title: Climatic and anthropogenic changes in Western Switzerland: Impacts on water stress.
abstract: Recent observed hydro-climatic changes in mountainous areas are of concern as they may directly affect capacity to fulfill water needs. The canton of Vaud in Western Switzerland is an example of such a region as it has experienced water shortage episodes during the past decade. Based on an integrated modeling framework, this study explores how hydro-climatic conditions and water needs could evolve in mountain environments and assesses their potential impacts on water stress by the 2060 horizon. Flows were simulated based on a daily semi-distributed hydrological model. Future changes were derived from Swiss climate scenarios based on two regional climate models. Regarding water needs, the authorities of the canton of Vaud provided a population growth scenario while irrigation and livestock trends followed a business-as-usual scenario. Currently, the canton of Vaud experiences moderate water stress from June to August, except in its Alpine area where no stress is noted. In the 2060 horizon, water needs could exceed 80% of the rivers' available resources in low- to mid-altitude environments in mid-summer. This arises from the combination of drier and warmer climate that leads to longer and more severe low flows, and increasing urban (+40%) and irrigation (+25%) water needs. Highlighting regional differences supports the development of sustainable development pathways to reduce water tensions. Based on a quantitative assessment, this study also calls for broader impact studies including water quality issues.
authors.affiliation: University of Lausanne, Institute of Geography and Sustainability, Building Géopolis, CH-1015 Lausanne, Switzerland. Electronic address: marianne.milano@unil.ch.
authors.forename: Marianne
authors.initials: M
authors.lastname: Milano
authors.affiliation: University of Lausanne, Institute of Geography and Sustainability, Building Géopolis, CH-1015 Lausanne, Switzerland. Electronic address: emmanuel.reynard@unil.ch.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Reynard
authors.affiliation: University of Bern, Institute of Geography, Hallerstrasse 12, CH-3012 Bern, Switzerland; Swedish Meteorological and Hydrological Institute, Folkborgsvägen 17, SE-601 76 Norrköping, Sweden. Electronic address: nina.koeplin@web.de.
authors.forename: Nina
authors.initials: N
authors.lastname: Köplin
authors.affiliation: University of Bern, Institute of Geography, Hallerstrasse 12, CH-3012 Bern, Switzerland. Electronic address: rolf.weingartner@giub.unibe.ch.
authors.forename: Rolf
authors.initials: R
authors.lastname: Weingartner
keywords: Anthropogenic changes; Climate scenarios; Mountain environment; Regional overview; Water stress; Western Switzerland