Potential evapotranspiration is an important input for simulations of the hydrological cycle.Deficit and wind velocity (Singh et al., 1997).In 2000, Xu and Singh compared eight energy methods, including the ones described
By Turc (1961), Makkink (1957), Jensen and Haise (1963), Hargreaves (1975), and Doorenbos

And Pruitt (1977), Bordne and McGuinness (1972), Abtew (1996) and Priestley and Taylor

(2005).Xu et al. ana have combined seven types of temperature-based methods in 2001; the results show that the Blaney-Criddle
Method, Hargreaves method and Thornthwaite method have better results for simulation





Beyond the others.He found that: the application of the Penman-Monteith method, Makkink, Priestley and Taylor and Abtew were better than the other methods Many researchers have proposed some temperature-based methods under limited climate data conditions.The effect was analysed in 1997 by Gardelin and Lindstrom

Different possible methods for calculating the evapotranspiration on simulation accuracy

The Model HBV.They found that the Penman process, corrected with temperature, improved the
Precise simulation; nevertheless, the results obtained with the Priestley-Taylor method
Had been better.The possible methods for estimating evapotranspiration can be divided into the energy-based methods,

Methods based on temperature and mass transfer, depending upon their mechanisms
The energy-based approach uses the principle of energy balance to estimate future evapotranspiration.(1972).