DEM-based Watershed Topographic Attributes Extraction and Analysis

This paper study topographic attributes extraction and analysis methods based on grid DEMs. We used mathematic statistics method and comparative analysis to analyze effect of DEMs with different resolutions on the outcome of topographic terrain extraction, including slope, topographic index (i.e. ln(alpha/tanbeta)), watershed area, and drainage network. The results show that effect of DEMs with different resolution on topographic attributes is different. Terrain is smoothed, the mean slope decreases, the mean value of ln(alpha/tanbeta) distribution increases, the total area of watershed increases, the count of subwatersheds decrease, the total length of streams decrease, and the drainage density decreases as DEMs grid size increase.