Long-term drought effects on landscape water storage and recovery under contrasting landuses

Abstract

Recent extreme droughts in Europe have highlighted the urgent need to quantify their effects on ecohydrological fluxes (evapotranspiration, groundwater recharge) and water storage (mainly soil moisture) in the landscape. In response, we combined process-based (EcH2O-iso) and machine learning (NARX) models to estimate the enduring effects of long-term drought on water fluxes and storage and to project future short-term groundwater levels and recovery potential under various precipitation scenarios. The work was undertaken at the Demnitz Mill Creek (DMC), a 70 km2 mixed land use (arable crops and forestry) catchment in northern Germany. Our simulations indicated that the extreme drought years of 2018 and 2022 had the most marked impacts, leading to substantial declines in groundwater recharge (>40 %), evapotranspiration (up to 16 %) and soil moisture (up to 6 %). Simulations indicated that groundwater levels may not recover in the next 15 years if recent precipitation anomalies persist. These findings underscore the urgent requirement for enhancing resilience and promoting integrated strategies in managing land and water resources to optimise water retention in landscapes and to better respond to drought.