Probability distribution functions of weekly, reference crop evapotranspiration for Pune station of Maharashtra state, India

The study was conducted to know the appropriate probability distribution for weekly ET, values at desired probability levels for Pune station (Latitude 19 degrees 24' N, Longitude 74 degrees 39' E and altitude 514.0 m amsl), Maharashtra State, India. Different ET, methods considered were Penman-Monteith, modified Penman, Hargreaves-Samani, FAO-Pan Evaporation, Blanney-Criddle and FAO-Radiation methods. The probability distribution functions that were fitted to the ET, values are Normal, Log Normal, Gamma, Gumbel and Weibull probability distribution functions. Chi-square test was performed to know the probability distribution of the best fit. The daily climatological data for 20 years (1987-2006) were used to estimate weekly ET, values by different methods. ET, values at 20 %, 60% and 80% probability levels for all the methods using the probability distribution of the best fit. The weekly values at 70 % probability level ET, were determined and presented.