基于DEM的干旱区河网系统模拟——以柴达木盆地流域为例

Auto-construction Study on Drainage Systemin Qaidam Basin

数字地形模型是模拟现代环境过程的重要工具,建立具有高精度的数字高程模型成为构建分布式现代过程模型的重要内容,其中河流网络构成了流域水文模型的重要参数。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∶1000000比例尺地形图数据所建立的数字高程模型。相比较而言,在构建TIN模型中,样条插值方法在等高线内插分析中具有更好的效果;水流方向矩阵计算中格网的大小对结果有很大的影响,在地形复杂的地区表现更为明显,主要表现为随格网变大而河网系统更密集;提取河流网络的计算阈值取全流域累积矩阵的平均值,可以得到最好的图形效果。

Digital elevation models (DEMs) are important tools to model the process of modern environment, and the ones with high precision become a key content to construct 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.