Performance Evaluation of Mass Transfer-Based Reference Evapotranspiration Equations with FAO- 56 PM Model as Index at Tarairegion of Uttarakhand, India

In this study, the performance of nine mass transfer-based equations for estimating reference evapotranspiration (ET ) was statistically analyzed in comparison to widely accepted Food and Agriculture Organization Penman-Monteith method (FAO-56 PM) model forsub-humid Udham Singh Nagar district of Uttarakhand. The higher values of Agreement index, coefficient of determination, correlation coefficient; and lowercalculated values of Root Mean Square Error, Mean Bias Error, Maximum Absolute Error, Percentage Error and Standard Error of Estimate between ET values obtained with WMO and FAO-56 PM ET methods observed on dailyand monthly basis confirms acceptability of WMO method. The ratio of ET method/ET FAO-56 PM was found best (almost near to 1.00) with Mahringer method.