Monday, August 20, 2007

Case Study of Coastal Erosion - Dunwich (Suffolk)

The Suffolk coastline of East Anglia has been eroding for 1000s of years and suffers rapid and frequent change - the changes are due to the coastal processes of erosion and deposition and the large scale movement of material down the coast by longshore drift.

Dunwich is a very small village located on the east coast in Suffolk. Dunwich was once a thriving port, similar in size to London, but storms, erosion and floods have almost wiped out this once prosperous settlement, which once had a population of 4,000 as well as a flourishing port. All that remains now are a few cottages - yet at one time there were 6 churches and 3 chapels. Most of old Dunwich now lies on the sea floor.

It is predicted that with our changing climate, storm events will become more frequent and in 1990, 7 metres of the coastline was lost over a few days in a storm that hit the Dunwich Coast.

So why is Dunwich so affected by coastal erosion?
- the coastline at Dunwich is made up of soft rock (sands, gravels and clays), these are easily eroded by the sea;
- the problem is made worse by the narrow beach which results in wave attack at the base of the cliff;
- the cliff faces are also greatly affected by weathering processes;

Rates of erosion at Dunwich are now as great as one metre per year. Material that is eroded from the Dunwich cliff line is moved down the coast by the process of longshore drift, keeping the beach fairly narrow. The material is transported in a N-S movement where it is deposited further south to form Orfed Ness Spit.

Although prone to severe coastal erosion, Dunwich has relatively little sea defence. An area of marshland just beyond the car park has been protected from the sea by a long shingle sea wall, but this has to be regularly rebuilt by bulldozers. Until recently there has been no other coastal management and the natural creation of a new beach to absorb wave energy has been seen as the most effective solution, due to the small size of Dunwich it has not be seen as cost effective to spend millions on sea defence at this location. However in February 2007, a new experimental beach stabilisation project began, it has been designed to try and reduce the severe cliff failures. A series of sand and shingle humps are to be created to stop the beach eroding and therefore help to reduce cliff erosion.

Another good example of coastal erosion is the Holderness Coast (Humberside)

Follow up links:
The Geology of Dunwich
Dunwich Photographs (Thanks to A Stacey "The Geography Department")
Low tide reveals lost city (BBC Article)
Work to shore up Beach to start (BBC Article)
Disappearing Village - sea claims another piece of Dunwich (Guardian Article from 1999)

Podcast: Case Study of Coastal Erosion - Dunwich
You can listen to a podcast of this post below - to download a copy to listen to on your .mp3 player click here.

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