Automated relief classification of the Lajeado watershed, Campo Grande, Mato Grosso do Sul

Abstract

The wide variety of relief forms found on earth's surface requires accurate recognition for better understanding of geomorphic processes. The Geomorphons tool characterizes the landscape into ten unique but recognizable elements, namely: flat, summit, ridges, shoulders, spurs, slopes, depression, valleys, footslopes, and hollows. This work aimed to classify the relief of an urban-rural watershed with the Geomorphons tool using altimetric data from different sources (radar, optics and aerophotogrammetry) and with spatial resolutions (5, 12.5, 30 and 90 m) in order to illustrate how the cartography of the same region produced at different scales im-pacts the derived topographic characteristics. The software used was SAGAGIS. Automated classification showed that for images with lower spatial resolutions such as Alos Palsar (12.5), Aster (30), SRTM (30), SRTM (90), Topodata (30), many terrain features are generalized, not identified, or eliminated, because geo-morphic processes are dependent on the scale of phenomena. The relief phenotypes derived from the DEM generated with aerophotogrammetry data (scale 1:10,000), allowed a more realistic discretization of the characteristics of the relief of the Lajeado watershed. For the relief phenotypes derived from DEMs generated with large cartographic scale data and with different spatial scales (5, 10, 20 and 40 m), it was found that in urbanized landscapes mappings at the cartographic scale 1:10,000 and DEMs with spatial resolution of five meters, allow a more realistic classification of relief phenotypes.