金沙江流域云南片水文极小值演变及生态基流保障分析

基于金沙江流域云南片内主要支流1968—2017年水文径流极小值及年月平均流量数据,采用一元线性回归、Mann-Kendall等分析其极小值演变特征,采用Tennant法及地区经验综合分析其河道生态基流,并对其生态基流保障程度进行了评价。结果表明:东北区、西北区为年极小值对应每100 km~2产流高值区,滇中区为低值区,地区差异显著,东北区年径流极小值呈现显著波动减少趋势,滇中区、中北区及西北区变化趋势不一;主要支流平均仅有47%的年份生态基流得到全部保障,53%年份水文极小值低于生态基流,其中东北区及西北区保障程度较高,滇中区保障程度低;预计东北区受天然来水影响、西北区部分河流受水利水电工程调度影响,生态基流保障压力将逐步加大,滇中区除昆明、曲靖部分河流生态基流保障程度将逐步得到改善外,其他大部分河流将持续处于高压状态。

Analysis of hydrological minimum evolution and ecological base flow guarantee in Yunnan area of Jinshajiang River Basin, China

Based on the minimum hydrological runoff value and annual mean flow data of the main tributaries in the region of Yunnan area in the Jinsha River Basin from 1968 to 2017, the evolution characteristics of minimum values were analyzed by linear regression and Mann-Kendall method, and the river ecological base flow were comprehensively analyzed by Tennant method and regional experience, and the protection degree of ecological base flow was evaluated. The results show that, the northeast and northwest areas of the study area are the high value area of the annual minimum value corresponding to the high yield area per 100 km², and the Dianzhong area is the low value area. The regional differences are significant. The annual minimum runoff value in the northeast region shows a significant fluctuation decreasing trend. The variation trend of Dianzhong area, North Central District and Northwest area is different. On average, only 47 percent years of ecological base flow are guaranteed and 53 percent years hydrological minimum value is lower than ecological base flow in the main tributaries, in which Northeast China and Northwest China have a higher level of security, while central Yunnan has a lower level of security. It is predicted that the northeast region will be affected by natural water inflow and some rivers in the northwest region will be affected by water conservancy and hydropower project dispatch. The pressure of ecological base flow security will gradually increase. In Dianzhong area, except for some of the rivers in Kunming and Qujing, the degree of ecological base flow protection will be gradually improved, most of the other rivers will continue to be in a high pressure state.