British Costal Erosion

24 Jul

“It is horrifying that we have to fight our own government to save the environment.” —Ansel Adams

In the 1980s, costal erosion was a major problem along the coast from Overstrand to Trimingham. What this erosion does is to destroy land. For instance from 1885 to 1970 this coastline has receeded a quater of a kilometer inland. The sea causes erosion in three main ways:

First longshore drift, this is when the sea washes beach material down the coast and away from the cliff, leaving the cliff exposed to the full force of the sea.

Secondly hydraulic action, this occurs when powerful waves lash the cliff face, forcing air into tiny cracks. The pressure that builds up enlarges the cracks and weakens the cliff.

Finaly corrasion, or abrasion, occurs when the sea churns pebbles and sand against the base of the cliff.

All of these processes are attacking the cliff and in addition the cliff is weakened by cliff face erosion. People are affected directly by the cost of replacing what is lost. The land that is lost is covered by trees, vegitation, forests, roads, housing, farmland, soils, heritage, churches, castles, sites of antiquity, industry etc. Replacing buildings and relocating communications is very expensive. It is impossible to renew our heritage. Farm land is very expensive, but there is an even worse problem when an industry loses land. Even if the factory is not destroyed, the company will in all likelyhood look for a new site elsewhere. This causes unemployment and stretches people to the limits of their budget.

In the previous example of costal erosion between 1885 and 1970 mostly farmland was lost but also St. Michaels Church. One road had to have a major diversion built in it because part of the old route had fallen away. As mentioned the coastline has receeded inland. This has happened along roughly three kilometers of coastline.

In a hundred years time, without improvement in defences, the coastline will have receeeded a further square kilometer. This will take more land, most notably Manor Farm, and buildings, especialy historicaly important St. John the Baptists Church. Not only that, a substantial amount of housing will be lost along with road links and of course all the pipes and wires that run under the roads, i.e. phone lines, water, gas etc.

It is important to take steps to prevent this now which will cost far less than allowing further disruption. The coastline from Overstrand to Trimingham is roughly three kilometers in length. The options and the costs are as follows:

Sea walls £2,000 every 1m
Groynes £6,000 every 2m
Revetments £1,000 every 1m
Gabions £0,350 every 1m

The most effective sea defence is sea walls used in conjunction with groynes. However this costs £15m budget (£10m over budget). Although it must be considered that this will last the longest. Because there is not this money I recommend that revetments be used, which cost half as much as sea walls, along the entire coast affected. This will cost £3m and a further £90K for groynes along the same coast with groynes to prevent long shore drift.

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Posted by on July 24, 2011 in Society


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