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?
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.
- 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…