Tuesday, 31 January 2012

Coastal erosion

I've seen a report that shows the total erosion along parts of the East Yorkshire coast. The coast is one of the fastest eroding coastlines in Europe. The average rate of loss is about 2.5 metres each year, but last year there were unusually large losses in a few areas. South of Withernsea the cliff receded by ten metres. Near Waxholme seven metres disappeared.

Holderness is a rich agricultural plain east of Hull. The clay it is made of was deposited as the last glaciers melted about 10,000 years ago. As the sea level rose again separating England from modern-day Netherlands and Denmark the soft clay became the new coastline. The cliffs range from a metre to tens of metres high, but the action of the sea easily undercuts the cliff and then causes collapse. The very dry year last year may have contributed because the clay shrinks as it dries out, leaving fissures that make collapses easier. Most of the coast is not, now, defended so these loses will continue, but probably at the average rate overall.

Left to itself, in about 10,000 more years, the plain would probably erode back to the old coastline which was a limestone line marking the edge of the Yorkshire Wolds from Flamborough Head to Hessle on the bank of the Humber.

All this erosion makes keeping the OSM coastline up to date is hard work.

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