Keywords:
mainland barrier dunes
hydrology
dune dynamics
drinking water recovery

Contact: DZH (Dunewater Company of South Holland), Department of Communication, telephone  +31 70 3577634

Location: Atlantic region, The Netherlands, Meijendel dune area

Meijendel and Berkheide dunes
The Meijendel and the Berkheide dunes are part of the great barrier dune system of the Dutch mainland coast, where many parabolic dunes formed  since about 1000 A.D. The dune areas are managed by the DZH. (Dunewater Company South Holland). The DZH provides drinking water but also takes responsibility for nature conservation and recreation. In 1874 the extraction of drinking water in the Meijendel dunes started. A canal was dug in the dunes to provide the city of The Hague of drinking water. Between 1880 and 1955 most of the natural dune slacks had dried out as a result of the lowering of the groundwatertable. With the increasing population, the amount of extracted water also increased thereby pumping up brackish water. In 1955 artificial infiltration of river water started and some dune valleys became wet again. For the production of drinking water an extensive infrastructure has been created. One of the features is a stretch of artificial lakes in the middle of the dune area for the infiltration of the drinking water.

Management
Main functions of the Meijendel dune area are nature conservation, drinking water recovery, coastal defence and recreation.  With the artificial recharge of the water table in the dunes, some dune slacks reappeared but  the typical vegetation was only established locally. The infiltration lakes are well spreaded over the area to maintain the natural dune relief.
In 1990 deep well drilling was introduced. River water is pumped into deeper soil layers at 40 to 60 m below sealevel  and extracted at the same deep level. This way the upper groundwatertable is hardly interrupted and wet slacks can develop under natural circumstances. The area where the hydrology is more or less natural must be enlarged, so that the characteristic dune forming processes like blowouts and wet slacks are encouraged. Regeneration measures in the Meijendel dune area included the removal of infiltration lakes and  the removal of a 25 cm thick sediment layer. The natural relief has recovered. The blowing of sand on a large scale is not permitted in the drinking water production zones.
The new management policy aims at small scale blowouts, and recovery of wet dune slacks by reducing the area where artificial infiltration is taking place by intensifying the production in a smaller area. Also the drinking water production and nature values are optimized.

Results
The first results are an increase in valuable plant species in wet dune slacks. The  dune morphology is more natural because of less restriction. Locally blowouts have developed. The natural hydrology is restored by regeneration projects.

References:

• Bakker, TH.W.M. & R.N.A. Kramer, Meijendel, a dune area in a densely populated part of the Netherlands, Coastline 1993-3, Coastline special (EUCC library code KJd).
• Bakker,TH.W.M., Fifty years of recreational planning in the Meijendel dunes near The Hague. A short story about cars and parking places, Coastal Dunes Recreation and Planning, Drees,J.M. (ed), EUCC Leiden, The Netherlands, 1997 (EUCC library code DRC 97)
• Jungerius, P.D. & van der Meulen, F., Aeolian dynamics in relation to vegetation in a blowout  complex in the Meijendel dunes, The Netherlands, Journal of Coastal Conservation 1997-3, pp 63-70, EUCC Leiden (EUCC library code KJC 97a)