Comparative performance of reference evapotranspiration equations at sub-humid Tarai region of Uttarakhand, India

Abstract

In order to estimate reference evapotranspiration (ET0) with the widely accepted FAO-56 PM model especially, in developing countries like India, quality of data and difficulties in gathering all necessary, weather parameters can present serious limitations. Keeping in view, the relevance of precise ET0estimation, an attempt has been made to evaluate, decide and select alternative radiation-based methods to get almost at par ET0 values (from observed climatic data) on the basis of their performance with widely acclaimed FAO-56 PM method as an index for sub-humid Tarai region of Uttarakhand, India. The higher value of Agreement index of ET0 values obtained with FAO24-Radiation method confirms its appropriateness, whereas, value of ET0 method/ET0 FAO-56 PM ratio as 1.00 by Castaneda-Rao method validates its suitability in place of FAO-56 PM at the study area located in the Indian sub-humid region.