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- Title
ESTIMATIVA DIÁRIA DA EVAPOTRANSPIRAÇÃO DE REFERÊNCIA POR HARGREAVES-SAMANI E AJUSTE DE PARÂMETROS PARA ALAGOAS.
- Authors
CUNHA BARROS, ALLAN; FERREIRA DA SILVA, FERNANDA; VIEIRA ARAUJO, PAULO HENRIQUE; FERNANDES DE MEDEIROS, PEDRO ROBINSON; LELIS NETO, JOÃO ALBERTO
- Abstract
The ETo by Hargreaves-Samani equation is calculated with easily accessible data, air temperature data. Small and medium-sized producers can use it for water management on their farms. Despite the simplicity, some authors recommend adjusting the parameters of the Hargreaves and Samani equation to reduce estimation errors. Thus, the objective of this work is to evaluate the HS equation for different cities in the state of Alagoas, replacing the original equation (PM) and adjusting its parameters. We used a series of historical data from 2006 to 2013 and the treatments were based on the adjustment of three variables. The empirical parameters a, b and c were calibrated through an optimization technique that sought to reduce the sum of the error deviations. The analysis of the quality of the estimates and calibrations was done by calculating the standard error of estimation (EPE), the Willmott's "d" index (d), coefficients of determination (R²) and the confidence coefficient or performance "c ". The results showed good performance of the model in its original form, with an average error of 0.691 mm.dia-, and after the calibration it was possible to reduce the error and 22.47% and to improve the statistical indices. The HS equation, adjusted or not, is an alternative to the estimate of ETo on a daily scale for the cities evaluated in the State of Alagoas.
- Publication
Revista IRRIGA - Brazilian Journal of Irrigation & Drainage, 2019, Vol 24, Issue 3, p527
- ISSN
1413-7895
- Publication type
Article
- DOI
10.15809/irriga.2019v24n3p527-537