摘要
变动回水区河段的侵蚀基准面在蓄水期抬升,在消落期和汛期逐渐恢复为天然河段状态,因此变动回水区内碍航浅滩的冲淤特性将发生改变。以三峡水库变动回水区三角碛浅滩段为例研究浅滩年际年内的冲淤及碍航特性的变化。结果发现,水库蓄水位抬升到175 m前,三角碛浅滩段年内遵循"汛淤枯冲"的规律,年际间则由于上游来沙量大幅减少,水流处于不饱和状态而表现为累积性冲刷,且随着水流不饱和程度的提高,冲刷强度增大;2008年汛后三峡开始试验性蓄水后,三角碛浅滩段由天然河段变为变动回水区河段,下游侵蚀基准面的抬升使河段具有淤积的趋向,上游来沙减少和下游侵蚀基准面抬升共同作用的结果是本河段冲刷强度显著下降,同时也未出现累积性淤积的现象。由于年内泥沙输移过程发生改变,主要走沙时期从汛末推移到次年的消落期,在通航标准不变的前提下,三角碛浅滩段的碍航程度可能会有所上升。
During the impounding, channels in fluctuating backwater area become a part of the reservoir as the base level of erosion rises. And those channels are in natural state during rest time of the year. Thus, in response to different conditions, feature of deposition and erosion of channels in this area varies accordingly. Taking Sanjiaoqi shoal as an example, this article focuses on the transformation of shoals＇ characteristics of deposition and erosion and navigation-obstructing. Under the natural condition, as the results reveal, the shoal followed the law of sediment deposition on high-water period and sediment erosion on low-water period throughout a year. Besides, interannually cumulative sediment erosion resulting from coming sediment whose quantity sharply decreased is observed and sediment erosion developed as quantity of coming sediment reduced constantly. After the flood season of the year 2008, the storage level of Three Gorges Reservoir lift gradually and Sanjiaoqi shoal became a part of fluctuating backwater area. Rising of the channel＇s base level of erosion renders the channel a tendency of sediment deposition. Under the influence of decreasing coming sediment as well as elevated base level of erosion, previously severe sediment erosion is effectively alleviated and the channel shows no cumulative sediment deposition. Meanwhile, the sediment deposition period shows apparent change. Previously, sediment deposited in this area during the flood season could be effectively scoured when the flood receded. While, under the new condition, wholesale sediment erosion won＇t take place until the reservoir＇s storage level falls next year. Hence it is predictable that the channel condition of Sanjiaoqi shoal may deteriorate with the navigation standard remains unchanged.
出处
《水运工程》
北大核心
2015年第1期110-114,共5页
Port & Waterway Engineering
基金
国家自然科学基金(51209016)
黄金水道通过能力提升技术重大专项课题(201132822430)
关键词
三峡工程
变动回水区
浅滩
冲淤
碍航特性
Three Gorges Reservoir
fluctuating backwater area
shoal
sediment deposition ＆ erosion
navigation-obstructing characteristics
