基于DEM祁连山南坡河网提取时集水面积阈值的确定

Determination of Drainage Area Threshold for Extraction of DEM-based Digital Drainage Network in Southern Slope of the Qilian Mountains

基于Arcgis10.0软件的水文分析工具,以30m分辨率的栅格DEM为数据源,提取了不同阈值下的祁连山南坡的河网,获取了不同阈值下的河源密度和河网密度,并根据河源密度和河网密度与集水面积阈值的关系确定了合理的集水面积阈值。结果表明,祁连山南坡合理的集水面积阈值应为12km2,在此集水面积阈值下,共有四级河道,河道总数为1 498条,总河长为3 522.26km,河源数为781条,河源密度为0.055 2个/km2,河网密度为0.105 9km/km2。当阈值为12km2时,提取的河网与真实河网吻合度高,总河长相对误差Re=5%,模拟效果较好。

With the DEM of 30 m resolution raster as the data source ,based on the hydrologic toolbox of Arcgis10 .0 software ,com-bining modeling tools to extract model of digital river networks ,digital river network diagram of southern slope of the Qilian Mountains is extracted under different thresholds .On this basis ,statistics and analysis capabilities of Arcgis 10 .0 are used to calcu-late riversource density and drainage density of each threshold .According to the relationship between riversource density and drainage densi-ty .The results show that ,the reasonable catchment area threshold of southern slope of the Qilian Mountains should be 12 km2 .Under the threshold ,there are 4 channels ,a total of 1 498 channels ,the total length is 3 522 .26 km ,river drainage density is 0 .105 9 km/km2 ,the total number of riversource is 781 .Riversource density is 0 .055 2 A/km2 .If the threshold is 12 km2 ,the extracted drainage networks fit best with the actual drainage networks .It indicates that the simuation result is the best when the threshold is 12 km2 ,Re=5% .