Bostcastle Floods 2004

Information on Bostcastle floods

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  • Created by: Daniel
  • Created on: 17-05-12 12:05

Where and when?

  • Bostcastle - small town on north coast of Cornwall (30km NW of Plymouth)
  • Crackington Haven
  • Monday 16th August 2004
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What happened?

  • Flash flood as result of short periods of heavy rainfall
  • River levels rose with very little warning, reaching a peak within minutes or hours
  • Very destructive and can cause loss of life
  • 12:30 - Heavy rain began to fall
  • 12:39 - Flood warning issued
  • 17:00 - Floods reach peak, cars swept away
  • 17:10 - Major incident declared
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What was the impact?

  • Up to 1,000 people had to be evacuated from their homes
  • 20 accomodation providers forced to shut down (Bostcastle's economy is 90% reliant on tourism)
  • 58 properties were flooded, 4 demolished
  • 4 footbridges along Vallency Valley washed away
  • 84 wrecked cars
  • Roads blocked by flood water
  • £2 million in damage - no fatalities
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What were the causes? (Heavy rain)

  • 1. Heavy rain falls on waterlogged ground
  • 2. Rainfall unable to soak in, so runs into river
  • 3. River rises dramatically, bursting its flood valley floor
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What were the causes? (Steep-sided valleys)

The steep sided valleys that converge down to the sea, known in the trade as “flashy catchments”, act as huge funnels and can produce true flash floods after a sudden cloudburst or prolonged heavy rainfall

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What were the causes? (Slatey impermeable rocks wi

The cause was the combination of

           intense convectional rain,

           local topography and

           the geology

      resulting in a flash flood

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How is the impact of future floods being reduced?

  • Control/restrict developments on flood plains
  • Build bigger culverts on both rivers
  • Build embankments and strengthen natural levees
  • Afforestation (plant more trees)
  • Flood control Dam (hold back rainwater and release it slowly)
  • Dredge and strengthen/straighten river channels
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