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Porlock summary
Porlock Weir is a small gravel barrier which encloses a lagoon, wet grassland
and 'improved' grassland and arable. The origins
of the gravel barrier lie in the erosion and longshore drift of material derived
from adjacent cliffs. The present position of the ridge has been 'protected'
by the erection of groynes and shingle recharge. A decision in 1985 not to continue
to 'protect' the ridge by the Environment Agency was met with much local opposition.
However, in 1996 a storm caused a breach in the ridge which rolled back some
40m and flooded the land behind. The new ridge was wider than the pre-storm
'managed' profile. It is concluded (Orford et al.
2001) that the breakdown
in the ridge is due to three factors relating to relative sea
level change, storm events and history of human interference.
| Site Name |
Porlock Ridge and Salt Marsh |
| Protected Status |
Site of Special Scientific Interest |
| Area |
180ha |
| Geographical location |
North Somerset |
| Local Planning Authority |
Exmoor National Park Authority |
| District |
West Somerset |
| OS Grid Reference |
SS 888779 (Centre of site) |
| Principle features/habitats |
Geomorphological
(N); saltmarsh
(N); vegetated
shingle (N); coastal wet grassland |
N denotes national importance for feature
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Guidance: The evolution of the ridge and history of 'protection'
of the hinterland from flooding has been the subject of a number of studies
related to the need for sea defence structures. Since the 1996 breach
no further management of the shingle ridge has taken place. As a result
the site provides an extremely valuable example of, and lessons
for, a 'do nothing' option. This is one of the casework sites included
in the "Guide to the management and restoration
of coastal vegetated shingle".
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References
Orford, J.D., Jennings, S.C. & Forbes, D.L.
2001.
Origin, development, reworking and breakdown of gravel-dominated coastal barriers in Atlantic Canada: future scenarios for the British coast.
In: Ecology & Geomorphology of Coastal Shingle, eds.Packham, J.R., Randall, R.E., Barnes, R.S.K. & Neal, A.Westbury Academic and Scientific Publishing, 23-55.
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