Mappleton

• Location of Mappleton:

  • 3km South of Hornsea, Holderness Coast
  • 50 homes, 50 businesses, cliff 50m from the road
  • B1242
• Geology of Mappleton:

  • Lies on unconsolidated till
  • Boulder clay - soft, erodes easily
  • Deposited by glaciers during the last ice age 18,000 years ago
• In 1991 almost £2 million was spent on two rock groynes and a rock revetments to protect Mappleton and the B1242 road. Blocks of granite were imported from Norway for the sea defences.​
• The purpose of two rock groynes was to trap beach material. By retaining a wide, sandy beach between the groynes, the sea would not be able to reach the base of the cliffs at Mappleton
• The cliff between the two groynes had been stabilised through landscaping and vegetation cover
• The coastal defences have been effective in reducing erosion between the two groynes. ​As the result of these coastal management strategies a substantial beach had been retained between the groynes halting erosion.
• Further south, the rate of erosion has increased significantly. This is because material which is being carried south is not being replaced (trapped in the groynes). Therefore there is no beach to protect the cliffs.
• Cliff regrading - Lower the angle of cliffs to stabilise ground.​

  • Strengths- Works on clay or loose rock where little else will​
  • Weakness - Retreat of cliff line uses up valuable land​
• Revetments – Massive rocks , made of granite, used to reflect rather than resist waves​

  • Strengths - Traditional solution to protect valuable resources, high-risk property or densely populated areas but cheaper than sea walls.​
  • Weakness - Costly and do not cope well with very strong waves
• Groynes – Rock or wooden types, hold beach material threatened by longshore drift erosion​

  • Strengths -Low capital costs and repaired relatively easily​
  • Weakness - Need regular maintenance. Cause scour downdrift and have wider impacts
• Beach nourishment– Sand pumped or transported to replace losses by long-shore drift​

  • Strengths – Appears ‘natural looking’ process​
  • Weakness - Expensive and may soon erode. Possible ecological effects
• Figures:

  • 1991 almost £2 million ​
  • Two rock groynes and a rock revetment ​
  • erosion at a rate of 2.0m per year​
  • B1242 coastal road​
  • Protect Mappleton,50 properties​
  • The road being only 50m​
  • 1 million m3 of sediment from cliff erosion ​
  • 2 million m3 from the erosion of the seabed up to 2 km offshore – 3 million m3 in total.