Ecology, Environment and Conservation Paper

SENSITIVITY ANALYSIS OF CLIMATIC PARAMETERS AND REFERENCE EVAPOTRANSPIRATION METHODS: CASE STUDY FROM A SEMI-ARID CONDITION

P.R. Anjitha Krishna and R. Lalitha

Abstract

FAO-56 Penman Monteith (FAO-56 PM) combination formula is recommended as the most accurate method for estimation of reference evapotranspiration (ETo). The major limitation of this method is the requirement of more input data. The present study aims to evaluate selected empirical equations for ETo estimation against the standard FAO-56 PM method and to analyze the sensitivity of meteorological parameters towards standard ETo estimates in order to propose alternate equations for estimation of ETo in Lalgudi taluk, Trichy. The sensitivity analysis of selected methods showed that ETo predicted by Pan Coefficient based methods are well fitted to standard method estimates with R2 values of 0.94, 0.91 and 0.88 for Common pan based method, Pereira model and FAO-24 Pan Coefficient method respectively. The developed regression models based on single or multi parametric approach indicated that combination of minimum temperature (Tmin), morning time relative humidity (RH1), bright sunshine hours (BSS) and wind speed (WV) are more sensitive (R2= 0.99) followed by combination of mean relative humidity (RHmean), BSS and WV (R2=0.97). Local calibration of ETo equations is essential in terms of efficient water management at a location.