梯级水库拦沙引起河道泥沙的理化特性变化规律是目前泥沙研究领域亟待解决的重要科学问题，澜沧江干流梯级水电站对泥沙的拦截及其带来下游生态环境变化的议题，一直倍受国际社会关注。本项目选取澜沧江－湄公河流域为研究案例，通过野外考察、泥沙采样与实验室泥沙粒径分析、X射线衍射仪（XRD）矿物成分测定等实验研究，揭示梯级电站建设前后下游泥沙粒径、粘土/非粘土矿物含量、中值粒径-矿物成分关系沿程变化规律；并采用数理统计学方法，对比分析澜沧江梯级水电站建设前后泥沙粒径和不同粒径段泥沙矿物含量变化，探究大坝拦沙对下游泥沙粒径和矿物成分及其关系变化的影响，研究结果为深入认识澜沧江梯级水电开发对下游环境影响提供新观点，也为我国的东南亚环境外交提供新的科学依据。

Physical and chemical characteristics of river sediment changes induced by cascade hydropower project are key problems to be solved in the field of sediment research. Sediment trapped in the reservoirs on mainstream of the Lancang River as well as its downstream eco-environmental impacts are being paid close attentions by international community. This proposal will take the Lancang-Mekong River,a international river in southwestern China, as a case research. A mass of fied survey associated with sediment sampling will be conducted, then the sediment samples will be sieved by intervals for particle size analysis, after that the particles will be measured in a XRD instrument to investigate mineral compositions in the laboratory. Based on the field and laboratory works, Spatial changes of grain sizes and mineral contents of sediment and their relational expressions will be identified along the downstream. During the process of data analysis, relevant statistic methodologies will be employed to compare the pre-dams changes to those of post-dams, so that we could deduce the relationships between grain sizes and mineral contents of sediment.These prospective results have to be a new view within the researches on the impacts of hydropower dams on the downstream riparian environment, which acts as an important up-to-date reference for Chinese foreign affairs of environment in Southeast Asia.