西南山区河道型水库甲藻水华生消的水动力机制与调控研究

Recent years, dinoflagellate bloom occurred frequently in channel type reservoir in southwest area of China, threatening the regional water resources and environmental safety. As a major driving force, hydrodynamic condition can influence the key process in reservoir environmental system, thus playing a dominant role in algal growth and distribution. Hydrodynamic control of algal bloom in reservoir is one of most emergent things remained to be solved in field of freshwater environmental research. This project focus on blooming dinoflagellate species, which has been few studied and holds a significant particularity. The research is conducted to systemically study the influence mechanism of hydrodynamic condition on dinoflagellate growth, transportation, gathering and homogenizing process by combing multiple methods, including field observation in typical reservoir, data investigation, remote sensing interpretation, laboratory experiment and numerical simulation. A set of relation models are planned to be built by investigating the complex response of dinoflagellate kinetic process to multi-scale hydrodynamic condition, such as velocity, turbulence characteristics and thermal structure. Based on that, algal growth kinetic equation and vertical migration equation are expected to be modified and completed, and then a dynamic model coupling hydrodynamic, water temperature and water quality is going to be developed to describe the growth and migration of dinoflagellate. On this basis, exploring the hydrodynamic activation condition and mechanism of dinoflagellate bloom formation and fading, and attempting to establish a hydraulic control guidelines. The conclusion will further reveal the basic rule of algal bloom development, providing new parameters and methods for the formation of theory and key technology of algal bloom hydrau-control.

甲藻水华频发于西南山区河道型水库，对区域水资源与生态环境安全构成严重威胁。水动力作为主要驱动力影响水库环境系统的关键过程，可主导藻类消长与分布。水库水华的水动力调控是目前水环境与生态水利研究领域的重点与难点。本项目锁定研究相对匮乏且特异性显著的水华优势甲藻，结合典型水库原型观测、资料调查、遥感解译、室内试验与数值模拟等手段，系统研究水动力条件对甲藻生长-输移-聚集/均化的影响规律与作用机制。定量解析甲藻动态过程对流速、紊动、水温结构等多尺度水动力特征要素的复杂响应关系；以此完善水动力影响下的甲藻生长动力学方程，改进紊动、水温分层影响下的甲藻垂直迁移方程，构建水库水动力-水温-水质多场耦合的甲藻生长输移动力学模型；在此基础上，探索甲藻水华生消的水动力启动条件及机制，尝试确立其水力调控准则。成果将有助于进一步揭示水华形成与发展的基本规律，为藻类水华水力调控理论与关键技术形成提供新参数和新方法。

本项目瞄准“重大工程生态环境效应及调控理论”这一核心科学问题，研究对象锁定在西南山区河道型水库中频发、特异性显著但研究相对匮乏的甲藻水华，以水库水动力过程为着眼点，系统研究水库甲藻水华生消的水动力作用规律与调控机制。通过开展连续三年的典型水库原型观测，结合资料调查、遥感解译、室内试验与数值模拟等手段，多维度解析了甲藻水华生消的时空特性，建立了甲藻动态过程对流速、紊动、水温结构等多尺度水动力特征要素的响应关系；依托所确立的甲藻生长限制流速、甲藻垂向迁移特征速度等定量关系，将水动力对甲藻的直接作用首次引入藻类生长模型，确立了专门面向甲藻占优群体的生态模型参数体系，分别构建了水动力-水温-水质-甲藻动态的立面二维与三维耦合模型，实现了甲藻生消与多场特性的同步精细解析，获得了令人满意的模拟效果；在此基础上，进一步阐释了流动、掺混、层化和滞留等不同水动力作用对甲藻水华发展过程的关键作用机制，建立了甲藻水华生消的复杂动力场阈值体系，进而识别了甲藻水华生消节点的水动力主导机制及启动条件，初步确立了甲藻水华期水力调控的基本准则。成果很好地揭示了西南山区水库甲藻水华形成与发展的基本规律，为西南山区年轻水库甲藻水华的及早干预、以及藻类水华水力调控理论与关键技术形成提供了新参数和新方法。