A process-based stream temperature modelling approach for mountain regions

- We apply hydrometeorological modelling coupled with process-based stream temperature modelling.
- The coupled modelling and field study approach helps advance our process understanding and enables better model development.
- We show how stream temperature can be simulated using spatial modelling and routinely collected meteorological and physiographic data.

SummaryMountain streams have thermal regimes that provide critical habitat for native aquatic organisms. However, understanding stream temperature response to environmental change in mountain regions is difficult because there is typically a lack of observations. This work aims to address this issue by coupling two process-based models to simulate stream temperature in a groundwater-dominated mountain catchment, Alberta, Canada, and using a reach-scale field study for model development and verification. Results suggest that it is possible to produce spatial simulations of hydrometeorological variables needed for process-based stream temperature modelling. Simulated stream energy budget estimates compare well with results from field-based studies, and errors in stream temperature simulations (RMSE < 1.6) are similar to other modelling studies, providing confidence in the methods developed. Model sensitivity analysis demonstrates the importance of incorporating meteorological, hydrological, and geomorphological controls on stream temperature in modelling studies. This study also demonstrates the current lack of process knowledge regarding in-stream ice cover and snowmelt effects on stream temperature, both of which can contribute substantially to stream thermal regimes. Future field-based and modelling studies should consider these processes in order to fully understand stream temperature response to environmental change.