Understanding how climate change is affecting groundwater Climate change is likely to influence the temperature of groundwater, thereby affecting many biological and chemical aspects of groundwater quality. The influence of climate and climate change on groundwater temperature is analysed using historical data from the recent past.

Lay summary
Groundwater is especially important in Switzerland as it supplies 80% of the country's drinking water. We know that climate change is influencing water quality in lakes and rivers, but we have very little information on its effect on groundwater quality. Comparison of fluctuations in regional climate in the recent past with fluctuations in groundwater temperature helps us to understand how climate change might affect groundwater. Groundwater temperature is especially important in this context because many biological and chemical aspects of groundwater quality are temperature-dependent.

Aim and methods
The aim of this project is to find out how regional climate change, which is occurring especially rapidly in the European Alpine region, is influencing groundwater variables like temperature, water level and oxygen concentration. Long-term historical data from groundwater in Switzerland will be collected and analysed using the statistical methods of time-series analysis. This will allow the extent to which different types of groundwater in Switzerland are changing in response to climate change to be determined.

Very little information is available nationally or internationally that shows how different types of groundwater respond to climate change. It is important to know this, however, because future management decisions with respect to our water resources must take into account the impact of climate change.