基于DEM的干旱区河网系统模拟尺度影响分析--以柴达木盆地流域为例

根据SHREVE与STRAHLER提出的流域结构图,进行了基于DEM的河网系统自动提取的应用研究.以柴达木盆地为例,分析1:250000与1:100000地形图数据所建立的数字高程模型.在构建TIN模型中,选择样条插值方法构建基于等高线的数字高程模型方法;水流方向矩阵计算中格网的大小对结果有很大影响,在复杂地形地区表现得更明显,比较250,100,50 m3种格网尺度数据在模拟河网系统中的不同结果,主要表现为河网系统随格网变大而更密集;比较阈值分别为800,1 200,1 600时的河网结构,表明提取河流网络的计算阈值取全流域累积矩阵的平均值时,可以得到较好的图形效果.将数字模拟的结果与人工描绘的河网结构进行对比研究,提出了基于地貌单元研究结果的改善方法.

Scale impact on modelling drainage system in arid region based on DEM A case study of Qaidam Basin, China

Digital elevation models (DEMs) are important tools for modelling the process of modern environment and, due to their high precision, have become a key content in constructing distributed modern process models. Based on the two drainage structure orders from Shreve and Strahler, the techniques extracting channel network based on GRID are developed and used in Qaidam basin by employing several different DEMs based on the digitized contours of 1:250 000 and 1:100 000 of Qaidam basin. By comparison, the spline interpolation method on contours has better effects; when computing the flow routing matrices the grid size will affect the results significantly, especially in complex landform areas; and the best effect of delineation can be obtained by choosing the mean value of the accumulative matrices about the whole watershed as the calculated threshold extracting watershed network.