长江上游高洪水期泥沙输移特性

长江上游高洪水期(汛期)泥沙输移特性是决定三峡库区泥沙淤积的关键因素,直接关乎三峡水库使用寿命及综合效益的发挥。借助干、支流长系列水沙资料,分析了长江三峡水库入库寸滩站高洪水期泥沙输移特性,结果表明:近40 a来,寸滩站场次洪水中7 d洪量未出现趋势性变化,而7 d沙量显著减少,高洪水期输沙经历了“涨水输沙占优—涨、落水基本持平—落水输沙占优”的变化过程。2013年以前,寸滩站高洪水期径流及泥沙均主要来自于金沙江,而向家坝、溪洛渡水电站陆续投运后,2013—2019年寸滩站洪水场次(洪峰流量30 000 m³/s以上)共计14场。从径流来源来看,仅4场主要来自于金沙江,其余9场主要来自于嘉陵江,1场来自岷江;从泥沙来源来看,9场主要来自于嘉陵江,其余5场分别来自于沱江、岷江、横江,金沙江已不是寸滩站高洪水期过程中泥沙的主要来源区。研究成果可为三峡水库沙峰排沙调度、库尾减淤调度提供理论支撑,为长江泥沙治理提供保障。

Sediment Transport Characteristics during High Floods in the Upper Reaches of the Yangtze River

Sediment transport characteristics during high floods in the upper reaches of the Yangtze River are the key factors that determine the sedimentation in the Three Gorges Reservoir, and are directly related to the service life and comprehensive benefits of the dam. According to long series flow and sediment data, the characteristics of sediment transport during high floods at Cuntan Station are analyzed. Results demonstrated that in the past four decades, the trend of seven-day flood volume at Cuntan station has not been distinct, whereas the seven-day sediment transport decreased significantly. The high-flood sediment transport has experienced a process from being dominated by rising flow, to a balance between rising and falling flows, and then to be dominated by the falling flow. Before 2013, runoff and sediment during the high-floods at Cuntan Station were mainly from the Jinsha River. After the operation of Xiangjiaba and Xiluodu projects, Cuntan Station witnessed fourteen flood events (peak flow above 30 000 m³/s) in total, of which only four came from the Jinsha River, nine from the Jialing River and one from the Minjiang River in terms of runoff source, while from the perspective of sediment source, nine were from the Jialing River, and the other five came from the Tuojiang River, Minjiang River, and Hengjiang River, which implied that Jinsha River is no longer the major source of sediment transport during the high floods. The research findings offer theoretical support for the Three Gorges Reservoir’s sand peak and silt reduction regulation, and provide a guarantee for the Yangtze River sediment control.