Watershed response of the Feather River Basin, California, United States of America to future climate changes

Watershed response of the Feather River Basin, California, USA, to future climate changes. Schematic summary of projected hydrologic changes in the Feather River Basin, California, USA, under future climate conditions. A calibrated SWAT+ model is driven by historical PRISM climate data (1991-2022) and future climate projections from four global climate models under RCP4.5 and RCP8.5 for 2070-2099. Results show substantial increases in n-day maximum streamflows relative to the 1986-2005 baseline, with annual peak flows increasing by approximately 62-161% under RCP4.5 and 58-266% under RCP8.5. The graphical abstract also highlights a decline in snowfall contribution to total precipitation and corresponding shifts in the timing and magnitude of peak water yield and runoff, indicating a transition toward more rainfall-dominated and more variable hydrologic conditions. Increasing mean annual temperatures under climate change are expected to reduce seasonal snowpack, increase evapotranspiration (ET), and alter summer baseflow in headwater watersheds worldwide. Strong regional variability in hydrologic responses highlights the need for catchment-scale, physically based models to assess future flood risk and water availability. This study examines climate-driven changes in the hydrologic response of the Upper Feather River watershed in the Sierra Nevada Mountains, California. Four priority climate models and two representative concentration pathways (RCP4.5 and RCP8.5) are used to evaluate future hydrologic responses of the watershed. Hydrologic processes are simulated using an objectively calibrated Soil and Water Assessment Tool Plus model for a historical baseline (1986–2005) and a future period 2070–2099), driven by observed and projected precipitation and temperature. Results indicate a declining contribution of snowfall to annual precipitation, with peak snowfall and water yield shifting 1–3 months earlier. Long-term annual maximum flows are projected to increase considerably, whereas low-flow responses are mixed, with both increases and decreases projected by the end of the century. These findings highlight the need for adaptive watershed management to enhance flood protection, water storage, and drought resilience. Future water resource planning should also account for one-to-three-month shifts in peak water yield and surface runoff due to changes in snowmelt timing and a lower snowfall-to-rainfall ratio under climate change. The modeling framework and insights are transferable to other snow-dominated headwater watersheds experiencing climate-driven change.