Case Study 1 - Flash Flood - Boscastle

Case Study 1 - Flash Flood - Boscastle

1. Location

   • Is in Cornwall
     • Located in the South-West of England
     • On the North Cornish Coast
     • North-West of Plymouth
     • North-East of Newquay

2. Timeline of Events

   • Heavy Rainfall begins in parts of North Cornwall
     • 12pm
   • River Valency is almost full after 3 hours of torrential rain
     • 3:15pm
   • A 3m Wall of water crashes into Boscastle visitor centre
     • Fast flowing water makes roads impassible
       • 4pm
   • Floods hit peak
     • 5pm
   • Floods start to recede
     • 6pm

3. Causes

   • Natural Causes
     • Heavy localised rainfall
       • L:and Saturates quickly
         • Water goes straight to Rivers causing it to overflow
     • Topography of the Land is steep valleys
       • The Valleys means that all the water is funnelled into the village
         • Therefore more surface run-off
         • Impermeable surfaces means that the water can't infiltrate into the ground
           • Ground is made of tarmac and slate
     • Narrow River channel
   • Human Causes
     • Boscastle stands on the Confluence of 2 Rivers (Jordan & Valency
       • This means there is lots of water passing through
       • The River has been walled in order to accommodate for the village
         • This means that the river couldn't adjust to the sudden increase in Water
     • The bridge constricts the flow of water
       • This forces the River to burst its banks
     • The village has been built on the rivers flood plains
     • The rivers capacity has been reduced in order for the development of roads & car parks

4. Effects/Impacts

   • 58 properties were flooded
     • 4 were swept away
   • There were no deaths
     • Around 100,000 residents and visitors were affected
   • 4 footbridges were swept away along the River Valency
   • Boscastle's infrastructure suffered major damage
     • Power and phone services were out
     • Roads were badly damaged
     • The total estimated damage was £2,000,000

5. Response & Solution

   • Solutions
     • A £4.5 million scheme was put in place to defend Boscastle
       • Better Drainage
         • New Sewer system installed
       • Land re-grading
       • Boscastle Car Parks were raised
       • River made deeper
       • Drains allowed water to run underground
   • Short Term Response
     • Sand Bags put in homes
     • Temporary Accomodation
     • 7 Helicopters sent in
       • Saved 150 people
     • Debris & Silt cleared
   • Long Term Response
     • Restoration
       • Roads & Bridges
       • Water & Sewage
       • Power
     • Donation/Charity
     • Banks & Flood walls were raised
     • River Jordan relief channel made bigger

Images and files in the map