A MODEL TO PREDICT AND ASSESS THE EFFECTS OF GROUNDWATER WITHDRAWAL ON THE VEGETATION IN THE PLEISTOCENE AREAS OF THE NETHERLANDS

A model to predict the effects of groundwater withdrawal on the local flora is presented; it consists of five sub-models, each dealing with one factor or factor complex: (1) soil moisture supply, (2) soil aeration, (3) soil nitrogen availability, (4) "environmental dynamics", and (5) depth of open water. Plant species' response to changes in these factors is indicated in their moisture and nitrogen figures and in their classification with regard to environmental stability. Use of the model requires data on the soil and hydrology of a site, the species composition of the vegetation, and the changes in (ground-)water depth and moisture availability resulting from groundwater withdrawal. The end product is a list indicating the probability that the species at the studied site will disappear. This list can serve as a basis to assess the impact of groundwater withdrawal on the nature conservation value of the site. Sensitivity analysis of the model gave satisfactory results, but a first validation was hampered by unsuitable data. The model is used as an instrument to evaluate the interests of nature conservation in policy regarding water use and water management in The Netherlands. © 1990 Academic Press Limited.