黄河内蒙古河段河道冲淤演变与凌情响应机制

Response mechanism of ice floods to scour and silting evolution in the Inner Mongolian channel and reaches of the Upper Yellow River

黄河上游内蒙古冲积性河道凌汛问题突出,研究河道冲淤演变与凌情响应机制可为该河段防凌减灾提供技术支持。根据内蒙古河段凌情、河道冲淤演变资料,分析凌情变化表征指标及与之密切相关的河道冲淤演变特征指标,研究河道冲淤演变特征指标与凌情变化表征指标的响应关系。结果表明:河道冲淤演变的特征指标平滩流量与凌情表征指标冰下过流能力、槽蓄水增量关系密切,冰下过流能力为平滩流量的1/5左右,随着平滩流量减小而减小,而槽蓄水增量随着平滩流量的减小而增大,有利内蒙古河段防凌的平滩流量宜不小于2000 m^(3)/s,槽蓄水增量宜不超过14亿m^(3)。本研究成果可为内蒙古河段冰凌灾害防治提供参考。

The alluvial river flooding problem in Inner Mongolia is prominent along the upper reaches of the Yellow River.Studying the scour and silting evolution of the river and the response mechanism of the floods can provide technical support for flood prevention and disaster mitigation in this river section.According to data on ice flood and scour and silting evolution,this paper produces the response relationship between a scour and silting evolution characteristics indicator and an ice flood condition change representation indicator based on formulaic calculations and related analyses.The results show that bankfull discharge,a characteristic indicator of river scour and siltation evolution,is closely related to the characterization indicators for ice flood sub-ice flow capacity and trough water storage increment.The under-ice flow capacity is about 1/5 that of bankfull discharge,and it decreases as bankfull discharge decreases.In addition,the channel detention increment increases as bankfull discharge decreases.The safety flow capacity in the main channel for ice flood control should not be less than 2000 m^(3)/s,and the increment in water storage should be kept below 1.4 billion m^(3)in the reach.The preliminary results can serve as a major guide for ice flood control in Inner Mongolian reaches.