基于DEM的岷江上游数字流域的离散化

Spatial Discretization of Digital Watershed Based on DEM for the Upper Reach of Minjiang River

流域地形与土地覆被类型离散化是构建分布式水文模型的关键问题之一,文中通过地形坡向分析技术在栅格DEM基础上生成数字化的流域水系和流域边界,按照流域地形特征将整个流域从空间上划分成多个自然子流域;在每个子流域内部,通过土地利用和土壤分布数字地图的叠加,生成体现单一土地利用类型和土壤类型组合的水文响应单元,并将研究区岷江上游流域离散为31个子流域,136个水文响应单元(HRU),实现了数字流域的空间离散化,为构建分布式水文模型奠定了基础。研究表明:河道面积阈值的大小决定了离散子流域数目,也决定着水文响应单元的数量,具体流域的阈值需要进行比较分析来确定。

The discretization of the watershed terrain and the land vegetation type is one of the key problems to build a distributed hydrological model-the digital drainage network. Watershed boundary are created based on the grid DEM by terrain slope analysis, and various natural sub-basins can be divided according to the watershed terrain characteristics. Within each sub-basin, Hydrological Response Units reflecting single land use type and agrotype combination are built up through superposing the land use and soil distribution digital maps. With this method, the upper reach watershed of Minjiang River can be divided into 31 sub-basins and 136 HRUs, thus realizing the spatial discretization of digital watershed. The result shows that threshold value of the upstream drainage area determine the discretized sub-basins and the HRU numbers, and the threshold value of a particular basin will be decided through comparison and analysis.