长江中游洞庭湖防洪系统水流模拟——Ⅰ．建模思路和基本算法

Flow Modelling of the Middle Yangtze River Dongting Lake Flood Control System Ⅰ.Modelling Procedures and Basic Algorithms

针对长江中游洞庭湖防洪系统规模庞大、水流复杂、资料短缺和预报时限紧迫的实际条件，提出了具有层次和模块结构特点、一维与二维水流模拟、水力学与水文学方法、理论模型与补充信息相结合的建模途径。所建模型的湖泊部分采用无结构网格二维非恒定流高性能有限体积格式，以适应湖区复杂的边界形状和保持水量平衡；河网部分采用一维非恒定流守恒型显格式，避免隐格式矩阵算法的复杂性，同时有利于与二维模型的耦合及与各种复杂连通关系的显式连接。这种一、二维混合非恒定流模型可用于长江干流、洞庭湖河网及湖泊。

Based on the modelling procedures and basic algorithms for the middle Yangtze River Dongting Lake flood routing model, this paper discusses some essential problems arisen in the process of model building, including special treatments of inner and outer boundary conditions, applications of real time flood forecast corrector models, data manipulation, and determination of model parameters. Special attention was paid to matching these arts with basic algorithms. The observed data of two flood events were used for model calibration and verification respectively . The results showed that dynamic processes of flood routing were clearly rebuilt, and appropriate general patterns of water levels and flow velocities or discharges were obtained, illustrating the merits of this model.