Avaliação altimétrica dos dados SRTM para a região amazônica / Altimetric evaluation of SRTM data for the Amazon region

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

18/12/2007

RESUMO

In large areas of forest cover, such as the Amazon region, there is an absence of detailed topographical charts. It can be explained by the lack of reliable data at a reasonable cost. The Digital Elevation Model (DEM) obtained by the Shuttle Radar Topographic Mission (SRTM) can be considered as the best topographical information available for a large part of the Brazil territory, its resolution is 3 arches - seconds (about 90m). The DEM generated by SRTM has been widely used for the extraction of topographical data for different purposes, including determining parameters for hydrological models. As it is expected to represent reality, the more realistic the parameters included in these models are, the more reliable the result will be. This DEM presents some problems in areas with forest cover because it is generated from the C band data and this radars wave is influenced by the vegetation. The aim of this study is to evaluate the performance of the DEM in the igarapé Asu experimental watershed. The area is located 100km north of Manaus. This watershed is completely covered by firm land forest. Data were collected from 4 transects, using the transverse direction of the slope. Each transect has been divided into plots of 20x25m, where the forest inventory was made, and the coordinates (latitude, longitude and altitude) were collected. The estimated profiles and those generated with the altimeter were compared. The main differences between the profiles occur in the slopes, the DEM underestimates the real slope, and, consequently the length of the ramps. In order to correct the features of the estimated transects related to the reference, a correction model was formulated. In spite of the influence of the vegetation in radar data extraction, the preliminary results show this is not the only cause of the relative differences between the reference profiles (collected in the field work) and the estimated profiles (extracted from the DEM).

ASSUNTO(S)

modelo digital de elevação amazônia topografia digital elevation model amazon (region) srtm srtm topography

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