Urban Growth and Water Quality: Applying GIS to identify vulnerable areas in the Sandhills region of NC

Abstract

The Sandhills region, located in central North Carolina, is expected to experience dramatic population growth in the next 5 years. Population growth triggers urbanization, which may result in impairment of local water bodies. This study applied GIS analysis and the Environmental Protection Agency’s Analytical Tools Interface for Landscape Assessments (ATtILA) to investigate the effects of alternative patterns of future urban development on water quality in the Sandhills region. GIS tools, along with considerations for population growth and future planned roads, were used to develop two scenarios for future land use: “Less Sprawl” and “More Sprawl.” The “Less Sprawl” refers to a case of land cover associated with high housing density, 9 units per acre, and new developments occurring near existing urban developments and major roads. The “More Sprawl” scenario is represented by lower housing densities and more dispersed new developments. Then ATtILA was applied to model relative changes for nitrogen and phosphorus area loadings in 12-digit hydrologic units between each scenario. Finally, the site ranking was developed to identify areas of the highest concern. The ranking was based on the projected level of impact of urban growth on the water quality and the amount of conservation areas in each hydrologic unit.