APPLICATION OF FRACTAL TECHNIQUES TO THE COMPARATIVE-EVALUATION OF 2 METHODS OF EXTRACTING CHANNEL NETWORKS FROM DIGITAL ELEVATION MODELS

The extraction of channel networks from digital elevation models was c arried out using two different techniques: the ''flow accumulation met hod'' (which is based on the now almost traditional steepest descent f low routing) and the ''multilevel skeletonization method'' (which is b ased on curvatures in contours). Series of networks representing the s ame drainage basin were extracted with-each of the methods using diffe rent extraction thresholds. Various stream ratios and fractal dimensio ns were determined from these networks based on three different hierar chical models. The study shows that for each extraction method, all ra tios irrespective of hierarchical model exhibit similar variation with respect to extraction threshold. On the other hand, for the flow accu mulation method of extraction, the different types of fractal dimensio ns vary in different ways with extraction threshold while in the case of the multilevel skeletonization method all the fractal dimensions de crease as extraction threshold increases. We attribute this difference in the behavior of fractal dimensions to the difference in approach b etween the two methods of extraction. Apparently the multilevel skelet onization method employs a more natural scheme.