Estimation methods of reference evapotranspiration (ETo) for Uberlândia -MG

Zilda C De Lacerda,José E P Turco

doi:10.1590/1809-4430-eng.agric.v35n1p27-38/2015

Abstract

One approach to verify the adequacy of estimation methods of reference evapotranspiration is the comparison with the Penman-Monteith method, recommended by the United Nations of Food and Agriculture Organization - FAO, as the standard method for estimating ET0. This study aimed to compare methods for estimating ET0, Makkink (MK), Hargreaves (HG) and Solar Radiation (RS), with Penman-Monteith (PM). For this purpose, we used daily data of global solar radiation, air temperature, relative humidity and wind speed for the year 2010, obtained through the automatic meteorological station, with latitude 18° 91' 66" S, longitude 48° 25' 05" W and altitude of 869m, at the National Institute of Meteorology situated in the Campus of Federal University of Uberlandia - MG, Brazil. Analysis of results for the period were carried out in daily basis, using regression analysis and considering the linear model y = ax, where the dependent variable was the method of Penman-Monteith and the independent, the estimation of ET0 by evaluated methods. Methodology was used to check the influence of standard deviation of daily ET0 in comparison of methods. The evaluation indicated that methods of Solar Radiation and Penman-Monteith cannot be compared, yet the method of Hargreaves indicates the most efficient adjustment to estimate ETo.

Highlights

Agricultural activities require great amounts of water and, facing the matter of reasonable use of this natural resource; efforts have been employed in the development of practices that enable itsEng
One of the essential requirements to estimate the quantity of water necessary for agricultural production is the effective understanding of relations between climate conditions and evapotranspiration
Data was obtained from automatic meteorological station of the Fifth Meteorological District of National Institute of Meteorology INMET, located at the Campus of Federal University of Uberlândia - MG, at latitude 18o 91’ 66’’ S, Estimation methods of reference evapotranspiration (ETo) for Uberlândia -MG

Summary

Introduction

Agricultural activities require great amounts of water and, facing the matter of reasonable use of this natural resource; efforts have been employed in the development of practices that enable its. Eng. Agríc., Jaboticabal, v.35, n.1, p.27-38, jan./fev. In this manner, one of the essential requirements to estimate the quantity of water necessary for agricultural production is the effective understanding of relations between climate conditions and evapotranspiration. The evapotranspiration (ET) is defined as a simultaneous occurrence of two different processes, water evaporation directly from soil surface or from surfaces of free water and transpiration through plant stomas (ALLEN et al, 2006)

Objectives

Methods

Conclusion