Review: The influence of global change on Europe’s water cycle and groundwater recharge

Roughly a third of Europe’s water demand is satisfied by groundwater abstraction. Understanding how future changes in climate, weather, vegetation and land use will affect the transport of atmospheric water to the subsurface is critical for successful implementation of Europe’s Water Framework Directive and to maintain groundwater as a high-quality water resource. This paper summarizes the known drivers of trends and variations in groundwater recharge (precipitation, evapotranspiration and vegetation, land use) in Central Europe and how they have changed in recent decades. From past observations and future climate projections, the foreseeable consequences for groundwater recharge under a changing climate are discussed. The paper focuses on the complex role of soils and vegetation at the interface between atmosphere and groundwater, and addresses open questions and possible new directions for research. Summarizing the evidence, land use and land-use change have a large control on recharge, but the influence of climate change is increasingly recognized. Central Europe’s current transition from a temperate and relatively moist climate towards a more variable and Mediterranean-like climate may shift recharge patterns and increase the ratio of focused-to-diffusive recharge as precipitation patterns change and the frequency and intensity of climatic extremes (e.g., heavy rainfall, heatwaves, droughts, floods and wild fires) increase. However, uncertainty remains with regard to the dynamic response of Europe’s vegetation to climate change as well as to human modifications of the water cycle (e.g., through irrigation, forest management, artificial recharge or urbanization), which currently challenges model-based predictions of future recharge.