The Pevensey Levels lie in a howl surrounded by the towns of Eastbourne, Polegate, Hailsharn and Bexhill. They are protected from the sea by a shingle ridge sea defense.
The history of the lowland marsh area between Eastbourne and Bexhill, today known as the Pevensey Levels, is dominated by the changing relationship between land and sea.
The first record of Pevensey, tinder its modern name, is in a charter of the 10th century - little is known about the earlier Roman settlement. However, it is commonly thought that even in Roman Times, some form of shingle beach existed roughly on the line of the present shore. There would have been significant gaps in the beach to allow out the low of the forerunners of the Pevensey and Wallers Havens. High tides would have also entered through these gaps in the beach.
There is no evidence of Roman occupation on the marshland behind the beach, which it is presumed was un-reclaimed, so that at high tide most of the level was a lagoon. Boats would have been able to moor at Pevensey Castle that was located on a peninsula guarding the mouth of the estuary of the Pevensey Haven. At high tide there would still be many small islands of higher ground protecting above water level and evidence of this exists in place names that have the suffix 'ey' or 'eye' - the ancient term for an island (e.g. Manxey or Horse Eye).
It is uncertain when reclamation of the marsh began, but it appears that little or none had occurred by 1086 when the Doomsday Book records that the edges of Pevensey Marsh reputedly supported 100 salt works.
By the time of the Great Flood, in 1287, almost all of the present marshland was reclaimed. The flood affected a large area and resulted, two years later, in the appointment of the first recorded Commissioners of Sewers for the Sussex Coast.
The underlying problem faced throughout history has been that as soon as the marsh is dammed off to prevent the sea coming in it is only possible to discharge freshwater out to sea at ebb tide. This then leads to the risk of flooding the land behind the sea wail.
When the first Commissioners dammed off the Pevensey Haven (somewhere near the current Pevensey Bridge) they also had the additional problem of the Haven silting up, thus reducing the capacity for vessels entering the port.
The reason so much time and money was spent on reclaiming the marshland was because the value of the recovered land was greater than the established upland, as it was far more fertile. Indeed, during the 14th century the area was considered to contain some of the most valuable arable land in the count~ supporting a large population. However, the land began to suffer more and more from freshwater flooding and by 1402 the entire area was again under water. To cure this problem a new cut was made from what is now Middle Bridge on the A259 to a new outfall at Normans Bay. This was a forerunner of the Wallers Haven.
Whilst the risk of freshwater flooding has been alleviated, the power of the sea began to cause problems. The Commissioners at this time were not responsible for the maintenance of the sea walls since they were monastic properties. With the dissolution of the monasteries the sea walls were neglected and drifting shingle blocked the tidal channels resulting in the area between Pevensey and Bexhill being reduced to salt marsh.
The battle to keep the Haven mouth open to shipping continued until 1st November 1694, when Engineer, William Markwick was engaged to build a new sluice at the mouth of the Haven and cut off all the remaining tidal creeks which were soon drained. From time to time major works have had to be carried out to balance the risks of freshwater and tidal flooding. Examples of this are the construction of the Pevensey New Cut and Sluice in 1748 and in the period between the late 1950s and 1980 a number of schemes were implemented to improve the drainage of the marshland to enable the land to be used for arable production and to guard against flooding during periods of tide-lock.
Since much of the area is significantly below high tide level (typically +2.0 A.O.D. or lower compared to high tides of up to +3,9 A.O.D.), it is not possible to discharge floodwaters at high tide. Drainage schemes are necessary to ensure the land is usable.
The general design principle of these present day schemes is that the runoff from the surrounding higher ground is carried across the lowland to sea outfalls via large, high level, embanked channels, These have sufficient capacity to store flood waters during tide-lock, The lowland network of ditches have been modified so that some of them flow to pumping stations at specific locations which can pump flood water up into the embanked channels. Other ditches are routed to enable water to be fed from the high level channels into the lowland to provide feed water for cattle during the summer