基于DEM与河网密度的水系提取与应用——以澜湄流域为例

Drainage Network Extraction and Application Based on DEM and River Network Density Method:A Case Study of Lancang-Mekong River

以澜沧江-湄公河流域为研究对象,提出一种基于90 m分辨率的数字高程模型(DEM)和河网密度法的水系提取方法。基于ArcGIS中水文分析模块和缓冲区工具,引入数字化河网作为水系提取的影响条件,以实际水系修正主要河道的高程值;再采用河网密度法确定最佳集水面积阈值,并依据流域自然分水岭、流域控制面积以及干流主要水文控制站要素划分子流域;结合中央气象台精细化智能网格降水产品,分析不同子流域尺度对强降雨反映效应。结果表明,澜湄流域最佳集水面积阈值为129.1 km 2,数字水系河流相对误差为7.5%,河网套合差为2.5%;精度检验吻合程度较高,提取水系与实际水系较为一致。

Taking Lancang-Mekong River as research object,a method of extracting drainage network based on DEM with 90 m resolution and river network density method is proposed.Firstly,based on the hydrological analysis module and buffer tool of ArcGIS,the digital river network is introduced as impact condition of drainage network extraction,and the elevation of main channel is corrected with actual drainage.Then the river network density method is introduced to determine the optimal catchment area threshold,and the sub-basins are divided according to the natural drainage divide of the watershed,the control area of watershed and the main hydrological stations on the mainstream.Finally,combined with the intelligent grid precipitation product of National Meteorological Centre,the effects of different sub-basin scales on heavy rainfall are analyzed.The results show that optimal threshold of catchment area of Lancang-Mekong River basin is 129.1 km 2,the relative error of digital river network is 7.5%,and the river network matching deference is 2.5%.The accuracy test has a high degree of coincidence,and the extracted drainage networks are more consistent with the actual water system.