Delayed morphological adjustment of the Yellow and lower Wei Rivers upstream of the Sanmenxia dam at multi-temporal scales
Delayed morphological adjustment of the Yellow and lower Wei Rivers upstream of the Sanmenxia dam at multi-temporal scales
复制标题
三门峡大坝上游黄河、渭河下游多时间尺度的形态调整延迟
DOI：
10.1016/j.catena.2022.106035
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发表时间：
2022
期刊：
影响因子：
6.2
通讯作者：
Wu Baosheng
中科院分区：
文献类型：
--
作者：
Zheng Shan;Wang Hualin;Wu Baosheng
大坝上游河道演变对基准面变化的滞后响应尚未得到彻底的了解。本文根据三门峡大坝上游黄河中下游中国大坝1960-2018年的水量、输沙量、断面剖面和冲淤量等资料，研究了黄河中下游河道形态调整的滞后响应。在大坝截流后的头20年里，上游河道演变明显滞后于动态水位的变化，此时出现了退缩的淤积/侵蚀阶段。退行性淤积从∼向上游迁移200公里，到达黄河的支流，即渭河。基准面上升的影响可能在回水河段开始后向后传播，反映出间接的回水效应。大坝自1974年起实行“非汛期蓄清水，汛期泄浑水”的控制泄洪调度，水库普遍出现汛期冲刷、非汛期淤积的现象。侵蚀中心定义为汛期侵蚀速率最大的相邻断面之间的亚段，淤积中心定义为非汛期淤积速率最大的断面。结果表明，1974-2010年间，冲淤中心向大坝方向迁移了50-60 km，2010年∼之后，侵蚀/沉积中心向上游迁移。冲淤中心的位置不仅与当年的水沙条件和回水长度有关，而且与前4年的水沙条件有关，反映了航道整治的滞后响应或透水条件对航道形态的累积影响。这项研究有助于为未来的水库管理和对不同自然和人为干扰引起的基准面变化的延迟航道响应提供信息。
The delayed response of channel evolution upstream of dams to base-level changes has not yet been thoroughly understood. In this paper, we studied the delayed response of the morphological adjustment at the middle Yellow and lower Wei Rivers upstream of the Sanmenxia Dam, China, based on data of water volume, sediment load, cross-sectional profiles, and erosion/deposition volumes during 1960–2018. Channel evolution upstream of the dam obviously lagged behind the dynamic pool level fluctuation during the first approximately two decades following dam closure, when retrogressive aggradation/erosion phases were identified. The retrogressive aggradation migrated ∼200 km upstream to the tributary of the Yellow River, i.e., the Wei River. The impact of base-level rise may propagate backwards behind the beginning of the backwater reach, reflecting indirect backwater effects. The dam has been operated by the controlled release of “storing the clear water during nonflood seasons and discharging the turbid water during flood seasons” since 1974, and the reservoir has generally been eroded during flood seasons and aggraded during nonflood seasons. The erosion center was defined as the subreach between two adjacent cross-sections with the greatest erosion rate during the flood season, and the aggradation center was defined as that with the greatest aggradation rate during the nonflood season. The results showed that the erosion/deposition centers migrated towards the dam by ∼50–60 km during 1974–2010 and migrated upstream after ∼2010. The location of the erosion/deposition centers was related not only to the water and sediment conditions and backwater length in the current year but also to these conditions in the previous ∼4 years, reflecting the delayed response of channel adjustment or the cumulative impact of pervious conditions on channel morphology. This study helps to inform future reservoir management and the delayed channel response to base level change caused by different natural and anthropogenic disturbances.