title: Rain-on-snow events, floods and climate change in the Alps: Events may increase with warming up to 4°C and decrease thereafter.
abstract: This paper focuses on the influence of mountain rain-on-snow (ROS) events that can on occasion trigger major floods in alpine catchments. In order to assess the evolution of these events in a recent past, and the potential changes that could be experienced in a changing climate over coming decades, we have focused on a small catchment in north-eastern Switzerland, the Sitter, well-endowed with both climate and hydrological data. Observations show that there has been an increase in the number of rain-on-snow events since the early 1960s related to the rise in atmospheric temperatures. Results from a simple temperature-based snow model show that the number of ROS events could increase by close to 50% with temperatures 2-4°C warmer than today, before declining when temperatures go beyond 4°C. The likelihood of more ROS events suggests that the risks of flooding in a future climate may indeed get worse before they improve.
authors.affiliation: Institute for Environmental Sciences, Department of Physics, Department of Earth and Environmental Sciences, The University of Geneva, Switzerland.
authors.forename: Martin
authors.initials: M
authors.lastname: Beniston
authors.affiliation: Institute for Environmental Sciences, Department of Physics, Department of Earth and Environmental Sciences, The University of Geneva, Switzerland.
authors.forename: Markus
authors.initials: M
authors.lastname: Stoffel
keywords: Climate change; Floods; Snow