Present and future water scarcity in Switzerland: Potential for alleviation through reservoirs and lakes

Manuela I Brunner; Astrid Björnsen Gurung; Massimiliano Zappa; Harry Zekollari; Daniel Farinotti; Manfred Stähli

doi:10.1016/j.scitotenv.2019.02.169

Present and future water scarcity in Switzerland: Potential for alleviation through reservoirs and lakes

Sci Total Environ. 2019 May 20:666:1033-1047. doi: 10.1016/j.scitotenv.2019.02.169. Epub 2019 Feb 17.

Authors

Manuela I Brunner¹, Astrid Björnsen Gurung², Massimiliano Zappa², Harry Zekollari³, Daniel Farinotti³, Manfred Stähli²

Affiliations

¹ Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Zürcherstrasse 111, Birmensdorf ZH, Switzerland. Electronic address: manuela.brunner@wsl.ch.
² Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Zürcherstrasse 111, Birmensdorf ZH, Switzerland.
³ Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Zürcherstrasse 111, Birmensdorf ZH, Switzerland; Laboratory of Hydraulics, Hydrology and Glaciology (VAW), ETH Zürich, Zürich, Switzerland.

PMID: 30970470
DOI: 10.1016/j.scitotenv.2019.02.169

Abstract

In Alpine regions, future changes in glacier and snow cover are expected to change runoff regimes towards higher winter but lower summer discharge. The low summer discharge will coincide with the highest water demand for irrigation, and local and regional water shortages are expected to become more likely. One possible measure to adapt to these changes can be the extension of current uses of artificial reservoirs and natural lakes to the provision of water for the alleviation of water shortage. This study assesses the potential of reservoirs and natural lakes for the alleviation of water shortages in a nationwide analysis in Switzerland. To do so, we estimated water supply and demand under current and future conditions both under normal and extreme runoff regimes for 307 catchments. Water demand was assessed for various categories including drinking water, industrial use, artificial snow production, agriculture, ecological flow requirements, and hydropower production. The aggregated supply and demand estimates were used to derive water surplus/shortage estimates. These were then compared to the storage capacity of reservoirs and natural lakes within a catchment to determine the potential for alleviating summer water scarcity. Our results show that water shortage is expected mainly in the lowland region north of the Alps, and less in the Alps. In this lowland region, the potential of natural lakes for alleviating water scarcity is high. This potential is lower in the Alps where it is expected to increase or decrease under future conditions depending on the region of interest. Catchments with a high storage capacity can potentially contribute to the alleviation of water shortage downstream. We conclude that a spatial mismatch between water scarcity and storage availability exists since water stored in reservoirs on the southern side of the Alps is often not available for the use on the northern side.

Keywords: Climate change; Multi-purpose reservoirs; PREVAH model; Storage capacity; Water demand; Water shortage.