Assessing the potential of land use adaptation measures with eco-hydrological modelling to increase drought resilience.

Droughts jeopardize both ecosystem services and economic productivity within river basins - especially as their frequency and intensity are expected to increase as a result of climate change. One aim of climate adaptation measures is therefore to increase resilience through water retention in landscapes. In this contribution we aim at identifying suitable land use adaptation measures to increase drought resilience. To this end, the eco-hydrological model SWAT+ is used to analyze the hydrological response of different land use classes under drought conditions in the Lippe catchment in Germany. The model represents catchment specific land use information on crops and crop rotations, tree species and imperviousness of urban and industrial areas. Anthropogenic effects such as water exchange with the Western German transportation canal network and tile drainages are also modeled. The model is calibrated specifically with regard to representing low flow periods based on available discharge measurements from several gauges. The hydrologic response of different land use classes shows variations in evapotranspiration, soil moisture, ground water recharge as well as surface runoff and lateral flow during a drought period. This illustrates the potential of land use changes to improve drought resilience, by promoting land uses that increase water retention. Based on these findings, further research will be conducted to investigate the potential of combined land use measures to increase resilience on the catchment scale and under different climate and adaptation scenarios. In the future, the modeling approach will serve as a planning tool for river basin management of the Lippe and the potential to transfer these measures to other catchment areas will be determined in the KliMaWerk research project funded by the German Federal Ministry of Education and Research as part of the "Water Extreme Events" (WaX) research programme.