The challenge of the sea...

This entry comes from the fantastic Writtle conservation team and looks at how the sea impacts on the environment.

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Winter is here and wouldn’t it be nice to jet off somewhere exotic and faraway? The Maldives perhaps? Or perhaps not…..it seems that particular island group is under imminent threat from rising sea levels. To be precise, the water around the islands is currently rising at 9mm a year and the islanders may have to leave their homes before the year 2100. 

But sea level rise is affecting us here in Britain as well, although clearly not in such a drastic manner. Have a look at a map of the Essex coast and the contour lines show how very close to sea level many of us live. With slowly rising sea levels and the prospect of increasingly unpredictable weather patterns, we have been forced to reconsider how we manage these threats, especially on the east coast of England. 

Image courtesy of federico stevanin at FreeDigitalPhotos.net 

The attraction of ‘hard’ defences, such as sea walls, has lost some of its appeal, not least because of the huge capital cost associated with constructing and maintaining such defences. So what to do? Over the past 20 years Essex has been at the leading edge of a new approach called ‘managed realignment’. This is a process whereby land which is currently protected by sea walls is returned to the sea by knocking through the walls and letting the water in. This way, the effects of any sea level rise or storm surges can be softened by allowing the water more room to spread out, thus reducing the overall impact, especially further up estuaries where waterways narrow.

The best known realignment sites in Essex are at Tollesbury, Abbotts Hall south of Colchester and now Wallasea Island. The sheer scale of these projects is hugely impressive in itself but this type of management is not always popular due to the loss of land which has previously been farmed. And indeed  those who oppose realignment often refer to it as ‘managed retreat’.

But one habitat which seems almost certain to benefit is that great Essex speciality, saltmarsh. In recent decades our saltmarshes have become squeezed between the sea and the sea walls. But by ‘relaxing’ the entire system of management and allowing the water in, we have begun to create new saltmarsh behind the sea walls where none has existed for (in some cases) several hundred years. We are perhaps, simply returning to the sea what was only ever borrowed.

For more information on our degree-level conservation courses, please visit our website: http://writtle.ac.uk/UG-Conservation-and-Environment