ESTIMATING SEDIMENT YIELD IN THE SOUTHERN APPALACHIANS USING

Abstract: We measured and modeled sediment yield over two months on five watersheds in the southern Appalachian Mountains of North Carolina. These watersheds contained first and second-order streams and are primarily forested, but span the development gradient common in this region, with up to 10 percent in suburban and transitional development and up to 27 % low-intensity agriculture. Sediment yield was measured using automated pumped samplers, continuous depth measurements, and gravimetric analysis. Sediment yield was predicted using WCS-SED for the coincident period employing fine and medium-resolution elevation, soils, and land use data. Mean sediment yield varied from 0.025 to 0.344 t/ha/yr and was strongly related to the proportion of non-forest area in the watershed. Sediment yield was not related to road density within the watershed or in near-stream areas. Predicted sediment yield was several times higher than observed sediment yield on four of five watersheds, with the most agriculturally developed watershed serving as the exception. Sediment yield was high over the plausible range of USLE land use and cropping factors that underlie the sediment yield predictions