三峡水库下游弯曲河型演变规律调整及其驱动机制

发布时间：2018-03-27 14:44

本文选题：水库下游　切入点：弯曲河型　出处：《地理学报》2017年03期

【摘要】：大型水库的兴建深刻改变了下游水沙输移特点,进而导致河床演变规律显著调整,水库下游弯曲河型对水沙过程改变响应敏感,是水库下游河床演变、航道整治、河势控制等方面研究的关键区域。本文基于1996-2016年的实测水文、地形资料,对长江三峡水库下游弯曲河型的演变规律及其驱动机制开展研究,结果表明:(1)三峡水库蓄水前,下荆江存在"凸淤凹冲"、"凸冲凹淤"两类弯曲河型,而三峡水库蓄水后均表现为"凸冲凹淤"的一致性规律;(2)在水库拦沙作用的影响下,下荆江河段平滩河槽存在累积性冲刷现象,冲刷部位集中于枯水河槽与基本河槽之间的低滩,冲淤部位调整主要由变化的流量过程所驱动,上游河势、河道边界以及支流入汇等因素均有一定驱动作用;(3)在三峡水库蓄水后缺乏大洪水的情况下,凸岸水流挟沙力随流量增加逐渐增强,水流对凸岸冲蚀力度在平滩流量级附近(20000~25000 m3/s)达到最强,平滩流量附近流量级的持续时间超过20天时,弯曲河道发生凸冲凹淤现象。而悬沙中造床粗沙的减少,增强了水流冲刷强度,加剧了凸岸的冲蚀程度。
[Abstract]:The construction of large reservoir changed the downstream water and sediment transport characteristics, resulting in significant adjustment of riverbed evolution, meandering river downstream of the reservoir of water and sediment change response is sensitive, evolution of riverbed reservoir downstream waterway regulation, key areas of the river regime control. In this paper, the measured hydrological terrain for 1996-2016 years, based on the data of evolution the law of the Yangtze River Three Gorges reservoir downstream river and its driving mechanism research results show that: (1) the Three Gorges reservoir, under the existing "convex and concave Jingjiang punch", "two kinds of convex concave punching and bending River, and after impoundment of Three Gorges Reservoir were" consistent with the convex punch concave; and (2) effects of sediment in reservoir under the Lower Jingjiang river channel bankfull cumulative erosion phenomenon exists, scouring the site focused on the low flow channel and the channel between the basic low beach, scouring position adjustment mainly by the stream. The driver, amount of the upstream river and tributary river boundary factors have a certain driving effect; (3) the lack of after impoundment of Three Gorges reservoir flood situation, theconvex sediment carrying capacity increased gradually with the increase of flow rate increases, the flow to the convex erosion dynamics in the bankfull flow magnitude (20000~25000 m3/s) near the strongest. The duration of the bankfull discharge near the traffic level for more than 20 days, curved river siltation. Concave convexity at reduced sediment bed building sand, enhanced water erosion intensity, erosion degree increased convex.

【作者单位】：武汉大学水资源与水电工程科学国家重点实验室;西北农林科技大学;
【基金】：国家自然科学基金项目(51479146,51609096)~~
【分类号】：TV147

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