29-3 Does Increasing Urbanization Lead to a Greater Urban Biogeochemical Signature? A Multidecadal Perspective of the Enoree River Basin, South Carolina

Session: Undergraduate Research, Part II (Posters)

Presenting Author:

Authors:

Abstract:

Urban streams have a distinct biogeochemical signature which often includes higher concentrations of ions such as nitrate, sodium, chloride, and calcium than in streams of nearby rural watersheds. Since the early 2000s, the Piedmont region around Greenville, South Carolina, has been one of the most rapidly urbanizing regions in the United States. Piedmont streams are characterized by low conductivity and are sensitive to altered biogeochemical cycles. The goal of our study was to determine if increased urban land cover between 1999 and 2025 resulted in increased stream solute concentrations in tributaries of the Enoree River. During June-July 2025, we collected water samples under baseflow conditions from 23 stream locations draining watersheds from 0.6 to 47 km² with land covers ranging from mostly forested to mostly urbanized. These locations had been sampled previously in the summers of 1999 and 2000. Between 2001 and 2019, based on NLCD data, total developed land cover increased by up to 23% and impervious surface cover increased up to 15% in these watersheds largely at the expense of forest cover. Nitrate concentrations correlated positively with total developed land cover and percent impervious surface cover in both time periods. Chloride concentrations correlated positively to urban land cover only in 2025. However, changes in solute concentrations from 1999-2000 to 2025 did not correlate significantly with changes in land cover over that time. The only exception was chloride concentrations, which increased significantly with increase in urban land cover. Our results suggest, overall, the expansion of urban land cover was insufficient to cause increased stream solute concentrations. Factors such as riparian zone function, stormwater retention basins, integrity of sewage infrastructure, or distance of developed land from stream channels may have reduced the impact of expanding urban land cover. Further research is needed to ascertain the threshold of urban land cover required to increase stream solute concentrations in this region.

Geological Society of America Abstracts with Programs. Vol. 58, No. 1, 2026

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