Uma proposta para automatização do índice de dissecação do relevo

Abstract

The relief dissection index is a morphometric analysis which considers the valley’s depth and the interfluvial average size. Ross (1992, 1994) formalized this index which has several applications, such as relief segmentation, provide bases for the geomorphological mapping, study of the morphogenesis x pedogenesis balance and environmental vulnerability. The analog form of calculation and mapping of the dissection index is extremely costly as well as being subject to human error and differences of interpretation. Currently there is no method to perform fully automated calculation of dissecation index which considers both variables proposed by Ross (valley’s depth and interfl uvial average size). The goal of this paper is to present an automation routine calculation of dissection index for each pixel from a digital elevation model. The method is divided into four main stages: the digital elevation model treatment, the mapping of the valley’s depth degree, the interfluvial average size mapping for each watershed and the integration of these two last products. According to the Ross (1994) proposal, in the end of the mapping, the dissection values must be classified following a scale that ranges from very weak to very strong. When the resulting map of Ross classifi cation was compared to the three-dimensional model of the area, to the slope map and the drainage network we noted some inconsistencies, such as the strong dissection class occurring on flat regions and places where the valley’s depth degree is extremely low. Three other proposals for the dissection values were then suggested.