| 孙昭华,周炜兴,周坤,周歆玥,陈立,李义天.江湖水沙输移与长江中下游造床流量的关系[J].水利学报,2021,52(5):521-534 |
| 江湖水沙输移与长江中下游造床流量的关系 |
| Relationship between the characteristics of water-sediment transportation in river-lake system and the channel forming discharge of the middle and lower Yangtze River |
| 投稿时间：2020-10-19 |
| DOI：10.13243/j.cnki.slxb.20200858 |
| 中文关键词: 长江中下游 江湖关系 水沙输移 造床流量 |
| 英文关键词: the middle and lower Yangtze River river-lake relationship water and sediment transportation channel forming discharge |
| 基金项目:国家自然科学基金项目（51879198，51579185）；三峡工程泥沙重大问题研究项目（12610100000018J129-03） |
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| 中文摘要: |
| 长江中游江湖系统滞洪沉沙作用对干流造床流量会产生一定影响。针对该问题，选取枝城至大通为研究河段，以1953年至三峡水库蓄水前水沙资料和2002年河道地形资料，采用多种方法估算了长江中下游造床流量，分析了江湖水沙输移对受分流、汇流影响河段内造床流量的影响机制。分析结果表明：城陵矶以上为分流沉沙区，中水和洪水流量概率密度存在微弱转折，当枝城流量大于35 000~40 000 m3/s的临界范围时，干流河道呈淤积状态；城陵矶以下为汇流稀释区，中洪水流量概率密度呈分段幂函数分布，流量超过40 000 m3/s左右的临界范围时，流量-含沙量关系由正相关转为负相关。城陵矶以上的造床流量在28 000~35 000 m3/s范围，为沿程减小；城陵矶以下在36 000~44 000 m3/s范围，为沿程增大。荆江河段内，枝城来水来沙是决定造床流量的主要因素，分流分沙关系为次要因素，流量概率与流量-含沙量关系均会影响造床流量。在城陵矶以下，造床流量主要受中洪水流量概率分布影响，江湖系统调蓄洪水作用是影响造床流量的重要因素，沿程汇流对造床流量影响较小。三峡水库运行后，坝下游中洪水频率、水沙搭配关系均发生调整，但河床再造过程中，上述主要影响因素及其主次关系无变化。 |
| 英文摘要: |
| The flood detention and sediment trap effects of the river-lake system in the middle Yangtze River is significantly different from that of general river floodplains . These characteristics may affect the channel-forming discharge in the main stream. Aim at this problem， the long term water and sediment discharge data and long distance channel topography data pre the Three Georges Reservoir impoundment was collected，and two kinds of work was performed. Firstly，the channel forming discharges in the middle and lower Yangtze River were estimated using multiple methods. Secondly， the mechanisms of river-lake water and sediment transportation and the channel forming discharge were systematically analyzed in sub-reaches influenced by diversions or confluence. （1） The river was characterized by flow diversion and sediment deposition in the upstream reach of Chenglingji station， and the river was characterized by flow convergence and sediment concentration dilution in the downstream reach of Chenglingji station. In reaches influenced by diversions， flow frequency curve showed trend of decline and channel deposition was likely to happen when discharge was beyond the critical range of 35000~40000m3/s. In reaches influenced by confluence， flow frequency curves were well fitted with broken power law function and the positive correlation between discharge and sediment concentration became negative correlation when discharge exceeded the critical range of about 40，000m3/s. （2） The channel forming discharge estimated by various methods agreed with each other. It showed streamwise declining trend and ranged 28000~35000m3/s in upstream of Chenglingji， and it showed streamwise increasing trend and ranged 36000~44000m3/s in downstream of Chenglingji. （3） In upstream of Chenglingji， the channel forming discharge was mainly determined by incoming water and sediment， e.g. flow frequency and water-sediment relation of Zhicheng. In contrast， the diversion ratio of water and sediment was less important factors. In downstream of Chenglingji， channel forming discharge was mainly determined by the frequency of medium and flood flow. Thus， flood detention capacity of the river-lake system was an important factor affecting the channel forming discharge，and the influence of confluency along the reach was minor. （4） After operation of the Three Gorges Reservoir， the flow frequency and the water-sand relationship were both adjusted in the dam downstream reach. However，the influencing factors and their relations remain unchanged in the process of channel adjustment. |
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