The Holderness Coast

The Holderness Coastline between Flamborough and Spurn Head in Yorkshire has one of the most rapidly eroding coastlines in Europe. Average rates of coastal retreat are around 1.8 metres a year. The causes of rapid erosion are:

·      Cliffs are made of weak, incoherent boulder clay deposited by Devensian ice.

·      Powerful destructive waves from the north-east, where the fetch extends for over 2,000 kilometres.

·      Longshore drift which transports sand and shingle, which might otherwise form beaches south to Spurn Head.

·      Thin, poorly developed beaches which provide little protection against wave attack. The lack of beaches along the coast is particularly significant. A wide, well developed beach absorbs wave energy, leaving little or no surplus energy for coastal erosion. On the Holderness coast, natural processes are unable to stop waves; and that erosion will continue until the coastal system establishes a new equilibrium.

·      The stable angle for clay is 10 – 15 degrees, but as the cliffs are much steeper than this, the coastline is prone to undercutting and slipping. The cliff retreat is caused by approximately 20% direct marine erosion, and 80% mass movement. The clay is very prone to sliding especially after periods of heavy rain.

·      Since Roman times, the sea has advanced 3 kilometres and 29 villages disappeared.

When areas such as Barmston and Mappleton are at risk from coastal erosion, a number of strategies can be implemented to reduce the risk.

6 houses in Mappleton have been lost in the last 50 years. In 1992, a rock groyne and armour block defences were constructed. Mappleton was chosen for protection mainly due to the route of the B1242 which passed through the village. It was calculated that it would cost less to construct coastal protection, rather than move the road, a vital link between the villages and towns along this stretch of coastline.

Erosion rates at Mappleton have been reduced. The road has been protected. However, for anyone living further south, the impact has been dramatic. Sue Earle at Great Cowden farm has seen her livelihood disappear into the sea due to accelerated erosion rates south of Mappleton. Longshore drift has been interrupted. Consequently, the beach below Great Cowden farm has been starved as sediment.

D.Drake 2008