水利学报2026，Vol.57Issue(5)：767-781,15.DOI:10.3724/j.slxb.20250601
三峡建库后洞庭湖入汇对下荆江顶托特征的变化分析
Changes in the backwater effect of Dongting Lake inflows on the Lower Jingjiang River after the impoundment of the Three Gorges Reservoir
摘要
Abstract
Clarifying the new characteristics of Dongting Lake's backwater effect on the lower Jingjiang River after the impoundment of the Three Gorges Reservoir is a critical issue at present.Focusing on the river section from Jianli to Chenglingji upstream of the confluence between the river and the lake,Copula functions were employed to investi-gate the characteristics of flow coincidences between the river and the lake in different periods.Based on the flow dynamics of alluvial rivers,a balanced-state flow pairing relationship was proposed,and an index for assessing the backwater intensity of the mainstream was developed.On this basis,the occurrence probability and timing of backwa-ter events as well as the variation of backwater intensity during different periods within a year for the lower Jingjiang River before and after the impoundment of the Three Gorges Reservoir were quantitatively analyzed.The results indi-cate that,under the balanced state,the flow pairing between the river and the lake follows a nonlinear functional rela-tionship.This relationship is close to the long-term mean fitted line of river-lake discharges and can be used to deter-mine whether the mainstream is in a backwater or drawdown state.After the impoundment of the Three Gorges Reser-voir,the duration of Jianli discharges at the medium-low flow level increased,resulting in a 44.6％rise in the coinci-dence probability of both the mainstream and lake inflows being at medium-low flow.The coincidence probability of the mainstream at medium flow and lake inflows at flood level(exceeding 30,000 m³/s)increased by 5.4％.As a result,the erosional base level at the river-lake confluence decreased,and on an annual scale,the mean backwater intensity of the lake on the mainstream weakened.However,the timing of the mainstream being in a backwater state shifted from above-bankfull flow levels to medium flow levels.The occurrence of extreme backwater intensity far exceeding the historical values during April-July has increased,warranting long-term attention.关键词
三峡水库/下荆江/洞庭湖/流量遭遇/回水顶托Key words
Three Gorges Reservoir/lower Jingjiang River/Dongting Lake/flow encounter/backwater effect分类
建筑与水利引用本文复制引用
李芷晴,孙昭华,陈立,安姗姗,周炜兴..三峡建库后洞庭湖入汇对下荆江顶托特征的变化分析[J].水利学报,2026,57(5):767-781,15.基金项目
国家自然科学基金项目(52479074) （52479074）
水利部三峡后续研究项目(12630100100020J005) （12630100100020J005）
