| 引用本文: | 许全喜,李思璇,袁晶,杨成刚.三峡水库蓄水运用以来长江中下游沙量平衡分析.湖泊科学,2021,33(3):806-818. DOI:10.18307/2021.0316 |
| Xu Quanxi,Li Sixuan,Yuan Jing,Yang Chenggang.Analysis of equilibrium sediment transport in the middle and lower reaches of the Yangtze River after the impoundment of the Three Gorges Reservoir. J. Lake Sci.2021,33(3):806-818. DOI:10.18307/2021.0316 |
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| 摘要: |
| 以三峡工程为核心的梯级水库群联合调度运用显著改变水沙条件，坝下游河段出现长时间、长距离的冲淤调整，长江中下游沙量平衡分析是合理评估水库群修建对河道影响的重要依据，是河湖管理与保护的关键支撑.本文基于长时间序列原型观测资料，采用沙量平衡法分析长江中下游不同时空尺度泥沙沿程恢复特征，对比断面地形法计算结果，结合河道空间区域性特征，从临底悬沙测验误差、断面代表性及断面间距、河道采砂等多角度深入揭示两种方法计算冲淤量产生差异的主要原因.结果表明：（1）2003—2018年宜昌至大通河段冲刷泥沙10.76亿t，其中粒径d<0.125 mm的泥沙冲刷量占比达90.9%.以螺山为界，宜昌至螺山段“粗细均冲”，螺山至大通河段则“细冲粗淤”；（2）宜昌至大通河段2003—2018年沙量平衡法与断面地形法计算冲淤量相对偏差为71%，从沿程差异分布来看，距离三峡大坝坝址较近的宜昌至沙市河段两方法计算绝对差值较小，而沙市至大通河段差值较大，占宜昌至大通全河段绝对偏差的近86%；（3）宜昌至沙市河段河道采砂量占实测河床冲刷量的比例约为20%，临底悬沙对输沙量的改正比例为13.2%～26.7%（平均约为20%），修正后，沙量平衡法、断面地形法计算结果吻合相对较好；沙市至大通河段泥沙测验、固定断面布设、河道采砂等是导致沙量平衡法与断面地形法出现差异的主要原因. |
| 关键词: 沙量平衡分析 断面地形法 冲淤量 长江中下游 |
| DOI：10.18307/2021.0316 |
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| 基金项目:国家重点研发计划项目（2017YFC0405301）、湖南省重大水利科技项目（湘水科计[2017]230-16）和三峡水库科学调度关键技术第二阶段研究项目（0704143）联合资助. |
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| Analysis of equilibrium sediment transport in the middle and lower reaches of the Yangtze River after the impoundment of the Three Gorges Reservoir |
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Xu Quanxi, Li Sixuan, Yuan Jing, Yang Chenggang
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Bureau of Hydrology, Changjiang Water Resources Commission, Wuhan 430010, P. R. China
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| Abstract: |
| The operation of the Three Gorges Project has significantly altered the flow and sediment conditions, causing long space-time scale erosion and deposition adjustment downstream the dam. Analysis of the equilibrium sediment transport in the middle and lower reaches of the Yangtze River is an important basis for rationally evaluating the impact of the dam construction, and also a key support for the management and protection of rivers and lakes. Based on long-term series of observation data, the sediment balance method is used to analyze the sediment recovery characteristics in the middle and lower reaches of the Yangtze River. Comparing with the section topographical method, the reasons for the two different calculated results of scouring-silting amount are revealed from several factors including the error of the bottom suspension test, the cross-section representativeness or interval distances, and sand mining. The results show: (1) From 2003 to 2018, the Yichang-Datong reaches has scoured 10.76 billion tons of sediment, of which the erosion volume of the particles d<0.125 mm accounted for 90.9%. Taking Luoshan as the boundary, the river section from Yichang to Luoshan presents as “coarse and fine sediment scouring”, and the section between Luoshan and Datong is “fine sediment scouring and coarse sediment silting”; (2) The relative deviation of the calculated erosion and silting amount between sediment balance method and the section topographical method from Yichang to Datong in 2003-2018 is 71%. Longitudinal distribution of the absolute differences calculated by the two methods indicates that from Yichang to Shashi which is closer to the dam is smaller, while the river section from Shashi to Datong is relatively larger, accounting for nearly 86% of the absolute deviation of the entire reach from Yichang to Datong; (3) The amount of sand mining from Yichang to Shashi accounts for about 20% of the measured erosion, while the correction ratio of bottom suspended sediment transport is from 13.2% to 26.7% (average about 20%). After correction, the two calculation results are relatively fit. However, the main reasons for the calculated differences from Shashi to Datong include sediment test, fixed section layout, and sand mining. |
| Key words: Analysis of equilibrium sediment transport the section topographical method erosion-deposition amount the middle and lower reaches of the Yangtze River |
