Abstract: The treatment and prevention of water bloom play a significant role in efficiently controlling water pollution，and the key to solve this problem is to understand formation mechanism of water bloom. Based on a further analysis for the formation process of cyanobacteria bloom in urban lake reservoir，and the whole process is simulated in laboratory，orthogonal experiment and rough set theory are combined to get key factors (DO，TP，TN，temperature and illumination)that can impact formation of cyanobacteria bloom and used as input parameters in establishment of mechanism model for the formation of cyanobacteria bloom in urban lake reservoir.Chlorophyll a is adopted as a characterization index for the formation of cyanobacteria bloom，and based on mechanism of interaction，a model of the process applied to describe cyanobacteria bloom formation in urban lake reservoir is structured.Meanwhile，the parameters involved in this model，such as G_max，I_s，∂，K， K_ab， D_max， m_p，can be estimated and nonlinearly optimized by improved PSO(particle swarm optimization)，which can highly enhance the model applicability and validation.The method provides an efficient approach for further study on formation mechanism of cyanobacteria bloom.

Key words: cyanobacteria bloom in urban lake reservoir, formation mechanism, orthogonal experiment, rough set theory;PSO

摘要： 水华防治是水环境污染治理的重点，而对水华形成机理的深入把握是解决这一问题的关键。在对城市湖库蓝藻水华形成过程深入分析的基础上，通过实验室模拟城市湖库蓝藻水华形成的整个过程，结合正交试验方法和粗糙集理论获取影响城市湖库蓝藻水华形成的关键因子——溶解氧、温度、光照、氮、磷，作为蓝藻水华形成机理建模的输入参量，以叶绿素a作为城市湖库蓝藻水华形成的表征指标，根据相互之间的作用机制构建了适合于描述城市湖库蓝藻水华形成过程的机理模型，同时通过改进的粒子群优化算法对机理模型中涉及的参数如蓝藻最大生长率、光半饱和常数、光系数、氨氮半饱和常数、溶解氧半饱和系数、蓝藻最大死亡率以及净损失率等进行非线性优化率定，提高了城市湖库蓝藻水华形成机理模型的适用性及有效性，为深入研究蓝藻水华形成机理提供一条有效途径。

关键词: 城市湖库蓝藻水华, 形成机理, 正交试验, 粗糙集理论, 粒子群算法