| 摘要: |
| 本文基于河道洲滩变化特征、来水来沙条件和滩地植被的促淤效应，分析了抚河故道的淤塞成因。研究发现，1985年~2022年，抚河故道上游河段洲滩面积持续增长、主河槽淤塞萎缩。上游河段滩地植被生长茂盛，受滩地植被阻水影响，滩地流速降低，泥沙浓度沿程衰减，促进了上游河段泥沙淤积。上游河段来水来沙进入中、下游河段后，由于断面宽度扩大，平均流速沿程降低，导致中、下游河段发生泥沙淤积。此外，抚河故道引水量逐年呈减小趋势，年内水沙条件搭配不合理，小流量时发生淤积，大流量时又无法冲刷小流量沉积下的泥沙，使得河道不断呈现淤积态势。基于平面二维水沙数学模型，通过设计多种水沙调控情景、不同滩槽构造及植被分布等工况开展计算分析，提出了减淤措施：当抚河故道入口含沙量超过0.01kg/m3时，增加一定历时的大流量过程，控制流量在85~125m3/s区间，可以有效促进上游河段的由淤积转为冲刷。在中、下游河段实施切滩治理和植被分布调整，提高中、下游河段的水流挟沙能力，以减缓中、下游河段滩地泥沙的淤积态势。 |
| 关键词: 抚河故道 淤塞成因 减沙控淤 滩地植被 |
| DOI： |
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| 基金项目:国家自然科学基金项目(U2340216,52020105006); 江西省水利科技项目(202224ZDKT25); 湖北省科技创新计划重点研发专项(No.2023BCB110)资助 |
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| Study on the causes and countermeasures of Sediment deposition of small and medium-sized rivers in the floodplain – A case study of the Old Course of the Fuhe River |
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Zhang Song,Yang Zhonghua,Zhang Wei,Yang Liu,Liu Fangping,Su Tian
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State Key Laboratory of Water Resources Engineering and Management,Wuhan University
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| Abstract: |
| This paper analyzes the causes of siltation in the Old Course of the Fuhe River based on the sandbar evolution, water and sediment inflow conditions, and the impacts of siltation by the sandbar vegetation. It was found that from 1985 to 2022, the area of sandbars in upstream of the Old Course of the Fuhe River continued to grow and the main channel silted up. The sandbar vegetation in the upstream grows luxuriantly. Under the influence of water blockage by floodplain vegetation, the flow velocity decreases, and the sediment concentration decays along the reaches, which promotes sediment deposition in the upper reaches. After the incoming water and sediment of the upper reaches enter the middle and downstream reaches, the average flow velocity decreases along the reaches due to the widening of the section width, resulting in sediment deposition. Moreover, The diversion water volume of the old course of the Fuhe River shows a decreasing trend year by year. The water and sediment conditions in the Old Course of the Fuhe River are suboptimal. During periods of low flow, siltation occurs frequently, and during high-flow events, the river lacks sufficient power to flush away the sediment deposited during low-flow periods. This dynamic results in a continuous accumulation of sediment within the channel. Based on a two-dimensional mathematical model, we designed multiple water-sediment control scenarios, incorporating various sandbar structures and vegetation distributions. Through detailed calculations and analyses, we proposed the following countermeasures: When the sediment concentration at the inlet of the Fuhe River exceeds 0.01 kg/m3, introducing controlled high-flow events with flow rates maintained between 85 and 125 m3/s can effectively transform the upstream section from a state of siltation to scouring. In the middle and downstream reaches, applying sandbars-cutting techniques and adjusting vegetation distribution can enhance the sediment transport capacity, thereby slowing down the rate of siltation in these areas. These countermeasures aim to provide a valuable reference for similar small and medium-sized rivers, improving their siltation conditions and restoring and maintaining the health and stability of river ecosystems. |
| Key words: The old course of the Fuhe River Causes of sediment deposition sediment reduction and silt control floodplain vegetation |
