The Influence of Impervious Surface Location on Water Quality in the Headwaters of the Southern Appalachian Mountains

Determining where critical areas in watersheds exist, and how land cover in these critical areas influence water quality is vital. Impervious land cover has been shown to have a negative influence on water quality; however, the influence of impervious surface location within individual watersheds is poorly understood. This study examined the effects of impervious surfaces on water quality in 23 headwaters catchments in the Southern Appalachian Mountains of Western North Carolina. An effective method for generating impervious surface classifications from aerial photography is presented. Using these impervious surface classifications, the influence of impervious surface position was examined. Additionally, using a functional definition of a riparian area, this study presents a methodology for delineating potential riparian zones from adjacent hillslopes along Southern Appalachian headwater streams. Impervious surface percentages were correlated with water quality (specific conductance) at the watershed outlet. The results indicate that impervious surface in potential riparian zones and low-order streams (i.e., less than 3rd order) are dominant controls of specific conductance measured at the watershed outlet.