Keywords:
artificial dunes
eolian activity
forestry
urbanisation
Location: France, Aquitaine coast, Cap-Ferret
Cap-Ferret
The Aquitaine coast was characterised by mobile long ridges
of barchan type dunes. In the 18th century, fore-dunes did not
exist because of strong onshore winds removing more sand than
vegetation was able to trap. Cap-Ferret is the extreme south of
the sand bar wich closes the Arcachon Basin. Mobile dunes
were stabilised with trees wich later became of great economic
value. To protect the forest from inblowing sand, an artificial
dune acting as a rampart was created in the first half of the
19th century. The artificial dune started to move inland threatening
the forest it is supposed to protect. Marine erosion is severe
on the Aquitaine coast because of the negative sand budget and
because urbanisation leads to the degradation of the vegetation
cover. Sand has become mobile again at the beginning of the 19th
century when dune ownership was privately owned again. Vegetation
disappeared due to the lack of maintainence and the blowing wind
resulted in tongues of sand towards the forest.
Management
The Conservatoire du Littoral, a state agency, buys coastal sites
to protect them from the threat of urbanisation. Since the policy
of the Conservatoire is to avoid an artificialisation of the environment,
sand movements are accepted when they result from natural phenomena.
Restoration activities started in 1994 and aimed at controlling
wind processes by reinstatement of plant cover to stop the advancing
sand from threatening the urban area. The restored area is protected
from public access by footpaths, information panels and fencing.
Restoration activities
Prior to the restoration an ecodynamic mapping was carried out
by geographers. Then first 100000 m³ of sand was removed
from the houses to the seaward side. Wind breaks were placed to
repair deflation hollows and high deflation areas were covered
with branches to stop the sand from being blown away. The branches
provided a supply of organic matter by their slow decompostion.
This had the disadvantage of introducing alien species.
Results
In the sanded up area the situation is now stabilised. The succes
of the operation is in part due to the temporary respite in marine
erosion in combination with the arrival of a sand wave in this
sector. On the long term, the coast is retreating and sand will
remain a threat to urbanised areas.
References
- Paskoff, P., Dune management on the Atlantic coast of France
: a case study, in : forthcoming proceedings of Southport conference,
1998
