The river walls on Orford Ness were originally built to create and then protect rich grazing land from what had been salt-marsh.
The creation of such large new areas of grazing land required a heavy investment and for this reason only rich landowners could afford it, in this case probably King Henry II in the late 12th century.
On the Airfield site the banks have stopped salt water from flooding the marshes on high tides and as a result have created what are now essentially freshwater marshes. On Kings and Lantern Marshes, although the bulk of the salt water has been prevented from flooding onto the marshes there is more seepage and also periodic inundations from the sea when the natural shingle sea bank is over-topped. As a result these marshes are more brackish in nature.
The elongated lagoons at the base of the wall are typical of 'borrow pits' where clay was 'borrowed' to create and then maintain the river walls. Some seepage of river water through the walls makes these watercourses slightly brackish. Areas where seepage occurs are often visible by the salt-marsh plants that grow at the base of the wall.
In purchasing Orford Ness from the Ministry of Defence in 1993, the National Trust inherited a number of river defences that had suffered neglect over several years and consequently were in a very poor condition. (The Environment Agency (EA) accepts no responsibility for the river walls on the property.)
Since 1993 the Trust has developed a management strategy for river defences based on strategic, practical and financial considerations. It was clear that the site could be divided into three principal areas of defence in terms of future and current importance as well as wall condition. The first, the Airfield site, holds the main infrastructure for the management of the site (i.e. offices, workshops, accommodation and visitor facilities) as well as important wading bird breeding grounds. As a result this area is considered the most important from a strategic point of view and co-incidentally the river walls are also in the best condition, due mainly to the protection offered by the salt-marsh in front of them.
The plan is to hold and maintain these walls in the long-term. The second area, Kings Marsh, is important for coastal brackish lagoon habitats and further grazing marsh. The walls in this area were extensively repaired during 2000 and the aim is to hold and maintain these in good condition for at least the medium-term.
The third area, Lantern Marsh, can be divided into two sections - upper and lower. The walls in the lower (southern) marsh will be treated as those in Kings Marsh, however, the walls in the upper (northern section) were inherited in a very poor state being particularly badly eroded and weakened and consequently were likely to breach in the short term. Read more about the DEFRA habitat scheme.
Find out more about birds at Orford Ness
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