FGR’01 – 3rd International Conference, Lisbon – Portugal 151 The impact of land-use changes on the groundwater in the Grote

A GIS based hydrological scenario modelling methodology has been set up to simulate the effects of land-use changes on groundwater recharge and discharge. GIS is used in handling the input and output data from the model and creating a common environment for the hydrological models. The effect of land use on the groundwater recharge is simulated with the WetSpass model, while the groundwater flow is simulated with a modified form of the MODFLOW model. Modelling results are verified by comparison with measured river discharges and groundwater heads. The occurrence and extend of discharge areas is verified by mapping phreatophytic vegetation in the field. Based on the simulation of the actual situation two different hydrological scenarios, a pre-development and a future scenario have been simulated for the Grote-Nete river basin, Belgium. Three approaches to represent the hydrological effects of land-use change in the future scenario simulation are discussed. The results identified the sensitivity and impact of changes in groundwater discharge amount and sizes of recharge and discharge areas