Performance Evaluation of Five Penman Forms of Models by Means of Lysimetric Evapotranspiration Under Water Stress Environments at New Delhi, India

A global scale has been recommended using the Penman–Monteith method of FAO (56) on reference water evapotranspiration (ETo) calculations or irrigation design, which provides good results under different climatic conditions. In addition to this method, various forms of popular Panamanian equations such as FAO 24 Penman (1977), Kimberly–Penman (1996), and Penman (1948) are widely used throughout the world including India. The evaporation in the Hydrology and Irrigation Committee of the American Society of Civil Engineers has formed a committee recommended by reference standard (standardized Penman–Monteith equation). This method works in a manner similar to that of FAO Penman–Monteith using the short reference station (ETos) used in the present study. The main objective of this study is to assess the performance of these five common forms of Penman forms of the equations established on the daily predictions of the ET indicators under climatic conditions in New Delhi. The ET (ETc) harvest can be obtained using crop factor (Kc). One can develop and use different types of crop coefficients, i.e., single Kc and single Kc with weather correction. The choice of Kc depends on the accuracy required in the ETc accounts. For the evaluation of the performance of five models, the use of selected data from seventeen harvest seasons from 1976 to 2006 of maize (Zea mays L.) was used. Each harvest season requires information on lysimetric ET along with other meteorological parameters and soil moisture monitoring. The statistical indicators used to evaluate the performance were the least squares difference (RMSD), mean bias error (MBE), and t count. From the study, we can conclude that the performance of the Penman–Monteith ASCE and FAO 56 Penman–Monteith is slightly higher than that of the other models under the above-mentioned water conditions, using all four types of crop coefficients.