不同DEM分辨率下山西省数字河网阈值分析  

Threshold analysis of digital river network in Shanxi Province under different DEM resolutions

作　　者：王莹 杨玫[1] 庞海熔 原世帆 WANG Ying;YANG Mei;PANG Hairong;YUAN Shifan(College of Water Resource Science and Engineering,Taiyuan University of Technology,Taiyuan 030024,Shanxi,China)

机构地区：[1]太原理工大学水利科学与工程学院,山西太原030024

出　　处：《水利水电技术（中英文）》2024年第9期71-84,共14页Water Resources and Hydropower Engineering

基　　金：山西省基础研究计划(20210302124074);国家自然科学基金(42271432);山西省水利科学技术研究与推广(2023GM14)。

摘　　要：【目的】为了探讨不同分辨率DEM数据下河网提取的最佳集水面积阈值,以及阈值对流域水文信息的影响,【方法】以山西省为研究区域,基于四种分辨率(12.5、30.0、90.0、1000.0 m)的DEM数据,利用Arc GIS提取河网并划分流域,采用河网密度法及与实际河网叠加分析,确定最佳阈值,并探讨阈值对流域水文信息的影响。【结果】结果显示:(1)12.5 m DEM下,当阈值大于10.000 km^(2)时,河网级别、河道数、各级河道长均趋于稳定,河网分为6级,与实际河网分级相同,当阈值为18.750 km^(2)时,河道总长约29024 km,接近实际河网。(2)四种分辨率最终确定的最佳阈值分别为18.750 km^(2)、22.500 km^(2)、28.350 km^(2)、40.000 km^(2),提取河网与实际河网最为接近。【结论】结果表明:(1)随着阈值增大,河网变稀疏,河源数、河道数、河道总长呈现不同程度的减少,阈值过大会导致主要河道缺失,河网长度缩短,无法准确地呈现出河网情况。(2)河网提取受DEM分辨率的影响较小,而受阈值影响较为明显。(3)与90.0 m和1000.0 m分辨率的DEM相比,12.5 m和30.0 m分辨率的DEM在最佳阈值范围内提取的河网与实际河网吻合度更高,因此更准确的河网信息需要较高分辨率DEM提供。(4)阈值对流域划分有较大影响,随着阈值的增大,子流域数量减少,子流域面积增大,子流域边界变得更为简单,总流域面积反而减少。因此,在选择最佳阈值时,需根据实际应用目的进行确定,并进行对比修正。不同分辨率的DEM数据需要采用相应的最佳阈值来提取河网,以保证提取结果与实际情况最为接近。[Objective]In order to explore the optimal catchment area thresholds for extracting river networks using DEM data of different resolutions and to study the impact of thresholds on watershed hydrological information,[Methods]the DEM data with four different resolutions(12.5 m,30.0 m,90.0 m and 1000.0 m)in Shanxi Province was used to extract the river networks and divide the watersheds using ArcGIS.The study determines the optimal thresholds through the river network density method and superimposed analysis with the actual river network and then investigates the impact of thresholds on the hydrological information of the watersheds.[Results]The result show that:(1)With 12.5 m DEM,when the threshold exceeds 10.000 km^(2),the river network level,the number of channels,and the length of channels at all levels stabilize,[Results]ing in the river network being classified into 6 levels,consistent with the actual river network.When the threshold value is 18.75 km^(2),the total length of the rivers is about 29024 km,which is basically consistent with the actual river network.(2)The optimal thresholds determined for the four resolutions are 18.750 km^(2),22.500 km^(2),28.350 km^(2) and 40.000 km^(2),[Results]ing in the extracted river network closely resembling the actual river network.[Conclusion]The findings indicate the following:(1)Increasing the threshold leads to a sparser river network,[Results]ing in varying reductions in the number of river sources,river channels,and total channel length.If the threshold is too large,it may lead to the absence of main river channels and a shortened river network,failing to accurately represent the river network situation.(2)River network extraction is less impacted by DEM resolution but significantly affected by the thresholds.(3)Compared to the 90.0 m and 1000.0 m DEMs,the river networks extracted by the 12.5 m and 30.0 m DEMs in the optimal thresholds match better with the actual river networks.Therefore,more accurate river networks information requires higher resolution DEMs.(4)

关 键 词：DEM分辨率 GIS 数字河网 集水面积阈值 河网密度法 山西省 径流 

分 类 号：TV12[水利工程—水文学及水资源]