Shingle State 1, Erosional

Definition: An erosional beach is characterised by having an overall deficit in the sediment supply and a tendency to move landwards and/or breach

This state is represented in those situations where a beach is more or less constantly eroding/moving, or at least the time between erosion episodes is too short for anything other than annual vegetation to grow. These sites are characterised by having a dynamic beach, which is moving alongshore or landward under the influence of the sea. They may have beaches with low cliffs or steep shelving shores and high ridge crests. The precise form at each site depends on the balance between:

• sediment availability [there is usually have a deficit of shingle i.e. more is lost through sediment transport out of the system than is gained];
• relative sea level;
• wave action, especially during exposure to storms.

The typical form shown opposite is present on many shingle beaches throughout the UK, but especially on the south coast. The value of this state lies in the potential it provides for restoring structure and function to what if often a 'fossilised' habitat. These type of beaches are characterised by the presence of coastal defence structures including groynes and breakwaters designed to hold the shingle in place.

Caption: The shingle ridge at Porlock, Somerset. This ridge is attempting to move landward (roll-over) and is regularly disturbed by storm waves hence the absence of vegetation. It has been maintained in the past by the installation of groynes and periodic bulldozing to raise the crest height, which has also restricted the opportunities for plant establishment.

Comment: Note that the long term sustainability of protecting eroding shingle beaches on dynamic shorelines is one of the key issues being addressed by the Living with the Seas Project (http://www.english-nature.org.uk/livingwiththesea/) CHaMP for North Norfolk (Cley, Annex 07) and at Dungeness (Annex 05).

Caveat: Not all eroding beaches fall into this state. Beaches that are attempting to 'roll-over' landward but are in a state of dynamic equilibrium in relation to sediment availability are included in the State 2 Accretional category.