Sediment Fingerprinting for Calibrating a Soil Erosion and Sediment-Yield Model in Mixed Land-Use Watersheds

摘要

This research estimates sediment yield contributed from surface mining soils, stream banks, and forest soils using sediment fingerprinting with isotope tracers coupled with soil erosion and sediment yield modeling in mixed land use watersheds. New δ~(13)C and δ~(15)N tracer results from sediment sources and transported sediments are collected and explained; sediment fingerprinting, including uncertainty analyses, is performed; and soil erosion and sediment yield modeling is applied through calibration with sediment fingerprinting as well as sediment concentration measurements. The δ~(13)C and δ~(15)N tracers successfully separated the forest, reclaimed mine, and stream bank sources in Island Branch and Whitaker Branch watersheds located in the Appalachian region of Kentucky, and the results expand the literature database for the usefulness of δ~(13)C and δ~(15)N tracers to separate end-member sources. A significant difference was measured for the values of δ~(13)C and δ~(15)N of the forest sediment source when comparing data results collected in 2007 and 2009/2010, highlighting the nonconstant nature of the source. The results from the sediment fingerprinting allowed for further calibration of the transport capacity coefficient, sediment delivery ratio for reclaimed mining soils, and stream bank erosion parameters. Sediment yield from reclaimed surface mining sites showed a decrease over time including 4.4, 2.1, and 0.8 t • year~(-1) • ha~(-1) for 1 1/2, 4, and 6 1/2, respectively, years after mining. A severe ice storm and rainstorms increased forest sediment production by 3.5 times from 2007 to 2009/2010, and sediment yield increased from 0.08 to 0.29 t • year~(-1) • ha~(-1). Change in the stream bank sediment yield over time was not pronounced. Whitaker Branch bank sediment production was five times higher than Island Branch, which was attributable to the larger susceptible bank area and driving logging trucks across the stream. It is expected that soil erosion and sediment yield modeling in mixed land use watersheds will be coupled with sediment fingerprinting in future studies.