Changing climate drives future streamflow declines and challenges in meeting water demand across the southwestern United States

• DOI: 10.1016/j.hydroa.2021.100074
• Publication Date: 2021-01-27T07:00:05Z
• Authors: Olivia L. Miller; Annie L. Putman; Jay Alder; Matthew Miller; Daniel K. Jones; Daniel R. Wise
• Keywords: Representative Concentration Pathways

Society and the environment in arid southwestern United States depend on reliable water availability, yet current use outpaces supply. Water demand is projected to grow future climate change expected reduce To adapt, managers need robust estimates of regional supply support management decisions. address this need, we estimate streamflow seven resource regions U.S. using a new SPAtially Referenced Regressions On Watershed attributes (SPARROW) model. We present projections corresponding input data from models two greenhouse gas Representative Concentration Pathways (RCP4.5 8.5) for three, thirty-year intervals centered 2030s, 2050s, 2080s, historical thirty year interval 1990s. Across regions, about half RCP4.5 (51%) thirds RCP8.5 (67%) indicate decreases 2080s relative period. Models project maximum 36–80% all periods RCPs streamflow, up 20–45% at sites along Colorado River used measuring compliance with interstate international agreements. Headwaters are experience greatest declines, substantial downstream implications. Among these estimates, streamflows forced tend be lower than those RCP4.5. Not models, times, widespread declines. The most ubiquitous increases occur 2030s under Later time enhanced forcings smaller increase accumulated streamflows, suggesting that limiting or reducing concentrations could availability. Although some possible promising, modest spatially limited later still unlikely sufficient meet demand. These results inform likelihood agreement compliance, developing strategies balance