新水沙条件下三峡库区库尾河段冲淤特性分析

Analysis of erosion-deposition characteristics in the tail area of Three Gorges Reservoir under altered water-sediment conditions

摘要

随着金沙江下游梯级水库投入运行后，向家坝站输沙量大幅减少，使得三峡入库泥沙也相应减少。为了解库尾河段在新水沙条件下的冲淤特性变化情况，依据长江上游干流、岷江及嘉陵江主要控制站实测水文资料，及多年三峡库尾铜锣峡至涪陵河段固定断面观测资料，对比分析2012年前后三峡入库水沙变化情况及库尾河段淤积变化情况。结果显示：较2003—2012年间相比，2013—2024年间寸滩站径流量无明显变化，输沙量减少约63%,年内分布更集中在汛期7—9月，库尾铜锣峡至涪陵河段淤积量减少约56%,7—8月淤积贡献率上升，11月淤积贡献率下降。结果表明，三峡入库泥沙的减少减轻了库尾河段的淤积，入库泥沙更为集中在汛期使得汛期7—8月的淤积量占年淤积量的比例上升，在汛期高含沙水流入库时，若有条件减小削峰幅度，可以更进一步减少库尾淤积。

Abstract

With the commissioning of cascade reservoirs in the lower reaches of the Jinsha River, sediment discharge at Xiangjiaba Station has decreased substantially, leading to corresponding sediment reduction in inflows to the Three Gorges Reservoir(TGR). To investigate the changes in erosion-deposition characteristics in the tail area of TGR under altered water-sediment conditions, hydrological data from main control stations on the Upper Yangtze mainstream, Minjiang and Jialing Rivers was analyzed, along with years of cross-section data from Tongluoxia to Fuling in the TGR tail reach. Comparative analysis of changes in inflow water-sediment into the TGR and siltation changes in the tail area of TGR before and after 2012.The result show that compared to the period from 2003 to 2012, there was no significant change in the runoff at Cuntan station during the period from 2013 to 2024, while the sediment discharge decreased by about 63%. The intra-annual distribution was more concentrated from July to September. The sediment deposition in the river section from Tongluoxia to Fuling decreased by about 56%. The contribution rate of sediment deposition increased during July to August and decreased in November. The result indicate that the decreased sediment inflow into the TGR has significantly alleviated sedimentation in the reservoir tail section. With sediment transport becoming more concentrated during flood seasons, the proportion of July—August deposition contribution to annual sedimentation rose.During flood periods with high sediment-concentration inflows, appropriately reducing peak-flow clipping could further mitigate tail-section sedimentation, provided operational conditions permit.

关键词

三峡库尾 / 水沙变化 / 水库淤积

Key words

tail area of Three Gorges Reservoir / water-sediment regime change / reservoir sedimentation

Author summay

郭荣鑫(1983—), 男, 高级工程师, 硕士, 主要从事水库工程的地质灾害防治、风险预测与管理研究。E-mail: [e-mail]