GIS技术支持下的洪水模型建模

在复杂区域建立洪水模型时,计算网格的手工生成方法容易出错甚至不可行,自动生成算法则可大大节省计算网格生成的工作量。洪水模型中的计算网格与GIS栅格数据及不规则三角网空间数据结构非常相似,因此,GIS中成熟的网格自动生成算法可用于生成洪水模型计算网格。文章详细讨论了GIS支持下的洪水模型自动建立步骤,并以黄河下游花园口～夹河滩河段为例,利用地形图、土地利用图、水利工程设施分布、水文站点图等资料,通过自动生成网格及其空间拓扑关系,建立了洪水过程数值模拟模型,并详细解释了计算网格数据格式。

The construction of flood routing model supported by GIS Technology

The computational mesh should represent the geometry, physical properties and boundary conditions of the computational domain in the flood simulation model. Based on the cell shape the computational mesh can be classified into regular mesh and irregular mesh. The generation of regular mesh is easy and simple, and as for irregular computational mesh hydrologists usually generated it manually. Due to structure and shape similarity, the automatic TIN generation algorithm can be used to generate the computational mesh for flood simulation model. The detailed flood model construction process based on GIS is to (1) delineate the computational domain; (2) generate computational mesh; (3) generate the mesh topology; and (4) extract the model parameters. The model parameters include boundary conditions, initial conditions, hydrological and geomorphological parameters and as well as other parameters for controlling the model simulation process. GIS technology can provide some spatial analytical tools for extracting some of these parameters such as the manning coefficient(roughness parameter) and calculating the average ground datum of internal point of every mesh unit and the mesh nodes, improve the capacity for defining the spatial sub-units of the computational domain and provide a better method to discrete the computational domain with enough amount of computational mesh with suitable geometry. In the river reach from Huayuankou to Jiahetan in the Huanghe River these maps of topography, landuse, water conservation engineering, hydrological observation station were used to construct the flood simulation model, and the data structure of the computational mesh is described in detail.