RELATING VARIATIONS IN SOIL COMPOSITION TO CONCENTRATION-DISCHARGE RELATIONSHIPS IN A DISTURBED HEADWATER CATCHMENT

Past research showed differences in streamwater major ion concentrations between two tributaries in the Western Carolina University research watershed, Gribble Gap. Ion concentrations decreased with increasing discharge according to a power law relationship. Previous work also showed that ion concentrations in one tributary were significantly higher than the others. The purpose of this study was to further investigate the concentration-discharge relationships in the two tributaries and determine if those relationships are affected by variations in soils throughout the watershed. To do this, discharge was measured at a flume in the main Gribble Gap stream and by using a slug injection salt dilution method for the two tributaries. To characterize soil differences, soil pits were excavated along a transect across the watershed. Once a pit was open, major horizons were measured and characterized by their color, texture, and structure. Preliminary data showed there are distinct soil color and texture transitions across the watershed. Furthermore, initial observations suggest the one tributary has higher discharge and responds differently to precipitation and therefore may have a different concentration-discharge relationship than the other tributary. Initial findings suggest that the differences in ion concentrations between the streams are due to a combination of different soil characteristics and the resulting streamflow-generation flow paths.