三峡库区菱角塘小流域土壤侵蚀量和泥沙输移比研究

Sediment delivery ratio and soil erosion quantity on Lingjiaopond small watershed in the Three Gorges Reservoir Region

泥沙输移比对正确评价水土保持减沙效益具有重要意义。以三峡库区菱角塘小流域为研究对象,在应用137Cs示踪技术测定塘库和谷地泥沙沉积量的基础上,计算了小流域1963-2013年土壤侵蚀量和泥沙输移比,并讨论了采用不同侵蚀量算法计算的小流域泥沙输移比差异特征。结果表明：菱角塘小流域塘库和谷地水稻田泥沙沉积量分别为1 835.75 t和3 781.80 t;基于本文的测定法、常用的插值法和模型法计算的小流域土壤侵蚀量分别为5 821.52 t、7 240.50 t和10 504.25 t;不同侵蚀量算法计算的菱角塘小流域泥沙输移比差异明显。应用本文提出的137Cs测定塘库和谷地泥沙沉积量的测定法,计算的库区小流域土壤侵蚀量和泥沙输移比相对合理可靠,具有一定的参考价值。

Sediment delivery ratio is critical in evaluating sediment yield reduction caused by soil and water conservation. The Lingjiao Pond small watershed in the central area of the Three Gorges Reservoir was investigated. Soil erosion amount and SDR were calculated on the basis of pond and paddy fields deposition determined by 137Cs tracing technique for 1963-2013 years. Difference characteristics were proposed for SDR with three types of soil erosion amount estimation. Results showed that deposition amounts in pond and paddy fields in the study area was 1,835. 75 t and 3,781. 80 t,respectively. Soil erosion amount estimated by determination,interpolation as well as model method was 5,821. 52 t,7,240. 50 t and 10,504. 25 t,respectively. SDR for 1963-2013 years in the small watershed differed apparently when different soil erosion amount estimation was utilized. Results of soil erosion amount and SDR were reliable with application of the determination method（valley and pond sedimentation amount determined by 137Cs technique） proposed in this study.