Avaliação do desempenho de diferentes métodos de estimativa da evapotranspiração para a Bacia Hidrográfica Taquari-Antas

Abstract

The reference evapotranspiration (ETo) is a very important component of the water balance and its estimation is essential for the execution of agricultural and environmental projects, for water balance studies, irrigation projects and management, climatological process modeling and management planning of water resources. However, due to the large number of meteorological variables employed in this method, several other methods have been used to estimate ETo. This coursework has the objective of evaluating the performance of the different methods of estimation of evapotranspiration in the Taquari Antas River Bacin Development, in Rio Grande do Sul. Therefore, indirect methods were used to estimate the reference evapotranspiration (ETo), being them the Penman-Monteith method that was considered by FAO as the standard method and the methods of Thornthwaite, Hargraves-Samani, Makkink, Blaney-Criddle , Camargo and Jensen-Haise, as well as MODIS sensor images. The data used to estimate the ETo on the four meteorological stations used were obtained through the Agritempo system, which uses data from INMET automatic meteorological stations. The linear regression method was used to analyze the correlation between the ETo estimated by the seven methods, also used the Willmott concordance index and the performance index. The results show that the Blaney-Criddle and Jensen-Haise methods presented the best results, being classified with "optimal" performance. While the methods that presented the worst performances were those of Thornthwaite followed by Camargo's method. The images of the MODIS sensor tend to overestimate the ET values in comparison to all the methods analyzed in this coursework, however it has the advantage of presenting the spatial distribution of the evapotranspirations in the River Bacin Development.(sic)