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流域产沙是土壤侵蚀的重要反映,受降雨等自然要素和人类活动的共同作用。采用退耦理论的思想和差分方法推导出流域侵蚀产沙人类活动影响指数的简易估算方法,并对长江上游的金沙江、乌江、嘉陵江、岷江分别计算人类活动总体贡献率。结果表明,各流域人类活动对侵蚀产沙变化的贡献率达72%～97%,总体上属于抑制侵蚀的正向活动。长江上游输沙量呈阶段梯级变化,根据流域侵蚀产沙人类活动影响指数的距平累积变化的突变特征将1955～2009年划分为5个阶段并分析了每个阶段人类活动的主要特点及其对侵蚀产沙的影响。其中,20世纪80年代中期以前河流输沙量较大,主要与“一五”、“大炼钢铁”、“三线建设”、农村改革前期不稳定因素等密切相关,而70年代河流输沙量较小是受当时大搞农田基本建设和采取“挑沙面土”、“边沟背沟”等传统水土保持措施的影响,80年代中期后河流输沙量明显减少,主要受社会经济稳定有序发展、水保工程的实施及大兴水库建设等影响。
Sediment production in the basin is an important reflection of soil erosion and is affected by natural elements such as precipitation and human activities. Based on the idea of decoupling theory and the difference method, a simple estimation method for the human activity impact index of sediment yield and erosion in the river basin was deduced. The total contribution rate of human activities to the Jinsha River, Wujiang River, Jialing River and Minjiang River in the upper reaches of the Yangtze River was calculated. The results show that the contribution of human activities to the change of erosion and sediment yield in various watersheds reaches 72% ~ 97%, which generally belongs to the positive activity of inhibiting erosion. Sediment discharge in the upper reaches of the Yangtze reaches a step-by-step change. Based on the abrupt change in the cumulative change in the index of human activities affected by watershed erosion and sediment, the 1955-2009 years are divided into five stages and the main characteristics of human activities at each stage are analyzed Impact on Erosion and Sediment Production. Among them, the amount of sediment transported by rivers before the mid-1980s was relatively large, which was mainly related to the “Five-Year Plan”, “Steelmaking”, “Three Lines Construction” and the unstable factors in the pre-rural reform. In the 1970s, the small amount of river sediment was influenced by the traditional land and water conservancy measures such as popularizing farmland infrastructures and adopting “soil pick-up” and “ditch ditch furrows”. After the mid-1980s, The decrease was mainly due to the steady and orderly social and economic development, the implementation of water and soil conservation projects and the construction of Daxing Reservoir.