Dungeness
COASTAL CASE STUDY
Description
Dungeness is a relatively flat and low-lying coastal geomorphological feature in southern Kent called a 'cuspate barrier' (also known as a cuspate foreland). A cuspate barrier forms through the accretion of shoreline materials transported by broadly opposing longshore drift directions. The accretion of sediment causes the shoreline to prograde offshore, forming a triangle-shaped prism of sediment. At Dungeness, the cuspate barrier has formed over the past 5000 years, fed by the longshore movement of largely flint gravels from both the west and the east.
The current landscape of Dungeness is characterised by a series of low-amplitude, sub-parallel shoreline ridges (composed largely of gravel) separated by lower-lying areas that formed back-beach depositional areas (composed largely of finer materials). Dungeness is an area of considerable international importance relating to both its geomorphology and floral and faunal biodiversity; this is reflected in its wide range of conservation designations.
Value to the nation:
- Tourist area: barren landscape that attracts one million visitors annually
- Nature: RSPB bird sanctuary
- Wildlife: designated Site of Special Scientific Interest (SSSI), Special Area of Conservation (SAC) and National Nature Reserve (NNR); one of the best UK sites for species of insects, moths, bees and beetles
- Utilities: nuclear power stations; two lighthouses; end of the line for the Romney, Hythe and Dymchurch Railway; Lydd airport
Location
Dungeness forms a headland in Kent sheltering a large area of low-lying land. Dungeness is situated approximately 20 miles south-west of Folkestone.
Geology and the coastline
The bedrock geology at Dungeness is composed of layers of sandstone, siltstone and mudstone, known as the Hastings Beds Subgroup. This sedimentary bedrock was formed approximately 134 to 145 million years ago in the Cretaceous Period, when the local environment was dominated by swamps, estuaries and deltas.
The bedrock geology is concealed by the superficial geology, which comprises predominantly of storm beach deposits, tidal flat deposits and small amounts of blown sand and alluvium. These deposits are dominantly shallow-marine to coastal in origin. The Dungeness headland has been gradually undergoing accretion where sand and gravel is built up into a shingle bar through the processes of longshore drift.
Image - the shingle beach here shelves steeply into the water and boats are stored on the beach-top when not in use. The area is littered with dead boats as well as active ones, and the winches, rails and sheds associated with getting them in and out of the water.
Boats on the shingle at Dungeness cc-by-sa/2.0 - © Richard Law - geograph.org.uk/p/2067113
GeoCoast data
Coast type
A simple four-fold classification that identifies the spatial situation for each grid cell. Each cell identifies a lithology and its coastal setting.
Foreshore and backshore data, onshore (beyond the backshore but within the forecast inundation zone) and offshore (area below low-water line) coverage
Cliff height
Estimated cliff height in metres, determined from digital terrain model (DTM) analysis. Measured from the high water line to cliff top.
Height in metres from 0 - >100 m
Cliff erosion
The worst-case erosion susceptibility classification of the cliff or backshore deposits. Click on a cell in the map for more information.
Cliff erosion, worst class scenario.
The mean erosion susceptibility classification of the cliff or backshore deposits. Click on a cell in the map for more information.
Cliff erosion, mean class scenario.
The base lithology (lith1) erosion susceptibility classification of the cliff. This is the first lithology above the high-water line that will be predominantly subjected to wave processes.
Cliff erosion, base lithology (lith1) erosion susceptibility classification of the cliff.
Inundation
Maximum sea-level inundation extents as defined by UK Climate Projections , UKCP18 sea level rise climate scenarios for future sea level rise
Maximum sea-level inundation extents.
Subcoast potential subsidence rate (PSR)
The potential subsidence for an area considering the combined effects of the geological factors at that location. Provided as % and mm/yr.
Potential subsidence rate in mm/year.
Area statistics
A range of regional statistics have been generated from the baseline datasets to provide an authority-level overview of coastal properties, cliff erosion and flood susceptibility. These are all provided under the Open Government Licence .
- Coastline cliff erosion: the erosion susceptibility classification based on the geological properties showing the worst and mean scenarios for the coastline
- Multi formations: length of coastline that is made up of cliffs with multiple different geology layers
- Inundation: maximum sea-level inundation extents as defined by UK Climate Projections — UKCP18 sea level rise climate scenarios for future sea-level rise
These are available in the BGS Onshore GeoIndex .
Coastline management
Dungeness falls within the Shoreline Management Plan for South Foreland to Beachy Head (SMP 11) , specifically the section between Sandgate to Cliff End. As previously described, the landscape of Dungeness is relatively flat and low-lying, situated adjacent to and in some cases beneath sea-level. This creates a significant risk of flooding which could impact about 16000 properties and approximately 220 km 2 of agricultural land. Dungeness also hosts the Dungeness B Nuclear Power Station, although the process of decommissioning the two gas-cooled reactors began in 2021.
Dungeness exhibits a mixed coastal frontage comprising:
- slightly raised areas of beach gravel ridges,
- inter beach ridge topographic lows
- sand dunes
According to the SMP, for the slightly raised areas of frontage, the continued supply and replenishment of beach materials mean that the beach barrier is self-sustaining. However, some secondary embankments may be needed to restrict flooding. By contrast, the lack of natural sediment supply to the intervening topographic lows means that, if the primary defences were either removed or failed, there would be an immediate risk of coastal inundation. The sand dunes at both the western (Camber) and eastern (Romney) ends of Dungeness also provide a natural flood defence.
The frontage at Dungeness B will be managed for the next 100 years. Although some minor realignment may occur during decommissioning, eastwards longshore sediment movement will continue to be maintained.
Image - a view of the shingle beach looking west on the Dungeness peninsula in Kent. Dungeness is the largest vegetated shingle peninsula in Europe.
Sea Fishing on the Beach cc-by-sa/2.0 - © John P Reeves - geograph.org.uk/p/6392234
A range of regional statistics have been generated from the baseline datasets to provide a Shoreline Management Plan-level overview of coastal properties, cliff erosion and flood susceptibility. These are all provided under the Open Government Licence .
- Coastline cliff erosion: the erosion susceptibility classification based on the geological properties showing the worst and mean scenarios for the coastline
- Multi formations: length of coastline that is made up of cliffs with multiple different geology layers
- Inundation: maximum sea-level inundation extents as defined by UK Climate Projections — UKCP18 sea-level rise climate scenarios for future sea-level rise
These are available in the BGS Onshore GeoIndex .
Aerial photographs
Comparison of the Romney Marsh, Dungeness area over an 80 year period. 1940 (left image), 2020 (right image). Google Earth © 2020 Infoterra Ltd & Bluesky. Image NASA
Onshore and offshore data from BGS
Onshore and offshore agencies and media:
Gallery
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