EVALUATION OF METHODS TO ESTIMATE POTENTIAL EVAPOTRANSPIRATION IN NORTHERN RECIFE-PE

Abstract

Evapotranspiration is one of the key factors determining efficiency of irrigation management. In the absence of climate data, the choice of a model for its estimation should be strictly criteria based. In this study the performance of nine methods of estimating potential evapotranspiration (ETp) in the northern Recife/PE were evaluated, using the data collected from a weather station and “Class A” pan located in the Federal Rural University of Pernambuco during the period of 2009 and 2011. Estimated data were correlated by linear regression, using FAO-Penman-Monteith method as standard. Performance of methods was based on correlation coefficients “r”, agreement “d” of Willmott and the performance index “c”. The best ETp estimates were obtained by the methods of solar radiation, Camargo, and Makkink and Priestley-Taylor, all with “c” index between 0.80 and 0.98, considered good to best. The methods of Hargreaves-Samani and Blaney-Criddle had “c”index in the range of 0.6 to 0.89, varying according to the mean of one, three, seven and ten days. The methods “Class A” pan, and Linacre had lowest “c” indexes varying between 0.40 and 0.70.