Estimates of reference evapotranspiration using empirical equations for a northern area of Peru and northern Amazonas

Evapotranspiration is one of the uncertain parameters in water resources management and irrigation management. Before choosing a particular method to estimate reference evapotranspiration (ETo) in a region, it is extremely important to evaluate the degree of accuracy of the model. The present investigation aimed to evaluate the performance of 05 ETo estimation methods for Bagua province. The meteorological data were taken at the Bagua meteorological station for a period of ten years (2010 to 2019). The method was through the Evaporimeter Tank Type "A"; and they were compared using the determination coefficient (r), coefficients "a" and "b" of linear regressions, standard error of the estimation (SEE), Willmott's concordance index (d), Pearson's correlation coefficient (r) and confidence coefficient (c). The best methods for estimating ETo were: Penman Monteih FAO, Blaney-Criddle - FAO24, Jensen-Haise, Hargreaves and Samani (as a function of sunshine hours and temperature) and Thornthwaite. If only temperature data are available, it is recommended to use the Hargreaves - Samani method (as a function of temperature), which can be used after its equation has been calibrated for the study region. The Penman Monteih FAO, Blaney-Criddle - FAO24, Jensen-Haise, Hargreaves-Samani (as a function of sunshine hours) and Thornthwaite methods are not suitable for estimating ETo in Bagua.