Probability Distribution Function for Pomegranate Evapotranspiration : Studies on Probablity distribution function for estimation of reference crop evapotranspiration

The study was conducted to know the appropriate probability distribution for weekly reference crop evapotranspiration (ETr) values at desired probability levels for Solapur, Ahmednagar, Pune and Nasik stations of Maharashtra, India. ETr values were estimated by Penman-Monteith, Modified Penman, Hargreaves-Samani, Pan Evaporation, Blanney-Criddle, and Radiation methods. Based on the root mean square error, Hargraves-Samani found to be the best method for Solapur and Nasik stations and Modified Penman for Ahmednagar and Pune stations. The probability distribution functions selected were Normal, Log Normal, Gamma, Gumbel and Weibull's. Results of probability distribution analysis indicated that, more than one probability distributions were found suitable for finding weekly ETr values. ETr values estimated at 20 %, 60 % and 90 % probability levels in graphical representation for all the methods using the probability distribution of the best fitted were presented. The weekly values at 70 % probability level of ETr were determined and presented for ready reference.