黄河宁夏河段河道演变及其影响因素分析

Analysis of the Channel Evolution and Influence Factors in Ningxia Reach of the Yellow River

通过对黄河宁夏河段下河沿、青铜峡和石嘴山三个水文站的水文泥沙资料的分析,初步揭示了水库修建及其运用方式对下游河道冲淤变化的影响。结合上述站点的河道大断面及加密断面的形态变化,得出黄河宁夏河段河道冲淤变化在银川平原的砂质辫状河段最剧烈,在青铜峡大坝下游不长的砂砾质辫状河段相对强烈,而在青铜峡大坝以上的卵石质辫状河段不明显。河相系数与水力半径的关系式表明:宁夏河段的河相系数主要取决于水力半径,而水力半径取决于断面平均流速,即黄河宁夏河段的河道演变取决于过水断面平均流速。

Through the analysis of hydrological and sediment data measured at Xiaheyan,Qingtongxia and Shizuishan gauging stations in the Ningxia reach of the Yellow River,the paper discovered the impact of reservoir operation method to the downstream channel scour and sediment.Combined with the change of channel cross profiles,the dramatic change of scour and deposition occurred in the sandy braided river reach in the Yinchuan plain,the relative strong changes occurred in the sandy-gravely braided river reach downstream Qingtongxia Reservoir,but inapparent changes took place in the pebble braided river reach above the Qingtongxia Reservoir.The fitted relation between river regime coefficient and hydraulic radius showed that the river regime coefficient is mainly influenced by hydraulic radius.But the hydraulic radius depends on the mean flow velocity.It means that the channel evolution of the Ningxia reach of the Yellow River is mainly influenced by the mean flow velocity.