风驱动的水动力对太湖藻源性灾害过程作用机制

The disaster causing by the abnormal proliferation of cyanobacteria now seriously threaten the ecological integrity and sustainability of some large and shallow lake ecosystems. It is reported that the advection and diffusion resulted from wind-driven hydrodynamics has an important influence on these lakes. Basing on the advection and diffusion of hydrodynamics on the water substance and depending on the high-frequency automatic monitoring station, the influence of wind-driven hydrodynamics on cyanobacterial blooms and algae-induced black bloom in Lake Taihu will be studied by analyzing long-term wind and bloom data, synchronous hydrometry of wind-induced currents and waves, investigations of lake ecosystem under the prevailing wind, field observations of the formation and dissipation of algae-induced disasters, flume experiments of key ecological processes and developing the disaster- oriented three dimension numerical model. These studies mentioned above can help us to understand the spatial and temporal distribution of the wind and wind-driven hydrodynamics of Lake Taihu, make clear the processes of the formation and dissipation of the disasters and the function of hydrodynamics during the processes. Using the model output and measured data, the formation of the disasters also can be analyzed and the wind conditions for dissipating the disasters are assessed. Moreover, the possible changes of the algae-induced disasters will be calculated under the future wind conditions. These studies can be helpful to the forecast and early warning of the cyanobacteria-induced black blooms of Lake Taihu.

蓝藻异常增殖引起的灾害已严重威胁大型浅水湖泊生态系统安全和可持续性，而风驱动的水动力对流扩散作用对这类湖泊生态系统具有重要影响。本项目拟针对风驱动的水动力对太湖蓝藻水华和湖泛等藻源性灾害影响问题，以水动力对物质的对流扩散作用为主线，以高频自动监测站为依托，通过太湖风场和水华的多年变化统计分析、湖流和风浪多点协同观测、盛行风向下全湖生态综合调查、不同风场条件下藻源性灾害生消原位观测、关键生态过程室内控制实验及研发面向蓝藻致灾过程模拟的三维数值模型，弄清太湖风场的基本特征及风驱动的水动力结构时空变化规律；分析藻源性灾害生消过程，揭示风驱动的水动力迁移扩散作用在此过程中的作用机制；定量评估灾害发生的空间分布特征及驱散灾害所需的风场及水动力条件，并预测未来风场条件下蓝藻成灾过程的可能变化。研究可为太湖蓝藻水华及湖泛预测预警提供服务。

本项目以正遭受严重富营养化的太湖为研究对象，通过对太湖风生水体运动的研究，阐明太湖水动力的时空变化规律，揭示了水动力对藻源性灾害的作用机制。项目取得了显著的成果：（1）基于水动力学基本理论与方法，通过应力分析和周期性计算，初步阐明了太湖实际全湖流场的基本特征及其驱动因素，揭示了全湖流场对季风、湖陆风和台风的响应机制。（2）对浅水湖泊风浪及其对水土界面作用机制开展了研究，阐明了太湖风浪时空分布特征及掀沙模式，确定了风浪引起的底泥悬浮的判定标准，研发了风浪监测设备、计算方法和预报模式。（3）全面系统的研究了水动力对蓝藻水华作用机制，首次明确提出太湖流域风场持续减弱将使得蓝藻水华出现时间延长和规模扩大的观点，为涉太机构和人员提供了有价值的信息。（4）改进了自主研发的湖泊水动力-生态三维数值模型，研发了湖泊蓝藻水华和湖泛监测和预警系统，并将之应用于太湖和钱塘江蓝藻水华或湖泛的监测预警，取得了良好的生态环境和社会经济效益。近4年来，项目组共发表SCI论文12篇，中文核心论文7篇，授权发明专利2项，登记软件著作权2项，培养博士和硕士研究生4名，获得省部级奖励2项。