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通过建立河道水沙仿真系统模型,系统的模拟了天然状态下宁蒙河道泥沙的输移过程,并与现状条件下该河段泥沙输移过程进行比较.结果表明:龙羊峡和刘家峡水库建成运行后,由于水库拦蓄作用,宁蒙河段入口下河沿站1969-2003年累计减少输沙量25.9966×108t,说明上游梯级水库的蓄水拦沙作用显著地减轻了宁蒙河段的淤积过程.宁蒙河段的淤积主要原因是青铜峡水库和三盛公水利枢纽建成蓄水抬高了坝前水位,致使坝址上游河段河道比降减小,河流挟沙能力显著降低,河岸风沙的加入以及当地支流产沙突发性加入、宁蒙河段用水量不断增加,以及青铜峡、三盛公水库小水排沙等多重因素所致.人们不可能从根本上改变河流以及区间支流流域的自然特性,只能通过对治理沙源、疏浚河道、修筑堤岸的措施治理宁蒙河段,减缓或改善其淤积速率.
Through the establishment of simulation model of river runoff and sediment, the transport process of sediment in Ningxia channel under natural conditions was systematically simulated and compared with the current situation of sediment transport.The results show that: Longyangxia and Liujiaxia After the completion of the reservoir operation, due to the interception of reservoirs, the total sediment discharge of 25.9966 × 108t was reduced from 1969 to 2003 in the riverside station under the entrance of Ningmeng River Section, indicating that the water and sediment blocking effect of the upstream cascade reservoirs remarkably reduced the Sedimentation process: The main reason for the deposition of the Ningmeng reach is that the built reservoirs of Qingtongxia Reservoir and Shengshenggong Water Control Project have pushed up the water level in front of the dam, resulting in a decrease in the ratio of river courses in the upper reaches of the dam site, The incorporation of bank winds and the sudden addition of sand into the local tributaries, the increasing water use in Ningmeng reach, and the multiple factors such as Qingtongxia Reservoir and San Sheng Gong Reservoir, etc. It is impossible to fundamentally change the river and The natural characteristics of the tributary basin can only be managed by controlling the sand source, dredging the river and embankment, to slow down or improve the siltation rate.