基于三角网DEM的地形特征提取算法

Extracting Topographic Patterns Based on Triangulated Irregular Networks DEM

基于不规则三角网DEM,提出一种新的单流向地形特征自动提取算法.算法主要有三个过程:(1)计算每个三角形的最大坡度和各边的过水面积来确定三角形上水流流向;(2)同时考虑三角形边汇流和面汇流作为河道的组成部分,进行河网追踪;(3)洼地作为局部小流域进行提取,并根据需要将洼地合并到其出口流域或保持洼地独立性.与已有的地形特征提取算法相比,本文算法无需进行洼地预处理,所提取的流域具有与良好的结构性,保持了原有三角网的拓扑属性,并具有较高的效率.对浙江东阳流域地形特征提取进行了算法测试,并对比了官方水系图和ArcGIS软件提取结果,表明该算法适用于地形特征快速提取,同时适用于基于不规则三角网格离散的分布式水文模型并行计算求解时网格的高效剖分与重组.

Based on TINs DEM,a new single-flow direction algorithm for topographic patterns extraction is proposed.The algorithm contains three main steps:(1)Flow direction is determined by calculating the steepest descent of each triangle and flow area of each triangle edge;(2)River networks are tracked for both channel flow and cross-triangle flow;(3)Depressions are extracted as local individual drainage basins and they can be merged into their outflow drainage basins if necessary.The present algorithm does not need pre-processing of depressions and the extracted drainage networks are well structured with high efficiency.The proposed method has been tested in a case study for Dongyang City,Zhejiang,and the topographic patterns extracted are compared with official drainage map and those extracted by ArcGIS.This algorithm is suitable for automatic topographic extraction,and it can be applied in parallel computation for distributed hydrological model that use an irregular spatial discretization as it can split a giant mesh and recombine it in high efficiency,without changing mesh structure