Estimativa da evapotranspiração regional em área de ocorrência do Sistema Aqüífero Guarani – Vale do Rio dos Sinos – RS: uma aplicação de técnicas de sensoriamento remoto

Abstract

The evapotranspiration (ETo) assessment, main factor of the regional hydrologic balance, is an essential issue to evaluate the surfitial in filtration and groundwater recharge, as well as for planning sustainable use. The satellite images allows a land use monitoring and a spatial analysis of the estimated ETo, what is an improvement of evaluation in comparison whith traditional techniques. In this way, this work deals with Landsat-TM, Landsat-ETM+ and NOAA-AVHRR images, as well with meteorological data and atmosphere radio profiles, estimating the maximum EToTs by adapting the Penman-Monteith model to remote sensing procedures. The results are showing an 950 meters horizontal precision off georeferencing NOAA – AVHRR images. The EToTs values obtained are about 5.41 mm/day in the summer (December/2003) and 2.60 mm/day in the winter (June/2003). An EToTs variation, related to land use and landscape, was detected. The values estimated by remote sensing techiniques, with differences less than ± 0.42 mm/day, are similar those got by using meteorological station data.