Modelos empíricos para estimativa da evapotranspiração de referência para Patos - PB.

Abstract

Empirical models for estimating reference evapotranspiration for Patos - PB. Evapotranspiration is one of the basic components of the hydrological cycle and can be conceptualized as the amount of evaporated water originating from the soil or the vegetal individual plus the portion transpired by the latter, its determination can be carried out quickly by indirect methods. The standard Penman-Montheith method is the standard adopted by FAO for the calculation of reference evapotranspiration, but it requires the use of many climatic variables that are not always available in meteorological stations. Number of variables and are compared with the standard model. The objective of this research was to compare the reference evapotranspiration (ET0) estimated by different empirical models with the FAO-56 Penman-Montheith method, as standard, under the climatic conditions of the Patos-PB region. The climatic variables used come from the collection of the Conventional Meteorological Station and was made from a series from January 2003 to August 2015. The evaluation of the ET0 estimates was based on the correlation coefficient (r), coefficient of determination (R2 adjusted) , Standard error of estimation (EPE), concordance index (d), and the coefficient of performance "c", which is the most used parameter in the evaluation of models to the standard method. According to the results, the Benavidez-Lopes model presented median classification for daily data. For the models of Hargreaves-Samani, Turc, Ivanov and Hamon, there was an underestimation, presenting a classification between bad and suffering, and in the others, namely: Benevides-Lopes, Kharrufa and Linacre, overestimation occurred, with a medium to poor classification The FAO standard for the Patos-PB region. In view of these results, it can be concluded that only the Benavidez-Lopes model can be used with reservations, in the daily period.