| 摘要: |
| 三峡蓄水运用以来宜昌站水沙条件发生了明显改变，驱动下游河床发生新一轮调整。本文采用回归分析、机理分析等方法，探究了三峡工程运行前后长江宜昌-沙市段及沙市-监利段河床冲淤变化对宜昌水沙条件的响应规律。结果表明，宜昌-沙市段冲淤量与宜昌水沙指标间的关联度强于沙市-监利段且前者关联度随时间增强；研究河段月尺度河床演变对宜昌水沙条件不存在明显的滞后响应；基于宜昌月均流量分别构建的两个河段冲淤量回归模型可较好反映河床冲淤变化；根据所构建模型，三峡运用前宜昌-沙市段呈“小水小冲、大水大淤”的冲淤格局，冲淤转换的临界宜昌流量约为23500 m3/s，三峡蓄水后该河段全面冲刷，呈“小水小冲、大水大冲”，但随着床沙粗化冲刷量有所下降；三峡蓄水前沙市-监利段亦呈“小水小冲，大水大淤”的冲淤格局，冲淤转换临界宜昌流量约为22500 m3/s且同流量下的淤积量大于宜昌-沙市段，三峡蓄水后宜昌小水时该河段冲刷量略大于上游河段，但宜昌大水时该河段冲刷量明显更小。 |
| 关键词: 三峡工程 荆江 河床演变 宜昌站 水沙条件 |
| DOI： |
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| 基金项目:国家重点研发计划项目(2017YFC0405301), 中国博士后科学基金资助项目(2019M651890), 中央级公益性科研院所基本科研业务费项目(Y519008), 国家自然科学基金项目(41601376) |
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| Response of Riverbed Evolution of Yichang-Jianli Reach of the Yangtze River to Water and Sediment Conditions of Yichang Station |
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hu tengfei, shi yong, luan zhenyu, chen liangang, jin qiu, chen liming, xu yifan
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Nanjing Hydraulic Research Institute
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| Abstract: |
| Since the first impoundment of the Three Gorges Reservoir (TGR), water and sediment conditions of Yichang station have undergone a significant change, which triggered a new round of riverbed adjustment of downstream reaches. In this paper, regression analysis, mechanism analysis and other methods were used to investigate the response of riverbed evolution of Yichang-Shashi reach (YSR) and Shashi-Jianli reach (SJR) to Yichang water and sediment conditions before and after the TGR. Results show that, the correlation between scouring and silting amount (SSA) of YSR and Yichang water and sediment indexes is stronger than that of the SJR and the correlation of former reach becomes stronger with time. On a monthly basis, the delayed response of riverbed evolution to Yichang water and sediment conditions cannot be observed for both YSR and SJR. Based on monthly average Yichang discharge, the univariate regression model for SSA can well reflect riverbed evolution of both river reaches. According to the developed models, YSR riverbed before the TGR shows the pattern of “weak scouring under small discharge and strong silting under large discharge” and the critical Yichang discharge corresponding to the change of state is ~23500 m3/s. After the TGR, YSR riverbed shows the characteristics of “weak scouring under small discharge and strong scouring under large discharge”. The scouring amount of YSR gradually decreases due to riverbed coarsening. SJR riverbed has the same evolution pattern with YSR riverbed before the TGR. However, its critical Yichang discharge of state change is slightly smaller (~22500 m3/s) and its silting amount is larger than that of YSR under the same Yichang discharge. After the TGR, SJR silting amount is slightly larger than that of YSR when Yichang discharge is small, while the former becomes much smaller than the latter when Yichang discharge is large. |
| Key words: The Three Gorges Project Jingjiang River Riverbed Evolution Yichang Station Water and Sediment Conditions |
