s.s Eslamian - Professor Department of Water Engineering, College of Agriculture, Isfahan university of Technology, Iran,
a Shirzadian - B.s Department of Water Engineering, College of Agriculture, Isfahan university of Technology, Iran,

Many observations show that the rate of evaporation from the pans have been gently decreasing all over the world in the past 50 years. Based on the data from 35 meteorology stations in Iran from 1985 to 2010, the autocorrelation (ACF) and partial autocorrelation (PACF) of the selected series revealed the seasonal behavior of the monthly evaporation. After the parameters of the models were estimated and the residuals of the models analyzed to be time independent and the normality was checked using Portmanteau lack of fit and nonparametric tests. In this study, the α = 0.05 significant level is used as the significant level for the model building. The multiplicative ARIMA model was fitted to monthly evaporation time series of the stations. The results of the time series modeling showed the mainly decreasing trend evaporation across Iran except margins of the Caspian Sea and several other stations

Climate variability; Trend; Time Series