Relative Comparison of the Local Recalibration of the Temperature-Based Evapotranspiration Equation for the Korea Peninsula

It is well known that local calibration is subject to improving the performance of the temperature-based equation because that calibration includes the influence of the local climate characteristics. This paper evaluates different local recalibrations (the regression-based, one-parameter, and three-parameter methods) of the Hargreaves equation at 21 meteorological stations. The FAO-56 Penman-Monteith is used to describe the control condition against which each calibration method is then assessed. The one-parameter method provides the strength for inland areas, while it presents the worst performance for coastal areas. The regression-based calibration provides slightly better performance for coastal areas. It is true that the difference between the estimates of ETo using the different calibration methods is relatively small and that the difference does not provide the benchmark control that is desirable to demonstrate a significant difference. In relative terms, the regression-based and the three-parameter methods can be an alternative for both inland and coastal areas, giving similar level of accuracy. However, the one-parameter presents may be an alternative only for inland areas. This study can provide guidelines for crop production, water resources conservation, irrigation scheduling, and environmental assessment.