GIS-based recharge estimation by coupling surface-subsurface water balances

A spatially distributed water balance model is developed to simulate tong-term average recharge depending on land cover, soil texture, topography and hydrometeorological parameters. The model simulates recharge iteratively connected to a groundwater model, such that the recharge estimate is also influenced by the groundwater depth and vice versa. Parameter estimation for the model is performed on the basis of literature values of water balance fluxes from mainly Belgium and The Netherlands. By graphical and non-linear baseflow separation for 17 catchments it is shown that recharge spatially varies considerably. The water balance model coupled to a regional groundwater model is applied and successfully tested on the 17 catchments. The application shows that the resulting recharge has a spatial complex pattern, depending to a large extend on the soil texture and land cover. Moreover, shallow groundwater levels in valleys cause negative recharge conditions as a result of evapotranspiration by abundant phreatophytic vegetation. GIS analysis shows how recharge strongly varies for different combinations of land cover and soil texture classes. The performed analysis provides a better insight into the sustenance and management of groundwater resources. (C) 2007 Elsevier B.V. All rights reserved.