Somerset Levels - Sea Defences

Sea Defences

The Somerset Levels consist of a coastal clay belt only slightly above mean sea level, with an inland peat belt at a lower level behind it. Thus, the Levels are at risk from both tidal and land-based flood waters. They were frequently flooded by the sea during high tides, a problem that was not resolved until the sea defences were enhanced in the early 20th century. In addition, the problems of high fresh water floods are aggravated by the unrestricted entry of the tide along the Parrett, which is the only river in the Levels and Moors that does not have a clyse on it. Discussions on whether a clyse is needed for the Parrett and whether it should be sited at Bridgwater or nearer the mouth of the river date back to 1939, at start of Second World War, and have not been resolved. The Environment Agency's current "Parrett Catchment Flood Management Plan", published December 2009, divides the Parrett catchment area into eight sub-areas, with the Somerset Levels and Moors falling into sub-area 6 and Bridgwater falling into sub-area 7. As part of the published flood risk assessments for both these sub-areas, it is recognised that: at a future date a tidal clyse may be needed on the Parrett; this causes a funding dilemma; and, geomorphology studies of the Parrett and the Tone are needed to help address many of the uncertainties associated with a tidal exclusion project.

During the great storm of 1703, waves came four feet (1.2 m) over the sea walls. The sea wall was again breached in 1799, filling the Axe valley with sea water. In 1872, another flood covered 7,000 acres (28 km2) and in 1919, 70,000 acres (283 km2) were inundated with sea water, poisoning the land for up to 7 years. Since 1990, the drainage board has been charged with looking at the rhynes, cleaning them out and keeping them clear, under the overall responsibility of the Environment Agency. With rising sea levels, the work required to maintain the sea defences is likely to become more expensive, and it has been proposed that two inland seas be created. Other studies have recommended maintaining the current defences for five years while undertaking further studies of available options.