Coastal erosion

A detailed Summary of Coastal erosion

For many decades the approach to rapid coastal erosion was to build up sea defences, to try and slow down or even stop the erosion. Initially the attempts were thought a success, however after some years it was realised that the power of the sea and waves could overcome human attempts. Only could protection be a success if huge costs were going to be involved. Many methods around the British Isles have taken place in he last 50 years with many failures occurring. It is very rare to find a coastline that shows a decrease in the rate of erosion over many years after defences are in place. In fact in places the defences seem to have speeded up the erosion process. Coastal erosion is a natural process of erosion, transportation and deposition, interfering with this balance could be to blame for the rise in erosion on the coasts of some areas.

Groynes have been built out to sea in many areas of the British coastline. Their aim is to trap material and thus slow down the rate of longshore drift. However, these groynes in some areas are been blamed for the rise in erosion rates further down the coast.

On the Holderness coastline in Humberside, erosion is taking place at a rate of about 2 metres per year. Along this coast there i

Gravel extraction occurs in many offshore areas around Britain, gravel is removed in large volumes for commercial purposes each year. More than 20 million tonnes were been dredged in 1989. The removal of this gravel was thought to be a good method, as no extra quarries would have to open therefore creating no protests from any local people. The problem is removing all this sand and gravel is leading to the gradual wearing away of shores and cliffs, adding to coastal erosion. When large amounts of material are removed from the seabed, the directions of currents move more material back into the dredged area. The area dredged will be replenished with material, and this material will be taken from elsewhere along the coastline. Dredging is taking place offshore from Barton on Sea, near the Isle of Wight. Like Holderness, Barton on Sea suffers from coastal erosion at an alarming rate, and longshore drift is also present. At Barton, a spit has also developed because of the longshore drift. Barton is also an area that has suffered heavily from landslides on the coast in the past, because of the layers that make up the cliff. Heavy rain causes the initial problem, infiltrating into the permeable material. It can then not pass through the clay layer, so flows outwards horizontally emerging as a spring. This lubricates the layer, removing the friction between layers. When the weight becomes too much, the cliff slips creating a landslide. Many things have been done to the coastline to slow the rate of erosion, but the construction of a groyne at Hengistbury Head has made matters worse. Sediment travelling east to west has become stuck on the east side of the groyne to form a beach. This has limited the amount of sediment moving further along the coast by longshore drift. So now, the only sediment to reach Barton is silty material brought into Christchurch Harbour by the rivers Stour and Avon. And, material which is eroded from the cliffs at Plateau Gravels. Therefore, with the building of the groyne and removal of offshore gravel, erosion rates have increased at Barton. This is because a reduce in the amount of available sediment for the beaches, leads to the beaches s

Some common words found in the essay are:
British Isles, Spurn Head, Plateau Gravels, Cowden Farm, Barton Sea, , Hengistbury Head, Easington Gas, coastal erosion, longshore drift, Stour Avon, sea defences, meant material, Christchurch Harbour, rate erosion, coast longshore drift, sea wall, drift barton, wave energy, glacial till, form beach, rate longshore drift, moving coast longshore, longshore drift barton,

Approximate Word count = 1464
Approximate Pages = 6 (250 words per page double spaced)

Category: Science