Human Water Use Impacts on the Strength of the Continental Sink for Atmospheric Water. Issue 9 (12th May 2018)

• Record Type: Journal Article
• Authors: Keune, Jessica; Sulis, Mauro; Kollet, Stefan; Siebert, Stefan; Wada, Yoshihide
• Is Part Of: Geophysical research letters. Volume 45:Issue 9(2018)
• Page Start: 4068
• Page End: 4076
• Publication Date: 2018-05-12
• Subjects: human water use -- groundwater‐to‐atmosphere feedback -- continental sink -- groundwater dynamics -- groundwater abstraction -- sustainability; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2018GL077621
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: In the hydrologic cycle, continental landmasses constitute a sink for atmospheric moisture as annual terrestrial precipitation commonly exceeds evapotranspiration. Simultaneously, humans intervene in the hydrologic cycle and pump groundwater to sustain, for example, drinking water and food production. Here we use a coupled groundwater‐to‐atmosphere modeling platform, set up over the European continent, to study the influence of groundwater pumping and irrigation on the net atmospheric moisture import of the continental landmasses, which defines the strength of the continental sink. Water use scenarios are constructed to account for uncertainties of atmospheric feedback during the heatwave year 2003. We find that human water use induces groundwater‐to‐atmosphere feedback, which potentially weaken the continental sink over arid watersheds in southern Europe. This feedback is linked to groundwater storage, which suggests that atmospheric feedbacks to human water use may contribute to drying of watersheds, thereby raising water resources and socio‐economic concerns beyond local sustainability considerations. Plain Language Summary: In the global water cycle, the land receives more water through precipitation than it loses through evaporation and transpiration from plants over long time periods, leading to continental runoff of the continental river systems. Especially during dry periods, humans intervene in this natural hydrologic cycle by pumping groundwater and irrigation for agriculture to maintain drinking water and food supply. The impact of this human intervention on the water cycle including the atmosphere is not yet fully understood. Previous studies neglect the full feedback pathway from the bedrock to the atmosphere, thereby ignoring the fact that human water use may influence precipitation, which can in turn affect water resources. In this study, we use a modeling system that simulates the full terrestrial water cycle by incorporating groundwater dynamics in a regional climate model. We analyze how human water use affects the balance between precipitation and evaporation during the heatwave in 2003 over Europe, and we find that these changes are the main driver for drying of watersheds in southern Europe. These results suggest that human water use has impacts beyond the local scale via atmospheric processes, which is not yet considered in climate change and water resource assessment studies. Key Points: Human water use alters the continental sink for atmospheric water across watersheds Atmospheric feedbacks induced by human water use contribute to drying at the watershed scale over Europe Integrated modeling systems are required to quantify anthropogenic impacts on the water cycle through groundwater‐to‐atmosphere feedbacks