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

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.

Water Overlapping Area for The Arrangement of Field’s Sprinkler Irrigation

“…The overlapping area for half blade is calculated by (5) Hence, the overlapping area for one horizontal blade is defined as (6) where the value is double the area of MNP. Since the distance between each sprinkler at length and width are different, so to calculate the overlapping area for one vertical blade, d is substituted by Hence, the overlapping area for one vertical blade is defined as (7) From Eq.…”

“…Although there are various benefits in irrigation, an efficient management system is needed to avoid excessive or insufficient water consumption [5]. Therefore, irrigation scheduling plays an important role, which allows one to provide water for different crops according to their needs [6].…”

Spatial distribution of the trends in potential evapotranspiration and its influencing climatic factors in Iraq

“…Accordingly, PET is imperative for determining irrigation scheduling and crop water requirements and estimating the water budget (Allen et al, 1998, Zhang and. PET is also essential for computing the actual evapotranspiration, representing the amount of actual water quantity removed from a surface, which is necessary for evaluating agricultural water demand (Khaydar et al, 2021, Ferreira et al, 2021. It is also required to estimate the aridity index and help understand the regional drought and dry conditions (Um et al, 2020).…”