Automatic delineation of drainage basins from contour elevation data using skeleton construction techniques

New methods for automatic delineation of drainage basins from contour elevation data are presented. As a fundamental preprocessing step, the points defining a set of contour lines are used to compute the Delaunay triangulation, the Voronoi diagram, and other structures known in computational geometry as the crust and the skeleton (or medial axis transform). By exploiting the skeleton extracted from contour lines, a recursive algorithm is then developed to solve critical topographic structures such as ridges, saddles, and peaks in a fully automated and accurate manner. Finally, the algorithm is further extended to deal with the construction of flow nets. Numerical experiments based on high‐accuracy contour elevation data of real terrains show that the proposed methods are able to process automatically complex topographic structures and to produce results comparable to those that can be interpreted visually from contour lines. The gain in accuracy over current state‐of‐the‐art solutions is generally found to be significant and to increase as the contour interval increases.