澜沧江支流补远江对干流水温影响研究

Water temperature of Lancang River influenced by its tributary Buyuan River

水温是河流水环境重要的生态要素之一。河流干支流的径流过程和水温过程存在差别,下游干流水温过程既受到干流梯级电站下泄水温的影响,又会受到大型入汇支流水温的影响。文章通过原型观测和数值模拟相结合的方法分析了我国澜沧江下游主要支流——补远江入汇后对其下游干流河段的水温影响。研究表明,2015年9—12月支流补远江水温低于干流来流水温,当补远江流量较高而干流上游电站下泄流量较低时,支流入汇会使下游干流水温降低0.8℃左右。研究结果可为综合考虑干支流联调的梯级水电调控方案提供理论基础和技术支撑。

In this study,a combined field experiment and numerical modeling approach is used to examine the water temperature of the lower Lancang influenced by its main tributary the Buyuan River.Water temperature has been observed at three mainstream hydrological stations:Mohan on Buyuan,and Yunjinghong and Guanlei(located downstream to Buyuan confluence)on Lancang.Analysis on these data shows a trend of the water temperatures at Guanlei and Mohan both highly correlated.We make numerical simulations of water temperature at Guanlei for the period of Nov.2014 to Nov.2015,and compare the calculations with the corresponding scenarios without Buyuan,revealing the influence of Buyuan’s discharge.Results suggest that during Sept.and Oct.2014,Guanlei’s water temperature could be effectively lowered by at most 1?C due to Buyuan’s discharge,while in the rest of the study period it was dominated by the temperature of the incoming Lancang mainstream.Actually this was a special two months during which the discharge of Buyuan with temperature lower than Lancang was relatively large,yet still smaller than the incoming Lancang mainstream,and the hydropower plants on the upper Lancang mainstream were operated in impounding mode.