Comparison Between Estimation Methods of Reference Evapotranspiration in Bom Jesus ​​da Lapa, Ba

Abstract

Among the reference evapotranspiration (ETo) equations, the FAO-56 Penman-Monteith (PM FAO-56) model is considered the most accurate, but this model requires a greater amount of meteorological data. On the other hand, there are other methods that require fewer variables and have shown good precision according to the location. The objective of this work was to evaluate the efficiency of four methods for estimation of daily ETo, comparing them with FAO-56 PM equation in Bom Jesus da Lapa, Bahia, Brazil. To do so, a dataset from 2010 to 2017, acquired at the National Institute of Meteorology (INMET), was used. The models were analyzed by means of statistical indicators: Willmott’s concordance index, root mean square error (RMSE), mean bias error (BIAS), coefficient of determination “R²”, correlation coefficient “r” and coefficient of confidence “c”, in addition to the classification of the coefficient of confidence. The results obtained show that Hargreaves and Samani equation was the only method classified as “good” and is recommended. While the models of Camargo, Priestley and Taylor and Benevides and Lopes are not recommended to calculate ETo in the municipality.

Reference crop evapotranspiration in distinct agricultural regions of Southern Brazil: a comparison of improved empirical models

“…Generally, the Hargreaves & Samani (736.4 mm) and Linacre (1262.6 mm) models were those ones that most underestimated ETo. The Benevides & Lopes (2309.5 mm) and Makkink (1947.8 mm) According to the parameterization of ETo when compared to the standard FAO56 method, studies show that methods such as Benevides & Lopes tend to overestimate the ETo values, making it an inefficient alternative for safe ETo estimates (COSTA et al, 2020). Nevertheless, studies showed that the Benevides & Lopes model can be an alternative to the FAO56 model when compared to other models that use T air .…”