Rivers, Floods and Management Case Studies

Rivers, Floods and Management Case Studies

1. Pakistan Floods July 2010

   • Unusually heavy monsoon rains
   • Indus River and Kabul River affected, causing a flood
   • Punjab, Khyber Puhktunkhwa and Capital territory worse affected
   • Causes
     • Low-lying country which is prone to flooding
     • Indus river flows through the Himalayas so has steep valley sides, therefore naturally has a higher discharge
     • Indus river has a higher drainage density as 3 other rivers join into it.
     • Most of Pakistan is effectively the floodplain for the River Indus, flat bottom valley
     • Floodplain not much higher than river level so when it floods it easily floods across the whole floodplain
     • Excessive, prolonged rainfall caused the saturation of soil and rocks so there will be less infiltration and more surface runoff.
     • No real strategy in place for when floods did happen
     • No restriction of land for settlement
   • Impacts
     • Social
       • 1.2 million people made homeless as homes destroyed or because they were fleeing
       • Emergency camps established
       • Agricultural resources were destroyed, causing shortages
       • Roads destroyed, some areas only accessible by helicopter, difficult to supply aid
       • A threat of social unrest
       • Increased threat of diseases
         • e.g. cholera, malaria, malnutrition
       • At least 1,600 people killed
       • Just before harvest
       • 5 million jobs lost
       • Unlikely to have insurance to cover losses
     • Economic
       • Villages wiped out
       • Extensive damage to roads, buildings and irrigation works
       • UN estimated rebuilding would cost billions of dollars
       • Factories might lose customers
       • Farmers loss of income due to harvest being destroyed
       • Scarcity of some resources resulted in the rise in price of commodities
       • Power lost for homes and businesses
     • Environmental
       • Areas of crops destroyed and it might not be possible to plant new crops
       • Contamination of water
       • Cattle Killed
       • Infrastructure destroyed
       • River Indus floodplain extended

2. Cumbria floods - November 2009

   • Affected Cockermouth and Workington
   • Causes
     • Upper course of river in mountainous areas
     • Focuses of the flood was the confluence where rivers joined together
     • Excessive, prolonged rainfall
     • Impermeable rock in the upper course of the drainage basin
     • Big floodplain
     • Flood had a high magnitude, so defences were not strong enough
   • Impacts
     • Long term
       • Education disruption
       • Travel disruption
       • Less food available
       • £100 million in insurance pay-outs
       • Insurance costs rise after
       • Decline in farming
       • Local businesses face months without income
       • Water supply contaminated
       • River channel changed shape and eroded quicker
     • Immediate
       • Schools closed down
       • Over 1300 flooded homes
       • Power supplies cut off
       • Access to emergency services difficult
       • 1 Death
       • Machinery damaged
       • Bridges collapsed and damaged
       • Livestock killed
       • Fields covered in sediment
       • Sewage came up from drains
       • Fences and walls destroyed

3. Hard Engineering Management

   • The Three Gorges Dam
     • 1.2 million had to be resettled as their homes were inundated
     • 1,200 historic sites inundated
     • £25 billion
     • Produces HEP for 13 million people
     • Reduces the flood risk for 15 million people
     • Improved water supply
     • Downstream sediment supply decreased by 50% - leading to increased erosion
     • Disruption to habitats and environment

4. Soft Engineering Management

   • Cheaper
   • Works with natural processes, more sustainable solutions to flooding
   • More sustainable