Author(s): Xinbao Zhang; Xiubin He; Anbang Wen; D. E. Walling; Mingyi Feng; Xiang Zou
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Keywords: Sediment source; Relative contribution; 137 Cs; 210 Pb; Hilly Sichuan Basin
Abstract: Double radionuclide tracers of 137 Cs and 210 Pb were used to investigate sediment sources in the Wujia Gully, a small catchment in the Hilly Sichuan Basin in 2002. Average 137 Cs and 210 Pb concentrations in the source soils of the steep forest slopes, gentle cultivated terraces and bare slopes were 7.15 Bq·kg -1 ±0.40 Bq·kg -1 and 162.01 Bq·kg -1 ±3.86 Bq·kg -1,4. 01 Bq·kg -1 ±0.31 Bq·kg -1 and 70.96 Bq·kg -1 ±2.65 Bq·kg -1, and 0 and 15.12 Bq·kg -1 ±1.22 Bq·kg -1, respectively, while those concentrations in the recently deposited sediments in the reservoir were 3.06 Bq·kg -1 ±0.23 Bq·kg -1 and 72.66 Bq·kg -1 ±1.61 Bq·kg -1, respectively. By using the mixing model, the relative sediment contributions from steep forest slopes, gentle cultivated terraces and bare slopes (including channel banks) were estimated to be 18%, 46% and 36%, respectively. Cultivated terraces and bare slopes (including channel banks) were the first and the second important sediment sources in catchment. Specific sediment yield in the catchment was 642 t·km -2 ·a -1 from the deposited sediment volume in the reservoir since 1956. Soil erosion rates for the forest slopes and cultivated terraces, which accounted for 2/3and 1/3 of the drainage area in the catchment, were estimated to be 173 t·km -2 ·a -1 and 886 t·km -2 ·a -1, respectively.
Year: 2004