A Comparative Relation of Distinct Reference Crop Evapotranspiration Models for Southern Brazil

Abstract

Water is one of the main limiting factors for achieving high productivity in agriculture. The hydric requirement of plants is fundamental for the dimensioning of the irrigation system and contributes to the better use of hydric resources. Moreover, the accurate computation of this element is essential for water management in agricultural systems. Nonetheless, due to the heterogeneity of different evapotranspiration estimation methods, the performance of its calculation can be considerably compromised. Accordingly, the aim of this study was to compare the methods for estimating reference evapotranspiration (ETo) by Benevides & Lopes, Camargo, Hargreaves & Samani, Jensen & Haise, Linacre, Makkink, Penman, Priestley & Taylor, Tanner & Pelton, and Turc, with the FAO-56 Penman-Monteith standard method, to evaluate the performance and accuracy of equational models. Furthermore, data from an automatic weather station belonging to the Brazilian National Institute of Meteorology (INMET), located in Palmeira das Missões, Rio Grande do Sul, Brazil, from January 1, 2020, to January 1, 2021, were used. Comparative statistical methods were utilized to express the accuracy of the models and indicate the most appropriate equations for the conditions of the selected location. Cluster analysis and Principal Component Analysis (PCA) were applied. For Palmeira das Missões, the model proposed by Hargreaves & Samani indicated the best results and was characterized as the most appropriate alternative to estimate the ETo more accurately. The method indicated the most favorable results for R2 (0.9890), d (0.9253), and r (0.9944). Furthermore, cluster and PCA analyses expressed the behavior of relationships between different mathematical models and meteorological parameters in relation to the ETo determination.