在阐述地形信息表达研究进展的基础上，提出基于DEM地形单元多样性指数的概念和算法。地形单元多样性指数综合了高程、坡度、坡位、坡向、汇流量和水域信息等要素。其算法集成地形位置指数和地形湿度指数算法，采用图层叠加分析，设定分类、分级指标，进行重分类组合，划分地形单元类型，利用窗口分析法计算地形单元多样性指数。以四川省为试验区，利用精度为100 m的DEM数据和水域分布数据进行模拟计算，地形单元划分为13种典型类型，统计窗口半径设为900 m，计算出的多样性指数值小于0.5的区域仅占总面积的11%，大于0.75的区域达57%，符合实验区地形特征，并对算法进行了可行性分析和验证。结果表明，该算法提取的地形单元多样性指数可以有效反映地表形态的多样性特征及其变化。该研究结果为进一步探讨基于DEM地表形态信息的概念体系，以及从微观到宏观的地形信息空间分析研究创造了条件。

In this paper, based on review of the studies on methods and techniques of terrain information description, topographic unit diversity index (TUDI), a new concept and quantification method, was proposed. The diversity index integrates several terrain parameters, e.g., elevation, slope, slope position, slope aspect, water confluences and distributions information. By combining the algorithms of the topographic position index and the topographic wetness index, using layer overlay analysis method and appropriate indicators for classification and grading, TUDI algorithm re-classifies the types of topographic units, and then calculate the TUDI using the neighborhood statistics and analysis method. The results of the experiment in Sichuan Province as a test region using DEM (100 m×100 m) and waters distribution data (1:250,000, 2005) show that TUDI is a comprehensive index, revealing the complexity and variations of the true surface. In the process of calculation, the topographic units were divided into 13 different types. The topographic unit diversity index was calculated with the statistics window radius set to 900m based on division results of the topographic units. The areas with diversity index value less than 0.5 cover around 11 percent of the whole region; the areas with the value more than 0.75 take up as much as 57 percent. Basically the results of the calculation agree with the topographic features of the study areas. In addition to the experiment to test the reliability of the algorithm, the advantages and disadvantages of it were also evaluated. This research provides a good basis for constructing a conceptual system of DEM-based topographic attributes, as well as for the spatial analysis of terrain information from micro to macro scales.