Impacts of climate change on groundwater recharge and water supply in southern Germany

Public water supply in southern Germany relies to a high degree on the usage of groundwater and spring water. Thus, knowledge about the development of the soil water balance and especially groundwater recharge is important. Within the cooperation project KLIWA (Climate Change and Consequences for Water Management), the development of the soil water balance and groundwater recharge from precipitation are simulated from 1951 until 2019, applying the soil water balance model GWN-BW. An increase in the annual mean temperature in southern Germany since the late 1980s is apparent. The amount of precipitation has decreased in the recent past, thus reducing groundwater recharge by precipitation. Simultaneously, an increase of the drought index (number of days with soil water content < 30% of the available water capacity) is visible. An increase in frequency and duration of drought periods challenges water management and requires early action recommendations, e.g. based on the here presented "dry weather supply", to diminish resource conflicts.