黄河内蒙古河段洪水演进与冲淤模拟研究

Numerical simulation research on the flood propagation and riverbed deformation in the Inner Mongolia reach of the Yellow River

研究洪水过程在黄河内蒙古河段的响应可为该河段的河道整治规划和黄河上游水资源开发方案的确定提供技术支撑。本文采用三维水沙数学模型,对黄河内蒙古巴彦高勒至头道拐河段开展了不同量级洪水过程的模拟研究。结果表明:洪水演进方面,现阶段巴彦高勒到头道拐的洪水演进时间较20世纪80年代有所增加,并维持在7～9 d;其中三湖河口以上河段河槽是主要的行洪区间;往下游发展,水流漫滩程度逐渐加大。河床冲淤方面,通过合适的水沙搭配和持续的洪水过程可实现该河段淤滩刷槽的有效调控;且主槽冲刷强度同流量之间存在非线性响应关系,并在流量2 500 m^3/s时输沙能力达到最大。此外,典型弯曲河段裁弯取直过程的模拟表明,持续的大流量洪水过程是实现局部河段自然裁弯的必要条件,通过裁弯取直可有效提高河段的输沙能力。

Research on the flood process in the Inner Mongolia reach of the Yellow River can provide the key support to the river regulation and water resource development in the upper reach of the river. The aim of this study was to investigate the response to the different scales of floods in the Inner Mongolia reach through a three-dimensional model, in which the simulation region is from Bayangaole gauging station to Toudaoguai gauging station. The simulation results show that currently the time of flood propagation from Bayangaole to Toudaoguai generally requires 7-9 days, behaving larger than that in the 1980s due to the persistent deposition. Thereinto, the flows primarily discharge through the main channel in the reach between Bayangaole gauging station and Sanhuhekou gauging station. Meanwhile, the extent of overbanking gradually intensifies downstream. With respect to the riverbed deformation, it is effective to control the relationship between the incoming water and sediment to restrain the shrinkage of the main channel; and surely that there exists a nonlinear relationship between channel scouring and incoming water-sediment condi- ton. Additionally, the process of curve cut-off in the local reach is simulated by keeping the continuous large floods at the upstream. It indicates that the behavior of curve cut off could improve the sediment con- veying capacity, which can benefit the river training in this reach.