Department Surface Waters - Research and Management

Evolution of stream and lake water temperatures under climate change

This project addresses the spatio-temporal evolution of water temperature in Swiss streams and natural lakes. Water temperature is one of the key variables influencing water quality and the state of aquatic (riverine and benthic) habitat and is therefore a link between hydrology/limnology and aquatic ecology. The principal objectives are:

• Numerical modeling of the thermodynamics of coupled stream-lake-stream systems considering climate forcing and discharge conditions.
• Quantification of climate change impacts on surface waters in Switzerland and identification of particularly vulnerable systems.
• Exploring possible adaptation strategies to mitigate the consequences of climate change, in particular atmospheric warming and decreasing summer precipitation resulting in more frequent low flow conditions in Swiss rivers despite the rapid melting of the snow cover and the alpine glaciers.

The project applies the model StreamFlow for the simulation of stream temperatures, and 1D or 3D models for the modeling of lake thermodynamics. Coupling of these models is planned to run various climate change scenarios based on the new CH2018 climate change scenarios of MeteoSwiss. More specifically, the principal objectives require

• improved simulation of stream temperatures after targeted model development,
• a more comprehensive understanding and quantification of coupled stream and lake temperature evolution in a changing climate,
• and identifying reliable and representative sites where to routinely measure lake temperature as an essential climate indicator.