South Downs - United Kingdom

Complete description of case study





Title South Downs
National level United Kingdom
Regional level East Sussex


The South Downs area of the Sussex coast is taken into account together because this area forms one coastal cell. Although erosion has always taken place on the Sussex coastline, human intervention has recently increased erosion along the Sussex cliffs. Defending the soft cliffs against erosion causes a sediment deficit further downdrift and the construction of piers and groins causes an interruption of longshore transport, leading to leeside erosion. Furthermore, because sea walls and groins have largely fixed the coastline, the coast has lost its resilience.

Due to the relatively rapid erosion rates, most of the towns along the Sussex coast are at risk. Sea defences in front of the towns minimize the damage to property. However, along the taller cliffs damage cannot always be prevented. The major functions along the South Downs coastline are agriculture, tourism and recreation, light industry, nature conservation and residential development.

Until now the policy option has been to hold the line in places where significant infrastructure or housing concentrations are present. A changing policy has been adopted over the last few years: the coast should be left to natural changes as much as possible, for aesthetic and technical reasons (protection decreases sediment supply areas further downstream). The community’s interest is put above individual interests. This viewpoint, of course, leads to many conflicts, but the policy of holding the line will only be applied if large concentrations of people or big investments are threatened.


Coastal characteristics
  • Study area: 84 km
  • Type of coast: soft rock coast, shingle beaches
  • Tidal regime: macro tidal (mean tidal range= 4.7m)
  • Range of waves : 1,6 % of mean Hsig > 3m ;annual nearshore Hmax >3.5 m; every 200 years nearshore Hmax >5.0 m
  • Other: sea level rise= 6 mm/year; river discharge
Policy options Historical: hold the line
Present: managed realignment
Socio-economic activities Agriculture, tourism and recreation, light industry, nature conservation and residential development.
Engineering techniques Seawall, groins, shingle nourishment.


Name Paul Sistermans
Odelinde Nieuwenhuis
Institution DHV group
Address Laan 1914 nr.35, 3818 EX Amersfoort
PO Box 219 3800 AE Amersfoort – The Netherlands
Telephone / fax +31 (0)33 468 37 00 / +31 (0)33 468 37 48