突变地形特征在DEM上的表达

黄土高原南部高塬沟壑区的地形，存在比较明显的塬边线和沟缘线等突变地形特征线，而这种地形特征在DEM表面的表达却缺乏必要研究。选长武县为研究区，将1:50 000地形图（等高线、高程点和河流等专题层）及其手工提取的地形特征线（塬边线、沟缘线和坡脚线）数字化；利用多要素构TIN方法和Hutchinson插值方法，分别在有无地形特征线参与的情况下建立10 m分辨率规则格网的DEM；利用地图代数运算和频率统计等方法，比较分析所建DEM表面的高程、坡度和剖面曲率等地形属性特征。结果表明:在ANUDEM插值（Hutchinson算法）情况下，地形特征线的参与，可显著改善DEM对地形特征的表达，既避免了平三角，又兼顾了地形的光滑和连续性特征；而在构TIN建立DEM的情况下则无明显影响。

Representation of Eroded Geomorphological Features on the Digital Elevation Model (DEM)

The eroded geomorphological feature lines such as plateau edge lines and gully edge lines alone with the discontinuous terrain are obviously existing in the gully area of the southern Loess Plateau, but the representation of this topographical feature in the DEM surface lacks of necessary research for how to represent that topographical feature lines. This paper selects Changwu County as the study region, and digitizes the 1:50 000 topographic maps (including contours, elevation points and rivers thematic layers) and its hand-drawn topographic features lines (including plateau sidelines, gully edge lines and the slope toe lines). This research established four rules grid DEMs with 10 m resolution, respectively using multi-element structuring TIN method and Hutchinson interpolation method, in the case of with or without topographic feature lines participation interpolation, and comparative analysis terrain attributes such as the surface elevation, slope and curvature characteristics between the four DEMs, by map algebra and frequency statistics method. The results show that, in ANUDEM interpolation (Hutchinson algorithm) case, representation of topographical feature in the DEM surface with topographical feature lines can be significantly improved, avoiding the flat triangle and taking into account both the smoothness and continuity of the terrain features, while topographical feature lines have useless impact on the DEM established by TIN.