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黄河下游沿程出现的辫状河流(游荡型河流)、弯曲河流(弯曲型河流)、顺直河流(顺直微弯型河流)的转化现象引人关注,并有不同方面的专门研究。本研究针对以往研究的不足,通过对不同河型段的水沙演变、断面形态对流量的响应、河道断面演变、河床沉积速率及能耗率特征等方面,系统分析了不同河型段河道的水沙效应。认为黄河下游沿程出现的三类河型是由河道比降小、河床质细、洪枯水交替、粗泥沙输入少及大堤限制等因素起主导作用。其中顺直河流的出现是人工大堤的胁迫性产物。随着近年来水沙的阶段性减小,顺直河流在大堤的挟持下得以维持;弯曲河段河道的侧向摆动依然、宽度略微变窄,河床加积速率最大,但不会导致整个下游河道比降发生明显变化;辫状河段能耗率相对较大,冲淤强烈,滩槽更替频繁,但随着流量的减小,其能耗率明显减小,其比邻弯曲河流段的河道会逐渐曲流化,表现为弯曲河段的适度上延,但延伸有限。各类治理措施中,以中上游修建水库和淤地坝是最有效的,可拦截大量粗泥沙,从而降低下游河床的加积速率,以延缓悬河的发展。当然,针对决口险情的大堤建设是必要的,但要与不同河型段的河道稳定性相适应。
The phenomenon of braided rivers (wandering rivers), curved rivers (curved rivers) and straight rivers (straight slightly curved rivers) appearing along the lower reaches of the Yellow River is drawing attention and there are various aspects of special studies. In order to overcome the shortcomings of previous researches, this study systematically analyzes the characteristics of river courses in different river sections through the analysis of water and sediment evolution, the response of section morphology and flow, the section evolution of river channels, sedimentation rate and energy consumption rate of riverbed sections Water and sand effect. It is considered that the three types of rivers occurring along the lower reaches of the Yellow River play a leading role in such aspects as the decrease of the river course, the fineness of the riverbed, the alternation of flood and dry water, the less input of coarse sediment and the restriction of the dike. Among them, the straight river is the stress product of artificial dike. Along with the decreasing of water and sediment in recent years, the straight river can be maintained under the embankment of the levee. The lateral swing of the curved river is still slightly narrower in width and the maximum riverbed accretion rate does not lead to the entire downstream The specific ratio of river channel changes obviously. The energy consumption rate of braided channel is relatively large, and the erosion and deposition are strong. The beach channel alternation is frequent. However, the energy consumption rate decreases obviously with the decrease of flow rate. Will gradually meandering, showing a modest extension of curved river, but limited extension. Among all kinds of control measures, it is most effective to build reservoirs and check dams in the middle and upper reaches so as to intercept a large amount of coarse sediment, thereby reducing the accretion rate of the downstream river bed and delaying the development of the suspended river. Of course, the construction of the dike against the danger of a rift is necessary, but it should be compatible with the river stability of different river sections.