Climate Change Impacts on Hydrology in the Upper James Watershed, Virginia

Abstract

Hydrological modeling of the Upper James Watershed (UJW), Virginia, is critical for predicting water availability, flood management, agriculture, ecosystem protection, and hydropower production under increasing climate change. The Hydrologic Engineering Center–Hydrologic Modeling System (HEC-HMS) is applied to evaluate climate change impacts on key hydrological components within the watershed. Future climate conditions were assessed for the near (NF: 2026–2050), mid (MF: 2051–2075), and far (FF: 2076–2100) periods using three Global Climate Models (GCMs) under Shared Socioeconomic Pathways SSP 2–4.5 and SSP 5–8.5. Climate data were bias-corrected using the Linear Scaling Method (LSM) and used to drive the HEC-HMS model. Results project annual precipitation reductions of 8.19% (SSP 2–4.5) and 14.63% (SSP 5–8.5) for 2026–2100 relative to the 1998–2022 baseline, with corresponding annual streamflow changes of a 4.16% increase and a 0.62% decrease, respectively. Key hydrological components, including infiltration, evapotranspiration, interception, surface runoff, and baseflow, are projected to decline across all future periods, with reductions ranging from 10.17% (NF) to 17.00% (FF) under SSP 2–4.5 and from 11.74% (NF) to 30.20% (FF) under SSP 5–8.5. These results highlight the need for improved reservoir operations, sustainable land-use practices, and enhanced flood and drought forecasting to mitigate climate impacts and support informed decision-making.