Abstract The Southeastern United States has been grappling with a multitude of water resource challenges, including increased sedimentation, diminished spring flow, and downstream eutrophication in various waterbodies across the region. These issues have raised concerns about the impact of land use and land cover (LULC) change on the overall health of watersheds. Despite the evident impacts of this change on the Southeast region, the intricate dynamics of LULC and their subsequent implications on water quality—particularly regarding total suspended solids (TSS), total nitrogen (TN), and total phosphorus (TP)—remain underexplored. This study aims to address this research gap by studying plausible changes in the hydrology and water quality across the Southeastern United States. By employing a blend of geospatial and time series analyses, and a calibrated-validated model—SPARROW—, our research delves into the sole impact of LULC changes on the hydrology and water quality Southeastern United States from 2012 to 2100 at the annual timescale. Future LULC is derived from existing projections by Integrated Climate and Land use Scenarios (ICLUS) and is cross walked to generate consistent LULC with the SPARROW classification. The SPARROW model results suggest that these LULC alterations lead to pronounced increases in surface runoff volume and loads of TSS,TN and TP. Our regional-scale modeling results provide insights about control actions that are needed to improve water quality under future LULC and the required coordination between state and local agencies to implement those actions.
