A key water quality indicator for both ecosystem and human water needs is river temperature, which is expected to change as climate warms. River temperature are highly controlled by local upstream catchment processes. Therefore, when studying influencing factors on river temperatures, it is desirable to use local-scale forcing. Yet, climate change is a global phenomenon, usually studied with Global Circulation Models (GCMs), which sometimes are coupled to Regional Climate Models (RCMs), through the use of Representative Concentration Pathway (RCP) climate scenarios. This coupling results in increased spatial resolution of the forcing, however local biases are still a problem for their use in local hydrological analyses, especially in mountainous regions.

In this project, locally downscaled projections of future air temperatures and streamflow are used to improve projections of future river temperatures in Switzerland. As climate forcing for two semi-deterministic water temperature models (air2stream & air2water) 9 GCMs coupled to 8 RCMs, 3 RCP scenarios, and projections of future river flow from 4 different streamflow models, are used.