水文变异下长江荆南三口河道内生态需水量变化及贡献因素

基于1951—2015年长江荆南三口5站实测原型年径流量序列,采用Mann-Kendall等方法检测其径流序列的突变年份.在此基础上,运用GEV概率密度最大流量法计算荆南三口河道内生态需水量,并从多时空尺度视角分析河道内生态需水量的时空差异及其贡献因素.结果表明: 研究期间,新江口、沙道观、康家岗、管家铺和弥陀寺水文站的第一次径流突变年份分别为1990、1959、1959、1972和1972年,并将第一次突变以前的月均流量序列作为水文变异前的水文序列.在水文变异条件下,长江荆南三口1—12月的各月生态需水量分别为69.63、26.15、55.65、452.65、2166.44、4660.83、10875.66、9966.49、7868.38、4773.60、1655.01和338.49 m³·s^-1.新江口、沙道观、康家岗、管家铺和弥陀寺5个水文站的年均生态需水量分别为901.57、507.00、221.30、1438.03和581.62 m³·s^-1.水文变异后,荆南三口满足河道内生态需水的频率大幅下降,由变异前的55%以上下降至变异后的20%以下,生态需水缺乏现象严重.影响荆南三口河道内生态需水时空变化的因素主要为不同时期水利工程、各行业用水量等人类活动.

Variation of ecological water demand and its contributing factors in the southern three outlets of Jingjiang River in the Yangtze River under the condition of hydrologic variation

Based on the measured original runoff data series at five hydrological stations in the southern three outlets of Jingjiang River in the Yangtze River from 1951 to 2015, variation years of runoff were tested by Mann-Kendall methods. Instream ecological water demands in the southern three outlets of Jingjiang River were calculated through GEV’s maximum flow of probability density. Spatial temporal variation of ecological water demand and its contributing factors were analyzed from the perspective of multi temporal and spatial scales. The results showed that, in the studied periods, the first variation years of runoff were respectively 1990, 1959, 1959, 1972 and 1972 at five hydrological Stations of Xinjiangkou, Shadaoguan, Kangjiagang, Guanjiapu and Mituosi. The monthly average flow sequence before the first variation was used as the hydrological sequence before hydrological variation. Under the conditions of hydrological variation, the ecological water demands each month were respectively 69.63, 26.15, 55.65, 452.65, 2166.44, 4660.83, 10875.66, 9966.49, 7868.38, 4773.60, 1655.01 and 338.49 m³·s^-1 from January to December. The average annual ecological water demands in the five hydrological stations of Xinjiangkou, Shadaoguan, Kangjiagang, Guanjiapu and Mituosi were 901.57, 507.00, 221.30, 1438.03 and 581.62 m³·s^-1 respectively. After the hydrologic variation, the frequency of meeting instream ecological water demand decreased significantly from more than 55% before the hydrologic variation to less than 20% after the hydrologic variation in the three outlets of southern Jingjiang River, and the shortage of ecological water demand became very serious. The main factors affecting the spatial and temporal changes of ecological water demand in the southern three outlets of Jingjiang River in the Yangtze River were human activities of water conservancy projects in the different periods and water consumption in different industries.