Validação do modelo SAFER na estimativa da evapotranspiração da cana-de-açúcar

Abstract

Methods that can determine the water balance of cultures from satellite images prove to be very useful because they can provide its determination in large areas with high heterogeneity. The aim of this study was to compare the real evapotranspiration (ETr) estimation method obtained by SAFER (Simple Algorithm for Evapotranspiration Retrieving), to the climatological water balance and the soil water balance in order to validate the proposed methodology as an alternative to traditional methods. The study was conducted in Santo Antônio de Goiás – GO, Brazil, in a non-irrigated area with 100 hectares, planted with sugarcane (CTC-4 variety). The ETr was estimated using Landsat 8 (OLI / TIRS) satellite images and the results compared to the soil water and climate balance in the period from May toAugust 2015. In general, the results estimated by SAFER corroborated those of traditional methods, estimating ETr values of 0.70 mm dia-1, on average, above estimation values obtained with the soil water balance and 0.48 mm day-1 for the climatic water balance. The evapotranspiration estimation method using remote sensing and the agro-meteorological model SAFER can be used to estimate actual evapotranspiration (ETr) of sugarcane in the Cerrado region, using the adjustment ETr = 0.87*ETSAFER – 0.51 for the soil water balance and the adjustment ETr = 0.92*SAFER - 0.36 for the climatological water balance.