Utilização do índice de área foliar obtido por sensoriamento remoto para a estimativa da evapotranspiração de referência na bacia do Prata

Abstract

In this work the estimate of evapotranspiration over the region of the Plata Basin, using data of leaf area index obtained from remote sensing, through the MODIS. The method used to obtain the estimated evapotranspiration is known as the Penman-Monteith. This technique uses as well as atmospheric forcing of net radiation, air temperature, relative humidity and vapor pressure, parameters related to vegetation and soil. The method can be written so that vegetation is represented by leaf area index. The atmospheric forcing are derived from South American Land Assimilation System (SALDAS), which is a system of data assimilation system that provide the forcing for the entire South American continent, in a time of three hours and spatial resolution of 0,1º. Monthly maps of evapotranspiration over the La Plata Basin were generated, for the period 2001 to 2004. The monthly averages of evapotranspiration over the basin were compared to estimates made by models based on the calculation of energy balance, and the results showed that the coupling of data from leaf area index to the equation of Penman-Monteith correctly reproduced both the spatial as the seasonal variation of evapotranspiration.