The Essex estuaries

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Temps de lecture : 3 minutes  

ESSEX ESTUARIES

A coastal county at the door of London

The County of Essex is in the south-east of England and lies just to the north-east of London. The coastline around its south- east edge is deeply indented, but flat, due to several river estuaries enclosed between those of the river Stour to the North and the river Thames to the South. Essex has always been an agricultural county, with a clay based but fertile soil and superb grain growing countryside – the subsequent grain giving rise to associated milling, malting and brewing industries. Livestock is common as well. Plant nurseries and market gardens abound where the clay soil is covered by lighter, more fertile soils. The coastline has also brought great wealth, with important trading, fishing and shipbuilding centres. Sea salt from Maldon, oysters from Colchester and cockles at Leigh-on-Sea are famous nation-wide. Today Essex is home to Tilbury Docks, the Port of Harwich and Bradwell Power Station. Its area is 3672 km2, and its population around 1.5 million.

Coastal lowlands challenged by the sea

Extensive areas of salt marshes, mudflats and offshore sand banks fringe the Essex coast. The area also includes grazing marsh, small areas of shingle shore, as well as coastal cliffs to a smaller extent. Landward areas are low-lying and mainly dedicated to agriculture. Much of these areas are protected from inundation from the sea by earth, sea walls and concrete embankments. […]For the whole country, over 1,8 million residences and 180,000 commercial properties are considered at risk, potentially5 million people, and 1,4 million hectares of agricultural land […].The total value of the assets at risk is estimated to be over 350 billion Euro for England. All the estuaries show signs of erosion and from North to South there appears to be a general decline in beach levels. This is most noticeable in the salt marshes. In the North this is attributed to the poor supply of material from the north with the approaches to Harwich Harbour forcing the material seawards. […] Losses due to enclosure and subsequent use for agriculture amounted to some 4,340 ha.

Accelerated sea level rise: a new threat?

Beside its exposure to coastal erosion processes – either nature or human driven – Essex has to face another threat. Its coast lies in an area where sea level is rising relative to the land. Sea level rise respectively reaches +1.7 mm/year in Stour Estuary, +1.4 mm/year in Crouch estuary, and +1.5 mm/year in Swale (Kent). A well known effect of sea level rise is the depletion of salt marshes, which provide a high level of safety by absorbing wave energy during storms. […] Acceleration of the pace at which sea level is rising, as observed today, could therefore jeopardize the ability of salt marshes to provide cost-effective protection to the hinterland against the risk of flooding.

Current shoreline management strategies

The Essex coast provides a good example of the way in which the policies associated with coastal defence, particularly those relating to protection of the land from erosion and flooding, have developed over the last 20 years or so in the United Kingdom. Since then the loss of habitat, changing perceptions of the implications of sea level rise and cost of maintaining hard defences have all contributed to the move away from ‘protect at all costs’ to a policy of ‘realignment’ which accepts that some land will be lost to the sea. This combined with the use of ‘softer’ engineering options, such as beach recharge, represent a much more flexible approach to coastal protection. However, it does not imply that the policy supersedes all locations where coastal protection may be in place. Indeed there are several large towns and villages where protection is desirable and cost effective because of the assets they protect. The identification of the most sustainable approaches to manage risk along the shoreline over the next 50 years has been supported by the elaboration of the Shoreline Management Plans (SMP) at the level of each coastal sediment cell, recommended by the Department for Environment, Food, and Rural Affairs (DEFRA) and the Environment Agency. The SMP for the Essex Estuaries was enforced in 1995.

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