Correlations of Offshore Dredging levels with Coastal Losses

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Correlations of Offshore Dredging levels with Coastal Losses
"Our disappearing coast line" the story Pictures of the effects of coastal erosion	The Good Beach Guide 2000
The graph shows the delayed correlation between the accumulated levels taken by offshore aggregate dredging as Extraction in millions of metric tonnes (up to 1994 to when the figures were available), the sea incursion by the mean of the maximum and minimum tidal reach in metres as Tide Mark and the mean beach sand level stripped as Sand Loss) (up to 1997).
	The survey took place over a 10Km shoreline between North Winterton-on-Sea and California, Norfolk between 1972 and 1997, with samplings four times per year in January, April, July and October. Over the period studies the offshore aggregate removed rose from close on zero up to 260 million metric tonnes, whilst the mean tidemark encroached 115 metres and six metres of sand was stripped off the beach. Prior to the commencement of North Norfolk offshore sandbank dredging, these beaches were accrecating, as they had been since living memory. The loss of sand and shoreline came about soon after dredging started, to be further aggravated when dredging commenced between Winterton-on-Sea and Corton in Suffolk. Severe erosion then followed along the Suffolk coastline, later in Essex also.
Whilst sea rise due to Global Warming and East Anglian sinkage will in part have contributed to the loss of coastline and beach sand, the marked correlation shown powerfully links the shoreline losses to the retarded natural recapture of coastal sand deposits by the dredged out offshore areas. The increase of erosive wave energy due to the loss of offshore wave breaking potential is a further aggravating factor when sand and gravel are taken from areas immediately opposite the vulnerable coastline.