小浪底水库调水调沙以来黄河下游游荡河段河床演变研究

Fluvial processes of channel geometry in wandering reach of the Lower Yellow River since water-sediment regulation of Xiaolangdi reservoir

基于2002年小浪底水库开始调水调沙后,黄河下游小浪底至高村游荡河段的98个断面实测数据,分析河槽的平滩面积、宽度、平均水深及宽深比等形态参数的时间和空间变化规律,得到了该河段的断面形态参数特征。以神堤和三义寨断面为界限,黄河下游游荡河段可分为三部分。至2017年,神堤以上和三义寨以下河段,河槽宽深比和河槽宽度小,断面面积增加基于河槽下切。中间河段大多宽深比较大,河槽断面面积的增加,同时受河槽宽度和下切深度的影响。河槽下切深度与宽深比负相关。陡门断面位于研究区中间位置,宽深比大,2002-2017年经历了由淤积到下切的过程,下切深度较小,成为河槽深度下切过程的空间分界点,其上游河槽下切速度由白鹤向陡门断面逐渐减小,其下游河槽的平均水深增加速度由柿子园向陡门断面逐渐减小。

Ninety-eight river channel cross-sections,from Xiaolangdi dam to Gaocun in the Lower Yellow River,are studied on the characteristics of channel geometry.According to the data of these cross-sections observed after the Xiaolangdi Reservoir operation in 2002,the bankfull channel dimensions of area,width,average water depth and width-depth ratio are analyzed.The studied reach of the Lower Yellow River can be divided into three reaches by Shendi cross section and Sanyizai cross section.The channel width between those two cross-sections increased rapidly,but the mean water depth increased slowly.Width of other reaches on both sides are stable.However,the average water depth increased rapidly.The average water depth changes showed negative correlation with width-depth ratio.Doumen cross-section is in the middle of the studied reach with big width-depth ratio,which was suffered from deposition to scour after 2002 according to the results of average water depth change.It is the cut-off point of channel down sream scour from Xiaolangdi dam to Gaocun.The processes of channel scour is from Xiaolangdi dam to Doumen cross section in upriver with time.However,the channel scour processes in downriver is from Gaocun to Doumen cross sections.