MÉTODOS EMPÍRICOS PARA ESTIMATIVA DA EVAPOTRANSPIRAÇÃO DE REFERÊNCIA NO ESTADO DO RIO DE JANEIRO

Abstract

The use of rationally water has become increasingly important in recent years. Evapotranspiration is an important variable in the hydrologic cycle in which their knowledge is essential for irrigation management. The objective of this study is to evaluate the performance of the methods Priestley-Taylor, Hargreaves-Samani, Thornthwaite and Camargo, compared with the Penman-Monteith, in the estimation of reference evapotranspiration in three municipalities in the Rio de Janeiro State. Climate variables were used for the period from 01 January 2011 to 31 December 2013 from automatic weather stations INMET in the cities of Paraty, Petrópolis and Campos dos Goytacazes. Daily and monthly time scale were evaluated using the methods. For the comparative analysis between them and the standard method was performed simple linear regression analysis and calculations of statistical indexes: Pearson's correlation coefficient (r), index of agreement of Willmott (d) confidence index of Camargo performance (c). In the studied scales, methods of Priestley-Taylor and Hargreaves-Samani outperformed the other methods evaluated. The Priestley-Taylor method was more reliable in the estimation of the reference evapotranspiration in Paraty and Campos dos Goytacazes, and Hargreaves-Samani method for Petrópolis.