Estimating and Validating Reference Evapotranspiration Using Weather Data over Northern India

Precise computation of evapotranspiration (ET) is essential for agricultural system modelling, hydrology, irrigation planning, including quantification and scheduling, and water resource management. Additionally, reliable estimations of ET might improve the accuracy of performance indicators related to the water balance in the assessment of irrigation projects. The study presents an estimation of daily reference evapotranspiration (ETO) using the FAO-56 Penman Montheith model and daily weather data from the years 2020 to 2022 over SHUATS, Prayagraj (U.P.). The results obtained were validated with the output of CROPWAT 8.0. Statistical techniques viz. MAE, MBE, RMSE, MRE, Willmot index of agreement (d), ȠNS, PCC, and regression analysis were used to evaluate the performance of the simulation. The lesser values of MAE, MBE, RMSE, and MRE and the highest values of d, ȠNS, PCC, and R2 reveal the closeness of the simulated reference evapotranspiration with that determined by the CROPWAT over the region. The results show the wide applicability to compute the daily ETO using the FAO-56 P-M model for effective management of irrigation water in agriculture.