Impacts of Land Cover Change on the Spatial Distribution of Nonpoint Source Pollution Based on SWAT Model

Nonpoint source (NPS) pollution is a pressing issue worldwide, especially in the Chesapeake Bay, where sediment, nitrogen (N), and phosphorus (P) are most critical water quality concerns. Despite significant efforts by federal, state, local governments, improvement has been limited. Investigating spatial distribution of NPS hotspots can help understand pollutant output guide control measures. We hypothesize that as land cover changes from natural (e.g., forestland) agricultural to suburban ultra-urban, areas becomes increasingly spatially uniform. To test this hypothesis, we analyzed three real watersheds with varying (Greensboro watershed for agriculture, Watts Branch suburban, Watershed 263 ultra-urban) synthetic developed based on watershed, which ranged forested ultra-urban but had same soil, slope, weather conditions. The Soil Water Assessment Tool (SWAT) was selected phenomenological model analysis, SWAT-CUP used calibration validation. hydrologic responses were simulated over ten years (1993–2002 or 2002–2011), validation results indicated SWAT could properly predict export runoff target constituents (sediment, total nitrogen, phosphorus). showed outputs uniform agriculture across watersheds. This research suggests function major category study watersheds, strategies should be adapted accordingly. If distributed unevenly hotspot disproportionate amount require more targeted intensive Conversely, if need widespread encompass larger area.