三峡水库运行对长江荆南三口水文和生态的影响

Eco-hydrological impacts of Three Gorges Reservoir 's operation on three outfalls of Chingjiang River

基于1990—2014年荆南三口五站实测原型日流量水文序列,采用Mann-Kendall法、累积距平法检验分析其水文特征与变化趋势,并应用生态水文变化指标体系和变化范围法评估分析了三峡水库运行对荆南三口河流33项生态水文指标变化的影响.结果表明:1990—2014年,三口年平均流量呈现显著减少趋势(P<0.05),减小率为19%,拐点年份出现在2003年,2003年前荆南三口年平均流量为1981.1 m^3·s^(-1),2003年以后的年平均流量为1603.25m^3·s^(-1),前后相差377.85 m^3·s^(-1).1—4月的平均流量明显增加,偏离度分别为1.58、1.86、0.83、0.62;5月下旬至6月上旬明显增加;7、8月有较小程度的减少,偏离度分别为-0.12、-0.10;蓄水期(10月)显著减少,偏离度达-0.40.年极小值流量均有较高程度的改变,年极大值流量中仅1、3 d年均极大值流量有中等程度改变,其他年极大值流量改变程度低.低流量过程改变程度高,而高流量过程改变程度低.

Based on the measured daily flow prototype sequence of five hydrologic stations in the three outfalls of Chingjiang River from 1990 to 2014,its hydrological characteristics and its changing trend was analyzed by using the Mann-Kendall statistical test and the cumulative anomaly method,while the effect of the operation of the Three Gorges on the variation of the 33 indexes of ecological hydrology was also analyzed by the index system of ecological hydrology and range of variability approach.The results showed an obvious decreasing trend in annual mean discharge with the confidence degree of 95% with a decrease rate of 19% during 1990-2014.The jump point appeared in 2003,with the annual mean discharge being 1981.1 m^3·s^（-1）before 2003 but 1603.25m^3·s^（-1）after.There was an obvious increase in monthly mean discharge from January to April（ the degree of deviation was 1.58,1.86,0.83 and 0.62 respectively）,an obvious increase in the late May and the early June,a slight decrease in July and August（ the degree of deviation was-0.12and-0.10 respectively）,and a significant decrease in October（ the degree of deviation was-0.40）.There was a great change in annual minimum flows while a slight change in most of the annual maximum flows and a moderate decrease in 1-day and 3-day maximum flow.It also had a great change in duration and frequency of the low-flow pulse and slight change in high-flow pulse.