数值地形图的生成及其水文地貌特征评价

数值地形图(DEM)是利用地理信息系统(GIS)进行流域水文模拟的基础, 其精度直接影响模拟结果在没有现成的数值地形图时, 应用人员往往利用传统的地形图来生成它. 本文分别采用Arc/Info地理信息系统软件提供的哈奇逊法和不规则三角网五次插值法, 对一个实验流域的高程取样点进行插值, 生成了4种不同的数值地形图, 从凹洼分布、流域界定、河网提取、地面坡度和地形指数、以及地面径流汇成等方面, 对它们的水文地貌精度进行了比较. 结果表明, 两种方法都能生成由高程点群所反映的地形, 然而由于哈奇逊法能够结合流域的河网结构及其具有物理基础的水文地貌加强法来处理凹洼问题, 因此大大地提高了其所生成的流域数值地形图水文地貌特征精度.

The generation of digital elevation model and the assessment of its hydrogeomorphological information

Digital elevation model (DEM) is the basis for catchment hydrological modeling which utilizing geographical information system(GIS). Based on the Hutchinson's algorithm and quintic interpolation on triangular irregular(TIN)network provided by Arc/Info GIS software, four kinds of DEM with different grids are generated for an experimental catchment. These DEMs are compared in terms of depression distribution, catchment delineation, channel network extraction, land slope and topographic index and surface runoff routing. Results show that both methods can generate an overall pattern of the topography captured by the input data points. However, Hutchison's method can incorporate stream data and use a kind of algorithm with more sophisticated drainge enforcement to remove potential depressions in the process of DEM generation. Consequently, the DEM generated by this method is more elegant and closer to the reality in the sense of hydrogeomorphological information.