Agricultural water demand will rise due to climate change, but the expected amounts are unknown and depend on climatic conditions and cropping systems. Also, water resources are already overexploited, i.e. a rise in demand cannot be met in a sustainable manner. This study will quantify the water demand of different crops and assess the additional water amount required for irrigation. We analyze the actual situation by applying a process-based model, which is calibrated and validated by on-site measurements of meteorological boundary conditions and soil moisture. Crops are differentiated by crop-specific parameters. This yields location-specific estimates on agricultural potentials and required water for different crops, now and in the future. In the long run, we aim at extrapolating the local scale data to a regional scale where scenarios of e.g. mixed cropping systems can be explored.