Beach and Dune Erosion

The Stages of Decay

beach erosion 1
An extensive natural beach and dune system prior to offshore aggregate dredging and consequent sand draw downdraw down The process by which tides and wave motion remove (draw down) material from a beach and pull it out to sea. A sandy beach experiencing draw down is thus denuded of its sand. The process can be natural (i.e. winter storms) or can be artificially caused (e.g. aggregate dredging, whereby the dredging of sand and gravel offshore causes sand to be drawn down from the beach in order to replace the material which has been dredged). Although high tides, steep waves and the strong winds of the winter partly erode the beach to export the sand offshore on the undertow, the sand returns during the summer months when offshore winds predominate. The sea rarely covers the beach, so allowing the wind to blow the dry sand surface particles inshore to build the dune system.

 

beach erosion 2
Sand stripping brought about by offshore demand causes a lowering of the sand depth to allow the sea to come further up the beach, consequently giving a permanently damp surface preventing the wind blow of dry sand to aid dune accretion. Both the beach and the dunes become foreshortened as a result.

 

beach erosion 3
The sea finally reaches and undermines the former protective dune base eventually destroying it, with no opportunity remaining for its replacement. Access to the beach is denied and both aesthetic and protective qualities become lost. Once this stage is reached it becomes very difficult to replace the original status.

 

The first photograph shows our Hemsby bungalow ‘Riskit’ sitting high on the dunes in 1978 before intensive offshore aggregate dredging commenced. It had then three other dune hills and 100 metres of beach between it and the sea, as had been the case since it was built in 1932.

 

 

 

 

The second picture shows one of these deep cuts that took a further two metres of sand from the beach, so allowing the sea to come up to the last remaining dune that the bungalow stood on. Two lines of bungalows were destroyed. On the last day of February 1988, further escalating beach erosion allowed a rough sea to take the dune our bungalow stood on, precipitating it into the sea.

 

 

The last photograph shows this. Within an hour all had washed away with not a trace remaining. Altogether 98 bungalows were lost at Hemsby North Marrams, where now only five remain on the landward side of the last remaining one third of an original 30 metre wide 13 metre high marram dune.

 
 
 
Pat Gowen   5th March 2005

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