Rivers Case Studies

Rivers Case Studies

1. Boscastle

   • Facts and Figures
     • 184mm rainfall 24hrs
     • 16th August 2004
     • 2 million tonnes of water flowing through water in Boscastle that day
     • 1 in 400 chance
     • Two large tributaries- River Jordan and river Valency
   • Causes
     • Physical
       • Weather and climate: Depression formed over the Atlantic shortly before flood, remain of hurricane Alex-slowed down on land making rain intense. Trough at the top of boscastle.
       • Winds: Convergence of the prevailing SW winds and depression path causes vertical uplift of air=cumulonimbus clouds and more rainfall
       • Topography: Boscastle bottom of steep hill, funnel=overland flow and surface run off
     • Human
       • Land use: Upper part of village urbanisation and hedges removed to make fields bigger
       • Lack of flood control: No raised banks or emergency drain ditches
       • The sewer and drainage systems: Old sewage systems, small capacity but were over ran
   • Impacts
     • Social
       • 58 homes flooded
       • No deaths
       • 32 cars swept away
       • Sewer pipes contaminated clean water supplies
       • 4 footbridges along Valency washed away
       • Long term disruption and stress/anxiety to people
     • Economic
       • Damage = Re-builds 2 million
       • Rescue operation including helicopters, police, fire service
       • Loss of tourism, major loss of income
     • Envrionmental
       • Costal wildlife and habitats
       • Costal pollution as debris from cars and buildings flowing into the sea
   • Management
     • Hard Engineering
     • £4.6 million defence were used and breeched
     • River Valency widened and lowered from the bridge
     • Height of the car park has been raised using stones removed from the river bed
     • Plans to demolish lower bridge near harbour and put a new larger bridge higher up the river
     • Helicopter services on rescue mission for people stuck in homes

2. Bangladesh

   • Facts and Figures
     • 2004
     • Low lying
     • Edge of Ganges delta
     • 2004 Monsoon season was a bad season
   • Causes
     • Physical
       • Sources of all major rivers in Himalayas, adding substantial discharge through snow melt during spring
       • Asia, monsoon climate and wet season between May and September=low pressure and winds bringing heavy rain
       • Bangladesh suffers from cyclones, high winds, heavy rain and storm surge
     • Human
       • Rapid deforestation in Himalayas, less interception
       • Urbanisation: Capital city Dhaka, pop 1 million
       • Poor river management
       • Population replies on agriculture to survive- rice growth on rented plots of land meaning they pay little tax relying heavily on foreign aid
   • Impacts
     • Social
       • 36 million deaths
       • 800 death toll
       • Farmers in rural areas cannot go out and sell crops
     • Economic
       • Damage to infrastructure (Roads, Bridges, buildings, irrigation)
       • All flights suspended in July
       • Damage $2.2bn
     • Environmental
       • July to August, 38% land flooded -800ha of agricultural land
       • Floods caused river bank erosion
       • Animal homes damaged and destroyed
   • Management
     • Short term
       • Government and Non government organisations provide emergency relief: Rice, Clothing, Medicines, Blankets and Towels
       • July, United Nations; Supplied a distaster management team to supply critical emergency supplies and conducted a 'damage and needs assessment' in effected areas
       • Bilateral aid from individual countries directed by UN
       • Self help schemes: local people re-build project
     • Long Term
       • Foreign aid
       • Recent small scale community based project- Early warnings and food shelters successfully put in place=lives saved
       • Following 2004, additional funding was granted for 5 year period. Loan from world bank to pay for repairs, water resources, management and education