Holderness – Europe’s fastest eroding coastline. (Case study)

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Dan Grist
Holderness ­ Europe's fastest eroding coastline.
3 physical reasons why erosion is so rapid:
Geology ­ There are two types of rock on the coastline; chalk and boulder clay. The chalk
e.g. at Flamborough head is fairly resistant, and produces features such as cliffs, caves,
arches and stacks. Whereas the boulder clay has little resistance to erosion, especially when
wet. It produces shallow sloping cliffs, and it is these cliffs that are eroding on average of 2
metres a year.
Fetch ­ Holderness is exposed to winds and waves from the north east, with a fetch of
around 500-800km across the North Sea.
Longshore drift and beach material - there is never enough sand to stop the waves
reaching the cliff base at high tide, the narrow beaches offer little friction to absorb the
wave energy and protect the cliff. The sand that is produced is taken southwards by
Longshore drift, leaving Holderness poorly protected against the waves.
Hard engineering strategies
There are two rock groynes, coting £2.1 million at Mappleton in order to protect the major
coastal link road which is very important to the local economy. However it is causing
terminal groyne syndrome.
At Withernsea there are integrated defences which cost £6 million. The defences included a
concave splash back sea wall, wooden groynes to intercept the LSD and rock armour "Rip
Rap" (10 tonnes granite blocks)
There are revetments at Easington ­ which protects the gas terminal. The revetments absorb
the energy of the waves and therefore protecting the coast line (holding the line.)
Soft Engineering (sustainable) strategies
Beach nourishment at Hornsea ­ this creates a wider beach to protect the cliff line and
adds sediment into the coastal system so that areas down drift benefit.
Coastal zoning ­ used by planners to divide stretches of coast into land use zones. Red lining
identifies these zones at risk or erosion where the costs of protection exceed the possible
benefits.
Managed retreat ­ a policy is adopted whereby existing residents have to "roll back" away
from the cliff. Residents agree to demolish their existing homes and build a new one inland.
DEFRA add the Environmental agency now use integrated coastal management zones (ICMZ's),
which means that sections of the coast are managed as a whole, rather than individual towns or
villages. Coastal engineers have realised that protecting one area can makes things worse for
another i.e. terminal groyne syndrome. This is due to sediment cells; in each cell, sediment moves
around between the beach, cliffs and the sea. The coast of the UK is divided into a number of
sediment cells, which form the basis of these management plans. E.g. the Holderness sediment cell
extends from Flamborough head to the wash. Engineers now consider a whole cell and devise plans
that apply to the whole stretch of coast; shoreline management plans (SMPs). These SMPs either
result in doing nothing, holding the line, advancing the line or retreating the line.

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