DROUGHT CH: Early recognition of critical drought conditions in Switzerland - coping with shortages in soil moisture, groundwater and runoff

Background

According to climate change scenarios, drought risk will significantly increase in Switzerland in the coming decades. The drought and heat wave of 2003 demonstrated the severe consequences of such events and the lack of preparation of Switzerland. Consequences for nature and society include impacts on water resources, water supply, agriculture, energy production, building infrastructure and ecosystems. As droughts can enhance the severity of heat waves, they also impact human health.

Aims of the project

The project aimed at a better understanding and evaluation of drought risks in Switzerland. The project integrated natural and social science components: On the one hand, we characterised drought effects on ecosystems, soils and river systems by means of observations as well as hydrological and climate models. On the other hand, we evaluated costs and impacts associated with droughts and the potential benefits associated with their prediction. This analysis enabled us to investigate appropriate approaches for the prediction and early warning of droughts. Together with different stakeholders, we developed a first prototype of a virtual information platform for droughts.

Work Packages

In the research unit Economics and Social Sciences we worked on two work packages out of seven.

• Work package 1: "Critical drought and low-flow indicators for different water users". The main objective was to assess the specific needs of water user groups with regard to an early recognition system. We identified drought and low-flow indicators that are important from the point of view of the user groups and ensure that the development of the information platform meets the needs of the anticipated users.

• Work package 5: "Operational hydrological modelling and determination of snow water resources". In this work package we developed new operational forecast instruments for low flow and snow water resources in Switzerland. To this end we used the numerical model PREVAH driven with observed and modeled meteorological variables (COSMOLEPS, ECMWF EPS). A novel step was to assimilate the actual distribution of snow water equivalent of the alps on a daily basis allowing for issuing long-term predictions of snowmelt-fed reservoirs and streams.
• Work package 6: "Economic benefit of an early warning system of drought and low flow". This work package investigated the type and amplitude of potential impacts of drought and low flow, the needs and benefits regarding early warning systems and the requested attributes of such systems (e.g. lead time). We analysed how water user groups have so far coped with drought and low flow conditions and what would be the impacts of different scenarios of drought and low flow and what could be the contribution of a warning system to mitigate the potential damages. This helps to roughly estimate avoidable damage costs and the contribution of early warning systems to damage mitigation. Finally, we investigated different financing modes for early warning systems.
• Work package 7: "Development of an information platform for the early recognition of drought". Based on the scientific basis of the other work packages a prototype of an internet-based information platform for the early recognition of drought in Switzerland has been developed. The aim of this information platform was to provide an integral information on actual or imminent water shortage in Switzerland. On June 1 2014, we started to run a test operation - with the support of the Federal Office of the Environment and MeteoSwiss. This will allow us to gain experience with such a drought-specific information platform and to assess its potential benefit.