Evaluation of Alternative Methods for Estimating Radiation Based Reference Evapotranspiration

摘要

Reference Evapotranspiration (ETfl) plays a key role in simulating hydrological effect of climate change, and a review of evapotranspiration estimation methods in hydrological models is of vital importance. FAO-56 PM model is considered as the standard method for estimation ETQ. As this, method requires large number of weather parameters which could not be easily available at meteorological stations. In addition to the use of complicated unit conversions and lengthy calculations, the reliable qualitydata, time consuming and difficulties in data collection present another serious limitation for this method. Keeping in view, the relevance of precise ET0 estimation, an attempt has been made to estimate and select an alternative method on the basis oftheir performance with widely acclaimed FAO - 56 PM model secondary data for the study on weather parameters for 34 years (1983-2016) was obtained from AICRP on Agrometerology, UAS, GKVK, Bengaluru. The results showed that among all the nine radiation based methods, FAO-24 Radiation method performed well with high accuracy having least values MAE, MAXE, SEE and RMSE. Hence, this method can be recommended for use as an alternative to calculate reference evapotranspiration for GKVK station, Bengaluru Urban District with proper calibration. Besides this, the weather parameters required for use in these methods are comparatively less than that of the standard FAO-56 PM model.