Rivers, Floods and Management 3

Rivers, Floods and Management 3

1. Quaggy Restoration Scheme

   • new water park was made to collect water
     • used as a wetland
     • Collects 3 olympic swimming pools worth
   • Reduced to the river being more natural
   • Reduced risk of flooding for 600 houses

2. Impacts of Flooding

   • People and animals killed
   • Contaminated water from sewage
   • Properties damaged
   • Business shutdown
   • Public transport and roads destroyed
   • Crops destroyed
   • River Sediment deposited on floodplain
   • Wetlands created

3. Bangladesh Flood 2007

   • Causes
     • Monsoon season came early
     • 169mm of rainfall in 24 hours
     • Long duration of rainfall
     • Deforestation in Nepal meant more discharge
     • Growth of urban areas meant more surface runoff
   • Impacts
     • Long Term
       • 44 Schools destroyed so education lost permanently
       • 550000 hectares could not be used again due to fertility
       • Unemployment because factories had to repay damage
     • Short Term
       • 2000 people died
       • 110000 people lost houses
       • 25 million made homeless
       • Livestock were lost

4. Flood Management strategies

   • Hard Engineering
     • Dams
       • Large walls built across a river. forms a reservoir behind it. often use turbines to produce electricity. provides job opportunities. Are very expensive. affect habitats for humans and animals
     • Channel Straightening
       • Meanders are removed, meaning water flows down faster. often causes more issues down stream is water occurs there quicker. also disturbs wildlife habitats
     • Levees
       • Raised embankments, allows more water to be held. Quite expensive and if breached severe flooding could happen
   • Soft Engineering
     • River Restoration
       • Making the river more natural. little maintenance is needed, local flood risk can be increased but habitats are created.
     • Urban Surface alternation
       • Building porous pavements. water can infiltrate easier so discharge decreases. EXPENSIVE!!
     • Land use Management
       • Planning restrictions to prevent building from being in floodplain areas. also reduces infiltration but it restricts development

5. Carlisle Flood 2005

   • Causes
     • Heavy rainfall
     • Large Built up area so surface runoff is very high
     • Drains and sewage systems overflowed in some areas
   • Impacts
     • Short Term
       • 3 people died
       • over 3000 people made homeless
       • 350 businesses had to shutdown
     • Long Term
       • took over a year to repair at 100million
       • 4 schools severely flooded, people lost out on education
       • Stress related illnesses increased

6. Three Gorges Dam

   • Positive Effects
     • Reduced major flooding from once every ten years to once every 100
     • Provides 3% of Chinas demand for electricity
     • Safer to navigate shipping through
   • Negative Effects
     • 1.3 million people had to relocate people
     • Dam will trap sediment and then causes catastrophic effect
     • Reduced food supply for animals in river
   • 1958 flood, causes 33000 people to die and 18 million people had to move