INTRODUCTION OF A NEW GEOMORPHOMETRIC PARAMETER BASED ON TOPOGRAPHIC CROSS-SECTIONAL AMPLITUDE FOR DELINEATING THE EXTENT OF RIPARIAN AREAS IN HEADWATER CATCHMENTS

Headwater catchments in the Southern Appalachians are understudied and relatively little is known about the extent of functioning riparian areas in these catchments. A recent study from an ongoing research and water quality monitoring project in the headwaters of the Upper South Fork of the New River (USFNR) watershed has shown that land cover within a fixed distance of 100m of the stream is a strong predictor of water quality at the catchment outlet. Currently, the USFNR watershed project has sondes collecting measurements at the outlets of 7 USFNR subcatchments every 15 minutes (pH, temperature, specific conductance, and depth). In addition, monthly grab samples are collected at the outlets and analyzed for chloride, nitrate, and sulfate. This rich water quality data set makes the USFNR an ideal location to study factors influencing water quality in headwater catchments.

Elsewhere, other studies have shown that riparian areas can significantly alter the chemical signature of the shallow subsurface flow of hillslope water before it enters the stream. This buffering capacity has been shown to have a significant influence on instream water quality. To better assess the influence of riparian buffering capacity on water quality in the USFNR watershed, the location and extent of riparian areas must be mapped, ideally, with a method improving upon a linear distance measurement. Integral to mapping the extent of riparian areas is accurately determining the transition point from floodplain/riparian processes to hillslope processes. This study introduces and evaluates a new geomorphometric parameter based on topographic cross-sectional amplitude for the purposes of delineating riparian areas in the headwater catchments. This new parameter is defined as the distance between a curve created by a cross-sectional profile of elevation values perpendicular to a stream and a line extended from the lowest point on the profile to the highest point after the profile has been rotated by the angle Ө and reflected about the x-axis. The extent of riparian areas predicted by this new parameter was verified with fieldwork, and the hypothesis that this parameter accurately predicts the extent of headwater riparian areas was tested.