The largest coastal re-alignment in Europe - occurred in Essex
ANDREW MAY
Conservation Manager, Essex Wildlife Trust
Abstract
Saltmarshes are major inter-tidal habitats with specialised flora and fauna. They have high productivity
and contribute significantly to the estuary food web. Current and predicted rates of sea level rise are
placing pressures on the coastline particularly along the hard coastal defences, such as sea walls.
Over the next 20 years there may be the loss of 8,000 - 10,000 ha of inter-tidal habitat (Gilbert &
Anderson, 2000). Alternative flood defence techniques such as coastal re-alignment are being viewed
as useful and cost effective techniques for habitat creation, coastal defence and the opportunity to
reduce coastal squeeze. The target for habitat creation over the next 20 years for Essex has been
set at 1,000 ha. Various organisations created the largest coastal re-alignment in Europe last year
when over 80 ha of inter-tidal habitats were created by breaching 3.5 kilometres of sea wall fronting
Abbotts Hall Farm along the Blackwater estuary in Essex.
Introduction
Intertidal habitats are areas of bare or plant covered sediment between high and low water marks.
Saltmarshes occupy the upper levels of tire inter-tidal zone. In England there are approximately
32,500 ha of inter-tidal sand and mudflats with over 1.100 ha occurring within the Blackwater
Estuary. In Essex, estuaries form a significant part of the coastal habitats. In 1996 the mid-Essex
coast represented 70% (3.237 na) of the Saltmarsh habitat in Essex and 7% of the total area of
Saltmarsh in Britain. However 50% of saltmarshes have been lost over the last 30 years although
around 44% loss occurred in the Stour, in Essex, over 15 years (Gilbert & Anderson 2000; English
Nature 2000).
Essex lias the longest coastline of all English counties stretclung for over 300 miles and supports an
abundance of wildlife. However Essex is losing 2% of the total saltings area each year. Current and
predicted rates of sea level rise are placing pressures on hard coastal defences, such as sea walls.
These hard sea walls along this coastline arc preventing the Saltmarsh and inter-tidal areas from
migrating inland, which they would do under natural conditions in response to sea level rise. As a
result the outer edge of the Saltmarsh and the fronting mud-flats are undergoing erosion at a rate of
up to two metres annually. This extensive and continuing loss of marshes in south-east England is
therefore as a result of what is called coastal squeeze. Alternative solutions like coastal re-alignment
are being viewed as useful techniques for habitat creation and coastal defence. This will also allow
for the replacement of rapidly disappearing habitats and develop long-term sustainable approach to
flood defences and rising sea level.
Abbotts Hall Farm is situated along the Blackwater Estuary which is the largest estuary in Essex-
north of the Thames and part of the largest estuarine complex in East Anglia covering 4395.15 ha
(English Nature, 1995). The Blackwater Estuary is of international and national importance for
nature conservation with extensive areas covered by statutory designations - Ramsar sites (a world
wide designation of wetlands), Special Protected Areas (SPA) (a European designation which protects
the habitats of migratory birds) and Sites of Special Scientific Interest (SSSI) (a national designation).
One of the main threats to the Blackwater Estuary is coastal squeeze due to sea level rise winch
results from global warming causing sea level rise and isostatic forces operating on the land mass of
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Essex Naturalist (New Series) 20 (2003)