三峡水库支流库湾水环流模式演变规律及其环境效应研究

Algal blooms happened frequently in the tributaries of the Three Gorges Reservoir(TGR). It has been shown that the algal blooms is influenced significantly by the density currents in the tributaries. While, the density currents, driven by the upstream inflows and TGR mainstream intrusion which intrude into the tributaries in different layers at different time, are various and complex. The density currents varies and alters during the interannual, yearly and even shorter time followed by resultant different water circulations associated with local vortexes and secondary circulations. And different environmental effects are found out responsible for different water circulation modes and variation processes. So it is necessary to further study the water circulation patterns and variation modes and environmental effects in the tributaries of TGR. Based on advanced fluid mechanics, this study takes the typical tributaries of the TGR as the object. Through field monitoring, numerical simulation and theoretical analysis, the water circulations and associated vortexes will be investigated and classified. The water circulation and associated vortex characteristics will be identified. Conditions of the occurrence, variations and development of the water circulations and associated vortexes will be studied. It will be also revealed that the mechanism of the different water circulations and local vortexes acting on the thermal structure, nutrient transport and distribution, as well as the euphotic depth and the mixing depth. The water circulations and associated vortexes will be selected which are effective on controlling the algal blooms. And the corresponding boundary conditions will be revealed. Hopefully, this study is able to deepen the mechanism investigation of the algal blooms and provide theoretical support for the ecological operation to control the algal blooms in the tributaries of the TGR.

三峡水库支流水华现象频发，已有研究表明水华的生消受分层异重流影响显著。在支流上游入流及水库干流倒灌水流的双向对流驱动下，库湾分层异重流形态复杂多样，且在年际之间、四季之间、甚至更短时间间隔内动态演变，在支流库湾形成多样的环流模式并伴生涡旋和二次环流。不同环流模式对水华的影响机理不同，因此有必要进一步研究三峡水库支流库湾水环流模式及其演变规律，探明环境效应。.本课题拟以现代流体力学为指导，以库湾环流模式及伴生涡旋为对象，通过野外监测、数值模拟及理论分析，系统研究库湾环流模式及涡旋特征并进行识别分类，揭示环流及涡旋发生、发展及演变规律，探明库湾不同环流模式及伴生涡旋对水温分层结构、营养盐输移和分布、真光层与混合层变化的影响机理，遴选对水华抑制有效的环流和涡旋，反演其发生的外界条件阈值范围。为深入认识三峡水库支流库湾水环流模式演变规律及环境效应，并通过生态调度防控支流水华提供理论基础和实践支撑。

项目以三峡水库典型支流香溪河库湾为研究对象，开展了三峡水库香溪河库湾水文、水质、水生态特性的野外调查，构建了三峡水库香溪河支流库湾立面二维模型，实现了三峡水库支流库湾水温-水流-水质-水生态耦合数值模拟，系统分析了支流库湾环流模式的形成条件、演替规律及关键影响因素，并分析了不同环流模式及其演变过程对水质、水生态的影响，通过评估多种环流模式对支流库湾水华情势的影响，遴选了有利于抑制水华暴发的关键环流模式，并阐释了关键环流模式及其演变过程对水华生消的影响机制，从环境流体力学角度为营造及利用环流模式解决生态环境问题提供了解决思路。在《Water Research》、《水利学报》等国内外期刊上发表已标注论文47篇，其中SCI源刊11篇，EI源刊16篇；申报发明专利3项；申报实用新型专利12项，授权12项；已出版专著1部，另完成专著初稿1部。大量现场监测及模型数据支撑构建了“十二五”国家科技部水专项三峡课题数据库，相关研究成果得到了国内外专家的认可，部分成果已在国内外相关领域推广应用，有力支撑了水库生态调度防控支流水华的相关科学问题的解决。