黄河下游河道冲淤分布模式及冲淤特征

Distribution pattern and characteristics of sedimentation in the Lower Yellow River

为揭示黄河下游河道的沿程冲淤分布模式及分布特征,对黄河下游1952—2021年间共70年的河段实测冲淤量数据进行了系列统计分析。研究表明:(1)黄河下游河道存在7种沿程冲淤分布模式,其中全线冲刷、全线淤积、上冲下淤、上淤下冲等4种为基本模式。上淤下冲模式的冲淤临界位置在孙口附近,上冲下淤模式的冲淤临界位置在游荡性河段。各模式对河道整体冲淤的贡献率存在较大差异,两边冲中间淤模式对冲刷量的贡献率最大,全线淤积模式对淤积量的贡献率最大;(2)1952年以来,黄河下游河道沿程冲淤分布模式的变化过程可分为1952—1959年、1960—1985年、1986—1999年、2000年后共4个阶段;(3)各河段冲淤量大小以0点为中心近似呈偏态分布,冲淤量在多年尺度下具有沿程减小的趋势性特征以及“冲久必淤、淤久必冲”的周期性特征;(4)各河段整体冲淤发生年数差别不大,反映了河道冲淤的平衡趋向性;70年内淤积于黄河下游河床底部的泥沙有一半左右被冲走,花园口到孙口河段的累计冲淤量接近下游总冲淤量的8成,孙口以下河段很小;(5)全线冲刷模式为小浪底水库运用后下游河道的主要冲淤模式,小花段前期淤积的泥沙基本被冲完,夹高段、高孙段及孙艾段仅冲走了前期淤积泥沙的二到三成。研究结果总结了黄河下游河道的沿程冲淤分布模式,分析了冲淤分布特征,有助于深化对下游河道冲淤现象的整体认识。

To reveal the distribution pattern and characteristics of sedimentation along the Lower Yellow River(LYR),a series of statistical analyses were conducted based on the measured data of sedimentation in each section of LYR from 1952 to 2021.It was found that:(1)There are seven longitudinal distribution patterns of sedimentation,among which the whole-line erosion,the whole-line deposition,the upper erosion and lower deposition,the upper deposition and lower erosion are the four main patterns.The critical position of the upper deposition and lower erosion pattern is near Sunkou station,and the critical position of the upper erosion and lower deposition pattern is in the wandering river section.There is a big difference in the contribution rate of each pattern to the overall sedimentation of the river channel.The largest contribution rate to the amount of erosion is the pattern depositing in the middle and eroding in the upper and lower reaches,and the largest contribution rate to the amount of deposition is the pattern of whole-line deposition.(2)The variation process of the longitudinal distribution pattern of sedimentation since 1952 can be divided into four stages:1953-1959,1960-1985,1986-1999 and after 2000.(3)The distribution of the amount of sedimentation in each river section is mainly a normal or skewed distribution centered on 0 point.The fluctuation of the amount of sedimentation has the trend of downstream decreasing at the multi-year scale and the periodic characteristics of a long time of erosion will silt,a long time of erosion will scour.(4)The overall frequency of sedimentation in each river section is not much different,reflecting the equilibrium tendency of river sedimentation.In the past 70 years,only about half of the sediment deposited at the riverbed in the Lower Yellow River has been washed away.The cumulative amount of sedimentation from Huayuankou station to Sunkou station is close to 80%of the total amount of sedimentation in the lower reaches,and the river below Sunkou station is very small.(5)The whole-line erosion is the main pattern after the operation of the Xiaolangdi Reservoir.The sediment deposi4ted in the early stage of the Xiaolangdi-Huayuankou section is basically washed out,and the Jiahetan-Aishan section only washed away 20%to 30%of the sediment deposited in the early stage.The results summarized the distribution patterns of sedimentation and analyzed the distribution characteristics of sedimentation,which was helpful to deepen the overall understanding of sedimentation phenomena in the Lower Yellow River.