AS Geography: Flooding Case Studies

Flooding case studies for Geography AS Level


Bostcastle, Cornwall, 2004

  • 16th August 2004
  • By midday thundery downpours developed in Southwest England as a result of an intensive low-pressure weather
  • 200mm of Rain fell in 24 hours
  • Most of this fell between midday and 5pm
  • Rainfall most intense between 3pm-4pm (when it exceeded 100mm h)
  • Rainfall was very loacalised
  • Rainfall heaviest toward east of Boscastle on high ground.
  • The high land encouraged precipitation in the form of orographic rainfall
  • Ground was already saturated due to previous wet weather which reduced further infiltration into the ground
  • Village of Boscastle lies in a deep valley-downstream of the confluence of the rivers Valency and Jordan
  • Runoff to the river was rapid
  • Flooding first reported at 4pm
  • 60 or so properties submerged-not all these in the town, some within the tributaries  catchment area
  • 70-80 cars swept away
  • Damage to roads, bridges, property and services-no deaths
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Southern Britain, July 2007

  • Weather conditions throughout summer of 2007 were exceptional
  • Total rainfall (May-July_)was the highest on record for England & Wales since 1766
  • 20th July-was exceptional rainfall
  • Outstanding storm totals were reported across much of southern Britain
  • 144mm Pershore, 111 mm at Chieveley, 120mm at Brize Norton 
  • Historical Data suggests such a flood only occurs once every 100 years
  • Summer usually reduces risk of flooding with dry soil, however early summer rainfall meant that the soils were already close to saturation
  • Groundwater levels also much higher than usual
  • Intense storms lead to a number of loacalised but severe flash floods in Urban areas (Stratford-upon-Avon and Leamington Spa in Warwickshire, Ludlow in Shropshire and Buckingham)
  • The rainfall quickly overwhelmed urban drainage systems
  • Emergency services were widely deployed to rescue stranded people and organise evacuations
  • Transport disrupted, last day of school-therefore a lot of holiday traffic
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Southern Britain, July 2007

  • Thousands stranded on the M5 for hours
  • As the floods moved downstream many floodplains were inundated, causing serious flooding and extreme crop damage
  • Worst affected areas in the lower part of the Severn and Warwickshire Avon basins (Gloucester, Cheltenham and Tewkesbury) and some upper reaches of the Thames catchment, including Oxford.
  • 3 people died-in Gloucestershire
  • 45,000 homes without power
  • 350,000 homes without running water, 140,000 still affected more than a week later
  • £25 million damage to Gloucestershire's roads
  • Farmers lost up to 50% of crops leading to shortages and raised prices the following Autumn
  • £3 billion flood damage covered by insurance
  • £1 billion cost to the water industry
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Bangladesh, 2004-1

  • Bangladesh-Low lying country most of which lies on the delta land of three major rivers Ganges Brahmaputra and Meghna-The sources of these rivers is in the Himalayas, so snow melt adds to their discharge during spring
  • Experiences a wet season between may and September with low pressure and winds blowing from Southwest bringing heavy rain to the coast
  • During the rainy season Bangladesh suffers from cyclones than bring, winds, precipitation and storm.  These conditions increase the discharge of the rivers and their distributaries-causing regular floods
  • Urbanisation has added to the role of the severity of the floods
  • Dhaka now has a population of more than 1 million
  • Rapid Deforestation in the Himalayas has had a negative effect on the rate of interception and evapotranspiration-resulting in more water reaching the rivers
  • River management hard in LEDC's like Bangladesh (one of the poorest countries in the word) with a gross domestic product per capita standing at around $300.
  • Most of the population rely on subsistence farming, growing rice on rented plots of land
  • Bangladesh relies heavily on foreign aid to finance large development projects which might help prevent floods
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Bangladesh, 2004-2

  • In 2004, the monsoon season brought more rainfall than usual.
  • Later June through to September three main rivers burst there banks
  • During July, August around 38% of the total land area of the country was flooded, including 8000,000 hectares of agricultural land and the capital city, Dhaka.
  • 36 million out of a 125 million were made homeless
  • By Mid-september the death toll had risen to 800.  Many people died due to lack of clean water
  • Flood also caused serious damage to the country's infrastructures, roads, bridges, embankments, railways, irrigation systems.
  • Value of the damage was assessed as being $2.2 billion, 4% of the GDP for 2004
  • In July, the UN activated a disaster management team to coordinate the activities of various UN agencies-who supplied critical supplies.
  • People in Bangladesh are resilient, so self-help schemes were common
  • In poor countries like bangladesh long term responses relies on other countries
  • Following the 2004 floods, finical aid was granted for 5 years from a loan from the world bank
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Hard Engineering-Three Gorges dam, China

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Nice River Quaggy slide :)



Helpful and consise - Thanks :)

lyle calnan



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