies
3. Flood defences
  1. Can't afford
  2. Able to start flood warnings due to funding from EU
  3. Can't control river as upper courses in other countries
Sheffield
1. Causes
  1. 1 months rain fell in one day on June 15th 2007
    1. Soil saturation
      1. The 10cm ran into lakes and rivers and surface runoff
  2. 10cm fell on 25th June
  3. The confluence of several rivers
    1. 2 rivers joined and one was already full - water backed up
      1. Banks overflow causing flooding
  4. Sheffield in a valley = surface run off
    1. Reservoirs filled up and flooded
2. Effects
  1. Flooded football stadium - 8 metres deep
    1. Cost several mill to remove water
  2. 43% houses flooded - 9 months to sort out
  3. People had temporary housing in caravans
  4. Sewage escaped into drinking water
    1. Health risks
  5. Dangerous situations - evacuated
  6. 400 people slept overnight in offices
  7. 23 airlifted to safety
  8. Tool making company had repair costs of £15mill
  9. Shopping centre badly flooded and stock lost
Preventing flooding in River Derwent - North Yorkshire
1. Soft engineering
  1. Washlands between embankments and river
  2. Building restricted on floodplain
  3. Planting in catchment
  4. Reinforcing banks with woven willow to stop bank erosion and so the river doesn't get silted up
  5. Warning systems
    1. Data on rainfall
2. Hard engineering
  1. Embankments
    1. Didn't prevent flood damage in 1999
  2. Sluice gates upstream hold back water and let it out steadily
  3. Rural area and high value land - hard engineering isn't appropriate for the whole area
The Sahel - desertification
1. Causes
  1. Overgrazing
  2. Farming of average land
  3. Destruction of plants in dry regions
  4. Normally rains 1-2 months a year
    1. Rainfall been below average since 1970 - some years 25% less
    2. When it does rain - surface runoff
2. Effects
  1.  Other years there is no rain at all  rivers dry up  water table falls  farmers crops fail  animals die  desertification  decreased food supplies  famine
  2. Soil becomes less usable
  3. Lack/damage of vegetation
  4. Famine
  5. Food loss
  6. People near affected area
Colorado dam
1. Regulates river flow
  1. Costs
    1. Less energy left to move sediments
      1. Which keeps water warm for fish
  2. Benefits
    1. Less flood risks - flood peaks smoothed out
2. Creating resevoirs
  1. Costs
    1. Loss of land flooded by reservoir
  2. Benefits
    1. Regular all-year water supplied for cities like Las Vegas
3. Trap sediment behind dam
  1. Costs
    1. Shrinking sandbanks means some animals lose habitat and tourists lose rafting
  2. Benefits
    1. /
4. What?
  1. Hoover dam
    1. 726 feet tall
  2. Fought over by urban dwellers, farmers and Mexicans - all need its water
    1. Native Americans not happy - will ruin scenery and disturb settlements
Water stress
1. Lake Chad
  1. One of largest lakes in world
  2. Supports over 20mill people
  3. Global warming is evaporating lake
  4. Lack of rain
  5. People need lake for fishing, drinking and farming
2. South East England
  1. Dry winters so reservoirs didn't fill up
  2. Last Jan only 2/3 of annual monthly rainfall
  3. Hose pipe bans
  4. High pop and low precipitation
  5. 2011 farmers lost out on crops
    1. One farmer lost £20,000 due to spring drought
  6. In 30 years there will be bad drought if nothing is done
3. Sonoran desert
  1. Uses of water
    1. Supply pop demand
    2. Water features
    3. Farms
  2. Why rate is increasing
    1. Pop increasing 1.8 - 3.6 mill
    2. Urbanisation
  3. Impact
    1. Water supply not sustainable
    2. Water quality deteriorating
    3. Expensive
    4. Water table falling 3m in ayear
      1. Ground giving way
    5. Building canals-destroying habitat
4. Australia
Dhaka, Bangladesh
1. slum on disused railway station. No safe water or toilets
2.  WaterAid constructed 6 tube wells and 2 new sanitation blocks
  1. people are no longer continually ill
  2. they can run facilities themselves
  3. moving out of poverty

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Case studies for rivers

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	Created by Anna Hollywood about 11 years ago