Incorporating physically-based water temperature predictions into the National water model framework

While river water temperatures are a strong control on instream processes and aquatic ecosystems, monitoring networks for river water temperatures are often sparse. Despite recent advancements in water temperature modeling strategies, current models struggle to provide real-time and reach-specific predictions across broad spatial domains. We developed a physically-based water temperature model coupled to the National Water Model (NWM) to assess the potential for water temperature prediction to be incorporated into the NWM at the continental scale. Using model forcings and outputs from the NWM v2.1 retrospective, we evaluated the ability of four model configurations of increasing complexity to simulate hourly water temperatures in the forested headwaters of H.J. Andrews Experimental Forest, Oregon, USA during a six-week summer period. Our modeling framework, representing a first effort at pairing water temperature simulation with predictions from the NWM, suggests that the NWM can be leveraged to give insight into other water quality variables.
Keywords: Stream temperature; Water temperature; Mechanistic model; National water model; Energy balance