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Sand dunes changing from State 1, Erosional - State 2, Open/Semi-mobile
Preventing sand movement, re-creating sand dunes and restoring sand dune stability
and with it vegetation have a long history. The presence of eroding (State
1) dunes has elicited a familiar response. In most instances some
form of remedial action was taken which included some or all of the following
'soft' approaches to dune stabilisation:
Where eroding fore dunes appear to threaten land with flooding as well as from
sand blow structures have been erected on the shoreline. These essentially engineering
'hard' structures include:
- Building sea walls, depositing 'protective' boulders
and other hard defences at or above high water;
- Shore protection with geofabrics;
- Groynes
on the shore;
- Gabions
on the shore;
Comment: It is debatable whether many of these approaches are really
necessary. The policies adopted in historical times and the evidence from sites
where grazing has stopped or been limited, suggest that simply removing the
vector responsible for promoting erosion can be effective in promoting stability
through the 'natural' process of succession.
Newly colonised beaches
and new
sand dunes can occur spontaneously if the conditions are appropriate.
| Guidance: Before embarking on a programme of protection a simple
question might be considered - "do I really need to actively intervene
to reduce sand movement or can I rely on 'natural' processes once the destabilising
vector is removed?" It is also the case that whilst stability can
be promoted this can, and often does, compromise other interests associated
with open dunes, see for example the cases of Braunton
Burrows, Newborough
Warren and Gullane
Bay. |
Comment: The techniques for stabilising sand dunes, should that be
the decision, are well tried and there are a number of useful publications including
the BTCV
Guide, Ranwell & Boar 1986,
and the SNH
Beach Erosion Guide.
References
Ranwell, D.S. & Boar, R.
1986.
Coast Dune Management Guide. Institute of Terrestrial Ecology, NERC, 105 pp.
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