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Shingle - State 2, Accretional or semi-stable to State 1,
Erosional
A key issue when considering the restoration of coastal shingle lies in determining
the principle aims, and whether these are for sea defence purposes or nature
conservation and amenity. Whilst sea defence requirements seek to create stable
structures, there is an increasing recognition of the value of allowing the
natural dynamic to reassert itself. It has been argued that this can be a healing
force in degraded systems, especially where the surface shingle has been removed
or grossly disturbed (Doody 1992b).
Caption:
Allowing 'nature
to take its course'. A route to
restoring damaged and degraded shingle structures by allowing the natural dynamic
to become re-estabished.
Reversing the usual policy of protecting eroding beaches i.e. moving from the
paradigm of creating stability (moving from State
1 - State 2) and allowing
erosion to take place may be difficult to implement given the history
of intervention and attitudes towards 'giving up land to the sea'.
A number of scenarios where this approach has or could be implemented are identified:
- breach in a shingle bar with associated 'roll-back' and flooding of the
land behind. An example of this is Porlock
Weir on the Somerset coast;
- rollover of a shingle barrier onto terrestrial land (including grazing marsh),
tidal areas (including lagoons) or other coastal habitats, such as is occurring
at Slapton
on the south Devon coast;
- remobilisation of progressive ness formation which has been arrested by
artificial interference with its natural progression. An example is Dungeness
where erosion takes place from west to east as the ness attempts to move in
an easterly direction. Shingle
recycling is used to keep the beach in front of the power station
in place.
Comment: At the present time this is a little used and little understood
method of restoration. However, it is implicit in the Habitat
Action Plan for shingle that for some 'protected' areas the dynamics
within individual sites should be allowed to become re-established. Given the
major losses that have occurred at many of the larger sites, this approach could
generate considerable conservation benefit. Discussions are currently
taking place at Orfordness
and Cley-Salthouse
where consideration is being given to the cessation of beach nourishment.
References
Doody, J.P.
1992b.
Sea defence and nature conservation: threat or opportunity.
Journal of Aquatic Conservation, 2., 275-283.
Abstract...
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