North Norfolk Dredging Induced Erosion in Eurosion Report

The following is an extract from ‘Living with Coastal Erosion’ — Eurosion Policy Recommendations — December 2003. To see the report in its entirety go to www.eurosion.org/reports-online/reports.html

Example Of Coastal Cliff Erosion

Happisburgh

The municipality of Happisburgh is a located in the county of North Norfolk (UK). Sediments are removed from the cliffs under the action of the waves and are transported southwards where they supply the beach of Sea Palling with “fresh” sediments. The two aerial photographs below depict the situation of the area of Beach Road in Happisburgh, in 1992 and 1999 respectively. Coastal erosion mainly affected the south-east part of Beach Road, and coincides with the destruction of the wooden defences originally located upfront the cliff.

Aerial Photo1  Aerial Photo 2

 
2.2.2. Human structures and activities have exacerbated coastal erosion
To a lesser extent, coastal erosion is also exacerbated by human activities which are implemented in some cases hundreds of kilometres away from their zone of impact. This has proved to be particularly the case for:

(ii) Aggregate extraction. Dredging of river and seabed for navigational purposes (i.e. deepening navigation channels) or constructional purposes (e.g. sand and gravel mining) removes an important amount of sediments. This creates a sediment starvation which is in certain circumstances compensated by (re)activation erosion processes along the shore areas. This has proved to be the case in a significant number of cases including Cove do Vapor (Portugal), the Western Scheldt estuary (Netherlands and Belgium), Donegal (Ireland), Cavado (Portugal), and North Norfolk (UK). In some cases, dredging activities, by modifying the water depth in the near-shore area, induce wave refraction which in turn modify the long-shore and cross-shore sediment transport patterns.

Addendum 22nd December 2005
Since the Eurosion report was written two years ago, following further dredging in The Wash and off Great Yarmouth, it has been found that the original sediment flow coming down the North Sea has all but ceased. See Southern North Sea Sediment Transfer Study.

Consequently Sea Palling has (up to now) had to receive regular beach re-nourishment by having sand pumped onto the receding beach. Thus that stated in the report is outdated by this new evidence. The sediment is no longer arriving at Sea Palling by sediment drift, but it is arriving there by being removed by the dredgers and then pumped ashore.

And this too is now outdated, as in September 2005 DEFRA refused the Environment Agency the vitally needed grant of £2,000,000 to pump 150,000 cubic metres of sand onto Sea Palling beach to maintain the defences.  This refusal undermines the tens of millions already spent and means the demise the essential defences there, with consequential sea entry at that point followed by the eventual loss of the inland villages and The Broads.


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