What are the Drivers of River Water Temperature Below a Large Dam?
Abstract
Water temperature is a fundamental metric in rivers, controlling the rate of many aquatic processes. Large reservoirs can fundamentally alter downstream water temperatures, and dams are often operated to protect thermal regimes of downstream ecosystems. In this study we modeled water temperature dynamics in a large regulated river (Sacramento River, CA) to better understand how thermal flux, and ultimately river temperature, responded to different physical drivers. Specifically, we used global sensitivity analysis to identify the dominant physical drivers of temperature in the Sacramento River and explored how these drivers varied over space and time. We also sought to better understand the relationship between upstream boundary conditions (dam discharge temperature and volume) and under what conditions downstream water temperature responded more to perturbations of either of these two inputs. The physical drivers that influenced downstream temperature the most were dam discharge temperature, air temperature, and solar radiation, with dam discharge temperature being the primary controlling factor in upstream reaches and air temperature in downstream reaches. When isolating the effect of boundary conditions on downstream river water temperature, we observed that downstream temperatures often responded more to changes in dam discharge temperature compared to discharge volume. Understanding spatial and temporal extents of drivers of water temperature and the relative importance of these factors is critical when managing for river water temperature.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.H23K2050D
- Keywords:
-
- 1807 Climate impacts;
- HYDROLOGY;
- 1813 Eco-hydrology;
- HYDROLOGY;
- 1847 Modeling;
- HYDROLOGY;
- 1880 Water management;
- HYDROLOGY