In about half of the Dutch coastal dunes, the former wet slacks have dried during the last 100 years. The purpose of this study was to find the causes of drying. A fall in watertable was the major cause. it was sometimes due to coastal erosion, sometimes to increase of evapotranspiration because of an increase in vegetation, especially the planting of coniferous trees, extraction of groundwater for mains of drinking water supply or drainage by ditches. Although slacks are drying out with a fall in watertable, the blowing out of sand to the watertable can produce new wet slacks. It is the combination of fall in watertable and the almost complete prevention of blow-outs, by planting of marram grass and other plants of trees, which make drying out a continuous process. In some dried areas, surface water from elsewhere is infiltrated for later recovery in behalf of drinking water supply. In such areas, dried slacks are flooded or channels have been dug by which open water has been produced on a considerable scale. Other dried slacks in such areas sometimes get wet again. Because of the unnatural fluctuations in watertable and the large supply of nutrients, the vegetation of such slacks is of a ruderal character and atypical of dunes.
|Qualification||Doctor of Philosophy|
|Award date||9 Oct 1981|
|Place of Publication||S.l.|
|Publication status||Published - 1981|
- aeolian sands
- water catchment