DEM-based Geomorphological Mapping and Landforms Characterization of a Tropical Karst Environment in Southeastern Brazil

Guilherme Pereira Bento Garcia, Carlos Henrique Grohmann

This work presents a 1:10,000 geomorphological mapping of an area in southeastern Brazil, based on morphometric analysis of Digital Elevation Models (DEMs), while classical methods focus on photo interpretation. Data derived from the DEM include elevation, slope gradient, slope aspect, vertical and horizontal curvatures, amplitude, elongation and wavelength of landforms. These parameters were used along with slope shape and drainage patterns to classify the landforms according to the Land Systems method, in which portions of the landscape that presents similar terrains attributes are grouped from regional (low detail) to local (high detail) scales, respectively, Land Systems, Land Units and Land Elements. The S\~{a}o Paulo State geomorphological map at 1:1,000,000 scale is considered the best reference source, and was compared with the results obtained in this project. Two Land Systems, four Land Units and twelve Land Elements were identified in the study area. In this area, karst terrains are common and easily identified due their characteristics drainage patterns, amplitude and slope gradient. Karst terrain boundaries defined in this study do overlap with those defined in the state map, however the morphometric analysis allowed a better description of the terrain attributes used to define them. The terrain attributes derived automatically from the DEM enabled an accurate geomorphological classification of the study area. The methodology presented in this paper is considered effective for mapping landforms at a detailed scale and can be employed in regional scale mapping using coarser resolution DEMs.