流速与藻类种群生长演替驱动-响应关系模拟研究

Water velocity has become a key factor lead to the outbreak of algae bloom, especially in the backwater zone of some tributaries influenced by jacking from the mainstream. Outbreaks of water bloom have great influence on the industry and agriculture production and the safety of drinking water.so it is important to reveal the relationship bwtween water vleocity and water bloom, and initiate some researches on regulation and algae controling. Though many researches have been carried out,but there are some problems left. So Taking Dangninghe Mouth as an examble in this work, quantitative relationship beween water vlocity and algae will be investigated. Two innovation points sof this study include: 1) revealing quantitative relationship of different types of algaes and flow velocity through flume experiment , and 2) developing a 3D algal growth and population succession model combined EFDC model with the result of flume experiment. different control measures for the algae blooms in 2010 have been evaluated. This study would provide a systematic method for the reaearch on water velocity and algae growth, population succession, and some technical support for regualtion of the Three Gorges Dams with an aim of algae controling. It has been listed in the "Strategy study report of the science and Marine engineering and water conservancy development (2011-2015)" as a key research.

流速已成为一些水体"水华"爆发的关键因子，尤其是受干流回水顶托影响的支流回水区。"水华"爆发对工农业生产和饮用水安全产生极大影响。国内外学者在辨析藻类生长与流速关系方面已开展大量工作，但仍存在问题，如流速与浮游藻类生长定量化成果还少有报道，考虑流速影响的浮游藻类生长、种群演替三维模拟更为罕见。为此，本研究拟以三峡库区大宁河口地区为研究区，通过室内水槽实验和数值模拟系统研究流速与藻类生长定量关系。重点开展两方面工作：1）其它环境条件恒定下，利用水槽实验获取不同类型"水华"典型藻种生长与流速限制函数关系；2）将成果与开源水环境模型EFDC的富营养化模块耦合，开发综合考虑流速、水温、光照、营养盐影响的藻类生长与种群演替三维模型，进而模拟不同水力调控手段对2010年研究区各次"水华"削减效果。本研究可为其它富营养化地区开展流速与藻类生长、演替研究提供方法，为开展水库调度抑藻研究提供技术支持。

三峡工程蓄水后，库区支流库湾连年爆发“水华”，且“水华”的种类不尽不同。流速是控制支流库湾地区“水华”优势种生长和种群演替的关键因子，研究流速与藻类种群生长演替驱动-响应关系，能够为水库开展通过调度手段抑制“水华”爆发提供技术支持。.本研究以三峡库区大宁河口地区为研究区，通过收集、整理、分析历史资料，梳理了该地区水华爆发的水动力、水环境特征，厘清了水华爆发的优势藻种，硅藻、蓝藻、绿藻优势藻种分别为小环藻、铜绿微囊藻、小球藻。通过室内水槽实验，获取了其它环境条件（水温、营养盐、光照）恒定下，大宁河口地区不同类型“水华”典型优势藻种（小环藻、铜绿微囊藻和小球藻）生长与流速限制函数关系。将实验成果与开源水环境模型EFDC的富营养化模块耦合，开发综合考虑流速、水温、光照、营养盐影响的藻类生长与种群演替三维模型，进而模拟不同水力调控手段对2010年研究区各次“水华”削减效果。.研究表明：（1）河口地区在水位快速消落期，水华爆发频繁，说明一定的流速条件对水华爆发有利，室内实验也证实这样的判断，各种典型优势藻种均存在适宜生长的流速范围，小环藻范围为小于0.15m/s、铜绿微囊藻为小于0.06m/s、小球藻为小于0.03m/s；（2）利用改进模型模拟的水温误差最小，总氮和总磷次之，叶绿素a误差最大，但仍能反映随时间的变化趋势；（3）与EFDC自带计算成果相比，改进模型对于藻类的模拟效果较好；（4）采用模型进行了水位调度抑藻研究，结果表明，有一定效果，但并不显著。.综上，本研究成果获取了流速与不同类型藻生长关系定量表达，提出了综合考虑流速、光照、水温、营养盐的三维藻类生长与种群演替模型，进行了水位调控抑藻初步研究，为水库调度抑藻提供了一定的理论支持和技术工具。