Climate induced changes in streamflow and water temperature in basins across the Atlantic Coast of the United States: An opportunity for nature-based regional management

Study region: Watersheds of the Atlantic Coast of the United States (ACUS) spanning a latitudinal range of 30.8 degrees N - 46.5 degrees N Study focus: This study assessed climate-induced changes (CMIP5-RCP 8.5) in projected stream -flow and water temperature estimates from individual SWAT watershed models across the ACUS territory by mid and end of the century. Seasonal and spatial trends as well as relationships between hydroclimatologic variables were analyzed to identify opportunities for regional implementation of water management strategies. New hydrological insights for the region: Changes in hydroclimatologic variables suggest spatial trends clearly differentiated by seasons. Northern and central watersheds are projected to experience the most dramatic changes in winter, summer, and spring streamflows (67 %,-25 %, and-24 %, respectively) and summer water temperature (6.2 degrees C), while southern watersheds presented the largest streamflow increase in fall (35 %), and water temperature changes greater than 3 degrees C for all seasons. These similarities and contrasts between ACUS watersheds' hydrologic responses provide an opportunity for regional management of climate induced impacts on water resources. Mitigation strategies such as regional conservation of forests and wetlands can alleviate water scarcity and extreme flow events occurring across the ACUS under the assumed emissions scenario. Results suggest that changes in seasonal air temperature and water temperature may be linearly related in watersheds at lower elevations with no snow influence; while streamflow, precipitation, and air temperature changes have complex non-linear relationships.