Sediment Source Ascription of Forest Roads in the Upper Little Tennessee River Basin

Geochemical fingerprinting and the Water Erosion Prediction Project (WEPP) were used to estimate sediment production for catchments with, and without unpaved roads in the Upper Little Tennessee River Basin. Sediment source ascription is valuable because sediment is labeled as one of the most important non-point source pollutants affecting streams and water bodies in the southeastern United States (Simon et al 2002). The influx of fine sediment (<2 mm) in streams degrades biotic health in addition to transporting absorbed pollutants. The ability to trace the sources of fine sediment is a valuable contribution to watershed management, allowing sources to be mediated with better management practices. USDA Forest Service Roads represent surfaces of geologically fresh material, rich in minerals that are preserved in transport, distinguishable in sediment deposits, and the water column. Soil samples were collected from these deposits, and from sources of active erosion. A quantitative procedure was used to determine separability between classes and select optimal fingerprints for each watershed. Roads were distinguishable based on Calcium, Magnesium, Sodium, and Phosphorus. An end member mixing model based on the optimal fingerprints determined the proportion of each outlet sample produced by the respective classes (Collins et al 1997 & Miller et al 2005). A sediment budget provides an indication of annual sediment production and simulated data from WEPP provide at least partial support for the chemically ascribed data.