Cley Marshes - Threats

Threats

The reserve shelters behind a ridge of shingle that runs west from Weybourne along the Norfolk coast, before becoming a spit extending into the sea at Blakeney Point. Saltmarshes can develop behind the shingle, but the sea attacks the ridge and spit through tidal and storm action. The amount of shingle moved by a single storm can be "spectacular"; the spit has sometimes been breached, becoming an island for a time, and this may happen again. The northernmost part of nearby Blakeney was lost to the sea in the early Middle Ages, probably due to a storm.

The spit is moving towards the mainland at about 1 m per year, and for the last two hundred years maps have been accurate enough for the encroachment of the sea to be quantified. Blakeney Chapel, just west of the reserve, was 400 m (440 yd) from the sea in 1817, but this had reduced to 195 m (215 yd) by the end of the twentieth century. The landward movement of the shingle also means that the channel of the River Glaven becomes blocked increasingly often, leading to flooding of the reserve and Cley village. The Environment Agency considered a number of remedial options to protect these vulnerable areas, and a new route for the river to the south of its original line was completed in 2007 at a cost of about £1.5 million.

The sea defences at Cley were badly breached in 1742, 1897, 1953 and 1996, with smaller incursions in 1993 and 1998. The massive 1953 flood reached 8 km (4 mi) inland at Cley. Although the financial benefits from the recreational value of the reserve currently outweigh the costs of maintaining the sea defences, managed retreat is likely to be the long-term solution to rising sea levels at Cley and along much of the rest of the North Norfolk coast, and has already been implemented at other major sites including Titchwell Marsh. The important reedbeds at Cley will inevitably be lost due to increased saltwater flow into the marshes. To compensate, the Environment Agency and the Norfolk Wildlife Trust have been working since 2010 to make a new wetland near Hilgay. The 60-hectare (150-acre) Hilgay Wetland Creation Project is converting former farmland into a variety of wetland habitats by using banks, ditches and a lake to manage water levels. The Trust sees this as the first stage of a long-term plan to create a roughly 10,000-hectare (25,000-acre) Wissey Living Landscape.