Simulation of evapotranspiration and groundwater recharge in the Nete catchment accounting for different land cover types and for present and future climate conditions

This study stems from the need to characterise present and future groundwater recharge in the Nete catchment, situated in the Campine region of northern Belgium. This information is necessary to parameterise the groundwater model used for radionuclide transport in the context of the disposal of low and intermediate-level waste in Dessel. The major factors that could have an impact on future groundwater recharge were identified as changes in climate and land cover/use. This study uses an approach based on climatic analogue stations. Meteorological data from instrumental analogue stations are used to obtain weather time series. As far as land cover and land use are concerned, the approach adopted is to test the sensitivity of groundwater recharge to a complete conversion of the current Nete catchment land cover to a single hypothetical future land cover (meadow, crop, deciduous and coniferous forests). This document reports calculated groundwater recharge for current climate and land cover conditions. The average annual recharge for the Grote and Kleine Nete catchment is estimated at 391 mm/y. Then, a sensitivity analysis is performed to evaluate the impact of climate change or radical changes in land cover on the water balance.