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用3S技术对重庆忠县石宝寨的菱角塘小流域进行侵蚀单元的划分,通过137 Cs示踪技术配合GIS空间插值法,评估小流域1963年以来的地面侵蚀量;同时,以137 Cs定年法为主要研究手段,确定塘库不同层位的淤积泥沙的年龄,计算1963年以来小流域塘库泥沙淤积量,从而获得小流域以塘库入口为观测断面的泥沙输移比。研究结果表明:(1)不同土地利用类型的土壤侵蚀量差异明显,从1963-2013年这50年间,小流域侵蚀总量为7 240.5t,林地侵蚀总量为2 095t,坡耕地土壤侵蚀总量为5 145.5t,是林地侵蚀总量的2.45倍;(2)用137 Cs定年法进行计算得出小流域塘库淤积总量为1 927.5t,输出库外的泥沙643t;(3)计算菱角塘小流域1963年以来的泥沙输移比为0.36,小流域的低泥沙输移比说明流域内在坡面下方集中分布的水田以及修建的塘库能够很好拦蓄流域上部坡面的侵蚀产沙。
The 3S technique was used to divide the erosion units of the Shijiaotang catchment in Shibaozhai, Zhongxian County, Chongqing. The 137 Cs tracing technique and GIS spatial interpolation method were used to evaluate the ground erosion in the watershed since 1963. At the same time, Law as the main research methods to determine the age of silt sediment in different layers of Tongkuang reservoir and calculate sediment deposition amount of ponds and ponds in small watershed since 1963 so as to obtain the sediment transport ratio of the ponds with the entrance of ponds as observation section in the small watershed. The results show that: (1) There is obvious difference in soil erosion between different land use types. From 1963 to 2013, the total erosion in small watershed was 7 240.5t and the total forest erosion was 2 095t. The total soil erosion (2) Calculated by 137 Cs dating method, the total volume of ponds in small watershed was 1 927.5t, and the sediment outside the reservoir was 643t; (3) The sediment transport ratio of the Shantangtang catchment since 1963 is calculated as 0.36. The low sediment transport in the small watershed is better than that of the paddy fields which are concentratedly distributed under the inner slopes of the watershed and the ponds constructed can well block the upper slopes of the watershed Erosion and sediment production.