小浪底水库投入运用后 ,黄河下游在较长时期内受下泄清水影响 ,河道冲淤演变及排洪能力将会发生较大的变化。在现场查勘的基础上 ,通过对丹江口水库和小浪底水库拦沙初期下游河道演变、排洪能力变化特点的对比 ,分析了黄河下游防洪面临的新形势 :小浪底水库拦沙初期 ,下游河道发生冲刷 ,但艾山以下窄河段冲淤变化不大 ,近年来形成的淤积萎缩的状况难以很快改观 ;游荡性河段调整剧烈 ,工程出险机遇增大 ;河道水位流量关系中水流量以下部分同流量水位明显降低 ,中水流量以上部分水位降低幅度可能会明显偏小 ,防洪形势仍不容乐观 After the Xiaolangdi Reservoir is put into operation, the downstream of the Yellow River will be affected by the release of clear water in a relatively long period of time. The evolution of the scouring and silting of the riverway and its flood discharge capacity will change greatly. On the basis of on-site survey, this paper analyzes the new situation of flood control in lower reaches of the Yellow River through the comparison of the characteristics of the downstream channel evolution and discharge capacity in the early stage of sediment removal of Danjiangkou Reservoir and Xiaolangdi Reservoir: In the initial stage of sediment removal of Xiaolangdi Reservoir, However, there is little change in the scouring and silting in the narrow reach below Ai Mountain, and the situation of siltation and shrinkage formed in recent years is difficult to change rapidly. The adjustment of wandering reach is intense and opportunities for project risks increase. The water level is obviously reduced, the reduction of the water level above the water flow may be obviously smaller, and the flood control situation is still not optimistic