AVALIAÇÃO DE BASES SRTM PARA EXTRAÇÃO DE VARIÁVEIS MORFOMÉTRICAS E DE DRENAGEM

The Shuttle Radar Topography Mission (SRTM) data, constitute themselves into a viable and practical alternative to minimize costs and time on the execution of works and research that depends of Digital Elevation Model (DEM). The objective of this study is to evaluate and compare the accuracy of these bases SRTM NASA, EMBRAPA and TOPODATA on extraction processes of drainage, watersheds, altimetry, and in the calculation of the extent of rivers, considering different morphometric patterns. The study was structured into four steps: a) manipulating of three bases SRTM; b) automatic extraction of watersheds and drainage; c) comparison of the altimetric values, of watershed areas and of rivers extent on three bases used; d) assessment of the displacement of drainage extracted in relation to the hydrographic maps from DSG, in the scale 1:50000. The results showed that: (1) the TOPODATA data changed in a smaller level the altimetric data; (2) the biggest discrepancies on the rivers extent, occurred in most plain with meandering rivers watersheds, which were subtracted some meanders existing in the hydrographic maps from DSG; (3) was identified the trend of increase in the displacement of extracted drainages as the slope decreases and increases the sinuosity of the rivers; (4) between the drainage segments analyzed, were obtained displacements of less than 90 meters on drainage segments with slope above than 0.4%; (5) the drainage extracted from NASA SRTM presented the bigger accuracy, with 246 meters of medium displacement.