三峡水库蓄水对长江与洞庭湖汇流区生态水文的影响

Influence of Three Gorges Reservoir Impoundment on Ecohydrology in the Confluence Area of Yangtze River and Dongting Lake

基于1990~2019年长江与洞庭湖汇流区的日流量数据,运用水文变化指标体系和变化范围法评估三峡水库蓄水对江湖汇流区水文的改变程度及其对鱼类繁殖产生的影响。结果表明:(1)汇流区整体的水文改变度为36.79%,呈现中度改变,年均1、3、7、30、90日最小流量,涨、落水率等水文指标改变程度较大,呈现中度或高度改变;(2)三峡水库蓄水改变了汇流区天然的生态水文过程,与四大家鱼生长繁殖相敏感的水文指标发生变化,使其产卵期推迟,鱼类产卵繁殖的数量和质量也大幅降低。揭示了三峡水库蓄水对江湖汇流区生态水文情势的影响,为该区域的生态保护提供有益参考。

Based on the daily flow series of the confluence area between the Yangtze River and the Dongting Lake during the period from 1990 to 2019,the variation characteristics of the flow in this area were analyzed by using Indicators of Alteration and Range of Variability Approach to evaluate the hydrologic regime alteration degree and ecological effect of the Three Gorges Reservoir in the confluence area.The results showed that:(1)The degree of overall changes in the confluence area was 36.79%,presented the moderate degree of changes.The annual average of 1,3,7,30,90 day minimum discharge,water rise and fall rate of hydrological indexes changed significantly,showing moderate or high changes;(2)The natural ecological hydrological process in the confluence area was changed by the impoundment of the Three Gorges Reservoir.The change of the hydrological index which is sensitive to the growth and reproduction of four major Chinese carps caused the delay of the spawning period,and the quantity and quality of spawning and reproduction decreased significantly.This study reveals the impact of the impoundment of the Three Gorges Reservoir on the eco hydrological regime of the confluence area,and provides a theoretical basis for the ecological protection of the area.