Increasing influence of evapotranspiration on prolonged water storage recovery in Germany

Central Europe, including Germany, has faced exceptional multi-year terrestrial water storage (TWS) deficits since 2018, negatively impacting various sectors such as forestry, energy production, and drinking water supply. Currently, the understanding of the recovery dynamics behind such extreme events is limited, which hampers accurate water management decisions. We used a simulation of the mesoscale hydrological model (mHM) over the last 257 years (1766–2022) to provide the first long-term perspective on the dynamics of the TWS deficit recovery in Germany. The results show that severe TWS deficits surpassing a peak deficit of −42 mm (−15 km ^3 ) exhibit large variability in recovery times (3–31 months). The 2018–2021 TWS deficit period was unprecedented in terms of recovery time (31 months), mean intensity and the associated negative 30-year TWS trend. In recent decades, we identified increased evapotranspiration ( E ) fluxes that have impacted TWS dynamics in Germany. Increased E flux anomalies contributed to prolonged TWS recovery, given that the TWS deficit did not quickly recover through above-average precipitation ( P ). An extreme TWS deficit similar to that in 2018 was recovered by above-average P within three months in the winter of 1947–1948. Our research contributes to an improved understanding of the dynamics and drivers of TWS deficit recovery.