To support policy formulation for rehabilitation of the natural environment in the Western Mancha region in Spain, a planning support system was developed and applied. The system is based on a framework developed for planning and decision making, and includes three main components, namely, a water balance model of the groundwater basin, a planning model and an evaluation model. The water balance model, which makes use of GIS and remote sensing, simulates the average yearly recharge of the aquifer system in relation to the land use changes for average meteorological conditions, to help understand the current situation; the planning model, which makes use of mixed integer programming, simulates the reaction of farmers towards the changes in the present subsidy schemes and helps formulate a proper policy instruments; and finally the evaluation model, which makes use of multicriteria decision analysis to support the evaluation of developed policies and selection of attractive scenarios based on the identified criteria and the preferences/opinion of various decision makers.