Use Of GIS And Database with Distributed Modelling

Abstract

Integrated water management has developed into a complex task as a result of the conflicting claims made by competing groups of users on a limited resource - water. To obtain sound, realistic and economically feasible solutions for the increasing problems, the hydrologist needs to co-operate intensively with experts in the field of ecology, agriculture, urban planning and economics (Engelen and Kloosterman, to be published). They have to evaluate the solutions he proposes for all their possible impacts. Due to conflicting interests, the feasibility of an increasingly larger set of scenarios has to be examined and even the minor effects of these scenario’s have to be quantified. This can be achieved by simulating the hydrological measures implied by these scenarios. A trend can be observed to decrease the subjective elements in the simulation process and to give insight in the quality of the model in a stochastic context (Te Stroet, 1995). When many scenario’s have to be evaluated against each other, this becomes essential because a quantification of minimum and maximum effects prevents the hydrologist from making the wrong choices based on an erroneous model. Nowadays, the pure numerical results of a simulation are no longer the final products delivered by the hydrologist. The results have to be translated systematically into hydrological effects and subsequently into socially relevant quantities. As an example changes in agricultural production could be related to decreases in crop yields as a result of water shortness in summer periods and water excesses caused by insufficient drainage in winter periods. Also, the hydrologist should be able to provide a clear insight about the quality of the model to the interested parties.