Coasts case studies

How can cliff collapse cause problems for people at the coast?

Case study: Barton-on-sea, Hampshie

• Christchurch bay has long been affected by coastal erosion and cliff collapse
• Over the years a number of cafes and buildings have been lost at sea
• Extensive coastal defences have been built to prevent erosion
• In 2008 a fresh landslide occured which raised concerns about the vulnerability of this part of the coast

The cliffs are prone to collapse due to:

• The rocks are weak sands and clays, easily erosed by the sea and have little strength to resist collapse
• The arrangement of rocks (permeable sands on top of impermeable clay) causes water to "pond-up" within the cliffs. This increases the weight of the cliffs which encourages collapse
• The stretch of coastline faces direct force of the prevailing winds SW. With the long fetch, the waves are powerful and can carry lots of erosion
• Several small streams flow towards the coast but disappear into the permeable sands before they reach the sea- increases water in the cliff
• Buildings on the cliff top have increased the weight on the cliffs, making them more vulnerable to collapse. They also interferre with drainage

How can coastlines be managed?

Coastal defences

Case study: Minehead

• North coast of Somerset
• One of the regions premier tourist resorts and every year it is visited by thousands of tourists.
• By the early 1990’s it became clear that the current sea defences were going to be inadequate in the future.
• Storm damage was estimated at £21 million if nothing was done.
• The Environment Agency developed a plan to defend the town and improve the amenity value.
• Work started in 1997 and the sea defences were officially opened in 2001. The total coast was £21.3 million.

Main features

• A 0.6m high sea wall with a curved front to deflect the waves. The landward side is faced with attractive local red sandstone.
• Rock armour at the base of the wall to dissipate some of the wave power.
• Beach nourishment to build…