选取已连续25 年大规模水电开发的澜沧江为研究对象,建立了河流水沙特性受影响程度评价指标体系及指标回归还原模型,并采用层次分析法和因子分析法相结合的赋权方法确定指标权重；借鉴“边际效益”原理,结合基于河流水沙自然变幅确立的指标评价标准,建立了各指标受影响程度定量评价模型。利用所建立的方法与模型,综合定量评价了澜沧江水沙特性的受影响程度,结果表明：澜沧江水电开发以来(1986-2007 年),河流水沙特性总体受影响程度等级为很小的年数占72.7%,为较小的年数占18.2%,为一般的年数占9.1%,输沙受影响程度远大于径流；水沙特性受影响的变化过程呈“U”形,其主要原因是在漫湾水电站运行与大朝山水电站建设并存期,库区拦沙作用与电站施工增沙作用使输沙趋于平衡。本研究,为后续相关研究提供方法借鉴,为评估水电开发对澜沧江水沙特性影响提供新的依据。
The rivers in Southwest China are the major base for large-scale hydropower development, and its change and responses of sediment and runoff are quite complicated. The assessment of the change and response has been the focus topics for the cascade hydropower dams building. In this paper, the Lancang River, which has 25 years' large-scale hydropower development, was chosen as a study case for establishing the affected evaluation indexes system of runoff and sediment and the reduction model of indexes, determining the indexes weight by AHP and factor analysis method, and setting up the indexes affected level evaluation models using the "marginal efficiency" principle. After the assessment of runoff and sediment change under the cascade development in Lancang River based on these methods and the model mentioned above, the results are obtained as follows. (1) During the 30 years of the hydropower development from 1986 to 2007, the impact of sediment transport affected by the cascade development is much greater than that of runoff change; 72.7% of the years with "very low" impact level of sediment transport change, 18.2% with "low" level, and 9.1% with "average" level. (2) The change process of runoff and sediment level affected presents a "U"-shaped pattern of "high-low-high" under the disturbing Manwan dam running and Dachaoshan dam building, which indicates a balance of sediment change due to the joint effect resulting from sediment reduction by Manwan reservoir and sediment increase by the Dachaoshan dam building.
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