ESTIMATIVA DA EVAPOTRANSPIRAÇÃO DE REFERÊNCIA PARA TRÊS LOCALIDADES DO ESTADO DA BAHIA

Abstract

The correct management of an irrigation system depends on reliable estimate of reference evapotranspiration (ETo). This paper aimed to evaluate the performance of some empirical equations used to estimate ETo under the climatic conditions of the municipalities of Anagé, Piatã and Ilhéus, located in the Southwest of Bahia State, Brazil. Climatic variables were used for the years 2006 and 2007 obtained through the automatic data collection platform of the Superintendence of Bahia Water Resources / National Institute for Space Research, in which he averaged variables for the two years. To compare the ETo values estimated by methodos of Penman Modificado FAO 24, Radiação, Blaney-Criddlle, Hargreves-Samani, Priestley-Taylor and Turc with the standard method Penman-Monteith (FAO 56) was performed by parameters of regression equation (b), determination coefficient (r²), correlation coefficient (r) estimated standard error (EEP), agreement index (d), index of confidence or performance (c) in daily, three, five and seven days scales. The best methods to estimate ETo for the climatic conditions of the three sites, depending on the indices and parameters studied were by the order: Blaney-Criddle, Penman Modified - FAO 24, FAO 24 Radiation, Turc, Priestly- Taylor and Hargreaves-Samani.