The coast of West Sussex – Past, Present and Future

Tuesday 10th October 2017 ‘The coast of West Sussex – Past, Present and Future’ Uwe Dornbusch, 10 October 2017
Uwe Dombusch works for the Environment Agency as a senior specialist in Coastal Flood and Erosion Management.
He presented a number of photos, videos and graphs showing how the Sussex coast has undergone significant change not only over tens of millennia but also in the more closely documented period since Roman times. The picture opposite shows the erosion around the coast off Selsey: it will be noted that the shoreline has receded by between 3 to 6 Km.
Uwe showed a number of photos illustrating how the sea tends to have its own way, especially in low lying coastal areas, despite attempts by man to control things. The picture opposite shows the narrow shingle ridge topped with a small stub wall at Atherington being overwashed by a large wave at high tide.
(Uwe had to wait for 10 minutes to capture a wave high enough to overtop the wall.)
The Chichester harbour /Selsey Bill/Pagham harbour coastline does seem to be especially ‘active’. The picture opposite shows the outline of present day coast-facing houses in Pagham, superimposed on an 1874 map of the area. During this time the harbour entrance has moved some 1000m to the SW, prompting the urban development shown, and leaving a lagoon behind said houses.
The picture opposite illustrates the frequent recycling work needed to keep shingle in its ‘desired’ place – typically determined by local housing and road building developments. The erosion shown here can take place over just a few tides.
Uwe later attempted to sum things up by saying “increasingly we have to decide if we want to keep houses where they are, or preserve the beaches, but not both”, implying that holding beaches can demand hard engineering structures (e.g. concrete pouring) – and even these can be eroded and require toe protection and further extension. Another significant consideration, leading to variations in erosion behaviour, is the nature of the beach material itself. Large shingle behaves differently from sand, whilst the prognosis for a mixture of materials in between is even harder to model.
Uwe discussed the effect of rising sea levels. The picture opposite shows predictions of sea level rises over the period 2000 to 2100, varying from 100mm to 700mm depending upon how nations manage to control emissions of greenhouse gas. There is also a rather worrying red line showing a possible 2m rise over this period should the melting of ancient ice significantly accelerate. A new report on the impact of future climate change is anticipated for 2018 which will include a better understanding of the contribution that melting ice from Greenland and Antarctica will make.
The presentation was followed by a lively debate prompting our speaker to show some more illustrations in response to detailed questions as follows.
The need to move shingle that has been washed along the coast by wave action is a constantly occurring problem. Shoreham Port currently use diggers and lorries as illustrated opposite. A method that shows a more dramatic wayof moving shingle is also shown: shingle, dredged from offshore, is ‘rainbowed’ onto the beach from a ship.
It was a most interesting talk with a correspondingly large (77) audience. Clearly Uwe and his colleagues have an interesting and never ending job advising the various coast-facing authorities on the technical options for dealing with the all-powerful, restless sea.