What did Dunwich used to be like? Right on the Eastern coast it was once a thriving port, similar in size to London but storms, erosion and floods have almost wiped out this once prosperous village which was the capital of East Anglia. All that now remains are a few cottages where once there was six churches, three chapels, two monasteries and even a mint. It's rumoured that most of it is under the sea and on a quiet day it's said you can hear the church bells of the doomed village still ringing out ... What Dunwich might have looked like…
Coastal Erosion at Dunwich… Why are the cliffs at Dunwich easily eroded?
They are made up of soft sands and gravels…
made worse by the narrow beach
as well as erosion by the waves at the base of the cliffs, they are also attacked by weathering!
When does the most erosion occur at Dunwich? Why is this?
Most erosion occurs during storms (due to high energy destructive waves)
At high tide – when waves are able to pound at the base of the cliffs.
Rates of erosion at Dunwich are now as great as one metre per year! Actively eroding cliffs – absence of vegetation shows that erosion is recent The line of pebbles show the high tide mark on the cliff Source of Photos: http://www.stacey.peak-media.co.uk/DunwichHeath/DunwichApril2005/DunwichApr2005.htm
This photo clearly shows two levels at which the base of the cliffs has been eroded at high tide! Photo Source:http://www.stacey.peak-media.co.uk/DunwichHeath/DunwichApril2005/800-P1010829.JPG
What is Longshore Drift? The large scale movement of material along the coast
In what direction does material move along the coast at Dunwich? Mark on the prevailing wind direction and draw on the pattern of longshore drift along the coast at Dunwich. Question – Get thinking! How does longshore drift contribute to the erosion problem at Dunwich?
Is there any coastal management at Dunwich today?
COASTAL MANAGEMENT WHAT ARE THE OPTIONS? HARD ENGINEERING SOFT ENGINEERING Coastal Defence Structures (man-made, which reflect large amounts of wave energy. Beaches or naturally formed materials used to control / re-direct erosion processes
2. RIP-RAP (Rock Armour) Advantages? Disadvantages? rip rap is simply boulders/stones the waves break on the rip rap and not on the coastline
3. GROYNES Advantages? Disadvantages? These stop Longshore drift trapping the sand and shingle and building up the beach to create a natural coastal defense against the waves which break on the beach rather than against the cliff.
4. GABIONS Advantages? Disadvantages? Although not used at Aldeburgh there are 2 other types of hard coastal defence: