Hydro-CH2018 research projects

One of the aims of Hydro-CH2018 is to improve understanding of the hydrological process and close some existing gaps in our knowledge of the impact of climate change on water resources in Switzerland. Various research projects have been launched and many Swiss research institutions are involved.

New hydrological scenarios for Switzerland

Based on the new CH2018 climate scenarios, this project is intended to update the hydrological scenarios for Switzerland. This will create the necessary baseline for adaptation measures and further impact studies. The new database will enable climate-induced changes in the hydrological process to be investigated and changes in the water cycle to be analysed and evaluated. Hydrological extremes and variability can be better simulated than with the old CH2011 scenarios. The projections, called transients (continuous in time), also give greater flexibility in the analyses.

Quantifying the contributions to discharge of snow and glacier melt

Schnee- und Gletscherschmelze
View from the Piz Tagliola to the Maighels valley and Maighels glacier (Anterior Rhine)
© Markus Weiler

Snow and glaciers respond very sensitively to temperature changes. This means that the proportions of discharge components from rain or snow and glacier melt along the Swiss rivers vary in the context of climate change. This has repercussions for the availability of water, particularly in periods of drought. This project therefore models the contributions to discharge from ice, snow and rain for the period 1970-2100 for all Swiss river basins on a daily basis. The purpose is not to determine the origins of individual water particles, but to quantify the extent to which discharge depends on the different components on specific days, i.e. the effect of inputs of rain and of snow and glacier melt. Contributions during extreme events and temporal variability and trends are of particular interest. This study is also embedded in the CHR (International Commission for the Hydrology of the Rhine Basin) project “Contributions to discharge of snow and glacier melt in the Rhine basin” which examines the whole of the Rhine basin down to Lobith on the Dutch border.

Evaluating future hydrological scenarios with stochastic climate data

In this research project the regional CH2018 climate scenarios (daily values, 12-km grid) are transformed to a 2-km grid and hourly resolution using a stochastic weather generator. The high-resolution climate data are then used for the hydrological modelling. This should reduce the uncertainty in the evaluation of future hydrological extremes, especially heavy precipitation and floods. The calculations are produced for three river basins, the Thur, Kleine Emme and Maggia, and are then compared with the results from other Hydro-CH2018 research projects.

FORHYCS-ICE: Combining the three environmental system models - hydrology, glaciers and forest - to improve future hydrological projections

Over recent decades many studies have examined the impact of climate change on individual environmental systems. The majority have used analysis of disciplinary (model) approaches focussing on a specific system (e.g. forest, water cycle, glaciers). This project combines three of these system models for the first time. The project is called FORHYCS-ICE and examines the impact of climate change simultaneously on hydrology, glaciers and the development and composition of the forests. The aim is to provide more consistent and interdisciplinary cross-system information.

AgriAdapt: Impact of climate and management changes on inputs and water resources in Bernese Seeland

Climate change increases the crop water requirement in agricultural production. At the same time, the availability of water in the summer months will fall due to less precipitation and increased evaporation. Agricultural climate adaptation by irrigation could exacerbate water use conflicts and possibly lead to overuse of the resource. This research project therefore focusses on the question of how far agricultural production can be maintained under the effects of climate change and what adaptations are necessary to achieve this (e.g. irrigation, crop selection). The impact of climate change and agricultural adaptation on groundwater resources is also examined. The intensively farmed Bernese Seeland has been chosen as the region to be studied. Irrigation from groundwater is an important factor in that area, though this specific water resource also has great relevance for the region’s drinking water.

Water balance and drought

The new CH2018 climate scenarios do not consider changes in future land use or irrigation. This raises the question of what the impact on the water cycle and water resources in Switzerland would be if those factors were included. With this in mind, the objective of this project is to provide information on the impact of various climate and land use scenarios on Swiss water resources. It will focus particularly on the sustainability of water use for irrigation.

Groundwater dynamics and storage in alpine catchments

The timing of snow melts in Alpine regions will shift due to climate change. This will have an impact on runoff, with rather less in spring and summer and more in winter. Groundwater may reduce the impact somewhat, depending on the region. Groundwater recharge will also alter due to climate change. The aim of the project is to study the relationship between the groundwater storage and the climate change induced difference in snow cover in alpine catchment areas and its impact on runoff behaviour. Above all, this should give a better understanding of the interaction between geomorphology, geology and hydrogeology, groundwater storage and runoff dynamics.

Potential of multi-purpose reservoirs to reduce the impact of summer drought

© Manfred Stähli, WSL

Natural and artificial lakes and storage and other reservoirs are already widely used to store water. They offer the potential to respond to local and regional water shortages, which are likely to occur more often in future as a result of climate change, population growth and more intensive farming. A large part of the glacier and snow melt which currently provides a significant proportion of the available water supply in a hot summer will be lost. The demands on use and the need for reservoirs and their multiple use will then grow. This research project examines the potential of multi-purpose reservoirs to reduce summer drought for the major hydrological regions of Switzerland and for selected case studies.

Impact on the water temperature

The temperatures of the Swiss surface waters have risen by 1-2°C in the last 30 years. Due to the forecast increase in air temperature, water temperatures will continue to rise – with consequences for aquatic ecosystems and water quality. This research project uses models to examine the impact of climate change on Swiss river and lake temperatures and their correlation. In a further phase, the impact on ecosystem services will be examined more closely (e.g. displacement of fish regions) and a baseline for water management measures will be created.

Changes in groundwater temperature

Grundwassertemperatur Basel
Basel-Stadt hydraulic and thermal groundwater regime (2010-2015 mean).
© Jannis Epting, Universität Basel

The impact of climate change on groundwater resources is not well known and differs for deposits in solid or unconsolidated rock, urban or rural locations and the prevailing groundwater recharge processes. To understand the relevant processes and specific location factors, it is necessary to identify the nature of the direct (cooling, heating) and indirect (climate changes) hydraulic and thermal boundary conditions. Based on selected representative Swiss unconsolidated rock groundwater deposits, this research project concentrates on characterising the actual current hydraulic and thermal conditions and obtaining key parameters (renewal rates, residence times, storage characteristics etc.). A comparison of these characteristic boundary conditions in different groundwater deposits forms the basis for deducing transferability to groundwater resources in general (typical situations).

Last modification 08.11.2018

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Hydrology Division

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