PERFORMANCE EVALUATION OF MASS TRANSFER-BASED REFERENCE EVAPOTRANSPIRATION EQUATIONS WITH FAO- 56 PM MODEL AS INDEX AT TARAIREGION OF

In this study, the performance of nine mass transfer-based equations for estimating reference evapotranspiration (ET0) 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 ET0 values obtained with WMO and FAO-56 PM ET0 methods observed on dailyand monthly basis confirms acceptability of WMO method. The ratio of ET0 method/ET0 FAO-56 PM was found best (almost near to 1.00) with Mahringer method