Potential Effects of Climate Change on Historical Streamflow and Water Temperature in the Southwestern United States

The Southwest is regarded as the hottest and driest region in the United States due to its characteristic desert climate. Global warming is further threatening this vulnerable area with increased temperatures and more severe droughts. The climate-driven change in streamflow can impact water supply, agriculture, power production, and water-dependent ecosystems. Thus, understanding the processes of historical streamflow variability is vital for water management practices under future climate change in the Southwest. Meanwhile, climate change in the American Southwest may drive up unprecedented warmer temperatures in streams. Rising stream temperature can have observable ecological and social effects. Water temperature directly affects plants and animals in freshwater regions. Specific industries are at significant risk from higher water temperature, such as the thermoelectric-power generation. Historical analysis and interpretation of the flow and temperature of streams will be critical to achieving social and environmental sustainability in the future. This study aims to investigate the spatial and temporal variability of streamflow and temperature in the Southwest. Furthermore, we assess the potential impacts of climate change on the region's historical river flow and temperature. Streamflow and water temperature data between 1990 and 2020 is available from the United States Geological Survey (USGS). We use both the Mann-Kendall and Pettitt tests to analyze the streamflow and water temperature variations. Finally, we also apply regression models to describe how streamflow and water temperature change according to their key driving factors.