本文论述由于黄河上游清水区水资源的优先开发,中上游地区工农业用水的增长,而黄河中游地区的水土保持和支流治理的减沙作用不甚明显,龙羊峡水库投入运用后,汛期进入河口镇的水量大幅度减少,使汛期进入黄河下游的基流减小含沙量增加,高含沙洪水出现的机会增多.面临水少沙多的不利情况,应加强宽浅河道的改造及利用窄深河道输送高含沙水流的研究.

In recent years, although the sediment yield from source areas ranged from Hekouzhen to Longmen in flood seasons is less than before, but the mean sediment concentration of floods is continuously increased.The causes of such a fact are as follows.(1) Exploitage of water resources in clear water region takes precedence over all the other areas in the upper Yellow River.(2) Those tributaries in primary sediment yield areas of the middle Yellow River almost all carry heavy sediment load; (3) The harness and conservation of these in tributaries basins have no ohvious effect on sediment yield reduction.Especially the total runoff passing through the Hekeuzhen Station in flood season will be reduced greatly once again when the Longyangxia project.a large reservoir with long-term regulating capacity, will put into operation.or even the river flow will he cutoff for a long time during the irrigation sea-son.As a result, the basic flow in lower Yellow River may he reduced and the sediment concentration may be increased.Thus the occurrence opportunity for hyper-concentrated flood may he increased.The lower Yellow River will face an unfavourable situation with larger amount of sediment and less water in flood seasons.Therefore the problem how to remould the wide-shallow river channel of the lower Yellow River and fully utilize the narrow-deep river channel for transporting hyper-concentrated flow into the sea should he positively researched.