Selecting models for the estimation of reference evapotranspiration for irrigation scheduling purposes.

Lucas Borges Ferreira,Fernando França Da Cunha,Sidney Sara Zanetti,Vassilis G Aschonitis

doi:10.1371/journal.pone.0245270

Lucas Borges Ferreira, Fernando França Da Cunha + Show 2 more

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https://doi.org/10.1371/journal.pone.0245270

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Abstract

Alternative models for the estimation of reference evapotranspiration (ETo) are typically assessed using traditional error metrics, such as root mean square error (RMSE), which may not be sufficient to select the best model for irrigation scheduling purposes. Thus, this study analyzes the performance of the original and calibrated Hargreaves-Samani (HS), Romanenko (ROM) and Jensen-Haise (JH) equations, initially assessed using traditional error metrics, for use in irrigation scheduling, considering the simulation of different irrigation intervals/time scales. Irrigation scheduling was simulated using meteorological data collected in Viçosa-MG and Mocambinho-MG, Brazil. The Penman-Monteith FAO-56 equation was used as benchmark. In general, the original equations did not perform well to estimate ETo, except the ROM and HS equations used at Viçosa and Mocambinho, respectively. Calibration and the increase in the time scale provided performance gains. When applied in irrigation scheduling, the calibrated HS and JH equations showed the best performances. Even with greater errors in estimating ETo, the calibrated HS equation performed similarly or better than the calibrated JH equation, as it had errors with greater potential to be canceled during the soil water balance. Finally, in addition to using error metrics, the performance of the models throughout the year should be considered in their assessment. Furthermore, simulating the application of ETo models in irrigation scheduling can provide valuable information for choosing the most suitable model.

Highlights

Irrigation is a very important practice to ensure good agricultural productions in arid and semiarid areas
Data from two automatic weather stations (2015–2017) of the Brazilian National Institute of Meteorology (INMET) located in the municipalities of Vicosa and Mocambinho, which are located in the state of Minas Gerais, Brazil, were used
NID—total net irrigation depth; Pe—effective rainfall; Deficit (0.50.6)—sum of soil water content deficits in relation to the critical level (50% of TAW, f = 0.5) in the cases of deficits equivalent to 0.50.6, respectively; Excess—excessive irrigation; ETc and Pe—ETc and Pe recalculated using ETo obtained with the Penman-Monteith Food and Agriculture Organization (FAO)-56 (PM) equation

Summary

Introduction

Irrigation is a very important practice to ensure good agricultural productions in arid and semiarid areas. It can contribute to reduce production risks, even in areas with reasonable rainfall levels, and can be used in greenhouse production. Despite its benefits, irrigation should be used properly to avoid excessive or insufficient water application. In this sense, irrigation scheduling plays a key role, allowing one to provide water to different crops according to their requirements [1]. Irrigation scheduling can be performed using different approaches, but it is commonly based on reference evapotranspiration (ETo), which is typically computed using.

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