Estimativa da evapotranspiração a partir dos satélites GRACE

Abstract

Many efforts have been made to understand the variability, magnitude and patterns of climatic and hydrological variables. In this sense, the cartographic sciences are established as a tool of fundamental importance in supporting the development of research focused on agriculture and environmental management, mainly in the use of orbital sensors, in the elaboration of studies of great impact, focused mainly on the understanding of variables that influence climate change, such as evapotranspiration, a variable directly related to the hydrological cycle. In this study, the potential of GRACE satellites to estimate evapotranspiration for the hydrographic regions of Amazonas, Paraguay, Paraná, São Francisco and Tocantins-Araguaia was evaluated. Data from the total water storage from GRACE, precipitation data from the TRMM mission and native flow of FLDAS were used to calculate ET. Observations of the ET of the GLDAS model were used as reference guidelines for the validation of the calculated ET. The calculated ET presented overestimates for periods of low water availability. The smallest differences between the calculated ET and the model were in january, a month historically marked by a high volume of precipitation. The highest correlations between the calculated ET and the GLDAS model were for the Paraná and São Francisco basins, with correlation coefficients of 0.57 and 0.53, respectively. The highest correlations between the variables were between dTWS/dt and precipitation, with the indication of significant correlations for all the basins under study. The model proved to be an alternative for qualitative and quantitative evaluation of ET in periods of high water availability.