Analysis on flood control situation in the Lower Yellow River after nine-year operation of Xiaolangdi Reservoir

Since Xiaolangdi reservoir has been operated for nine years,the flood situation in the Lower Yellow River has changed obviously due to the apparent adjustment of the river cross sections.The new flood characteristics is discussed in this paper based on the analysis of the existing river bed variation and the physical model test results.It is considered that the flow-conveying capacity has increased in the upper Huayuankou cross section,but the opportunity of over bank flood and the crest cutting function of floodplain to flood decrease,while the velocity of flood increases.If a flood like 96.8 flood happens in the river reach from Huayuankou to Sunkou,the high lip of floodplain partly prevents the upstream flow from returning the main channel,meanwhile the flow from the upstream floodplain makes the flood crest shape fat below Gaocun cross section.The high water level lasts longer and the flood situation becomes more serious.So the flood control situation is still serious in the Lower Yellow River and more attention on it from related departments should be paid.