Comparison of the Values of Potential Evapotranspiration Estimated through Different Methods and their Relationship

In the present study, six empirical methods, namely, Modified Penman, Blaney Criddle, Christiansen, Thornthwaite, Open pan, Turc and FAO penmanmethod are computed using the daily weather data for the period 1981–2012 (32 years) was collected for three stations in Chhattisgarh state representing 3 agroclimatic zones. It is found that FAO Penman method is the best method for estimating potential evapotranspiration. The comparison of ETo estimates was done based on the weekly averages of PET using correlation coefficients and regression methods throughdifferent methods. At Ambikapur the highest correlation coefficient between FAO Penman and Modified Penman method 0.998 andlowest inbetween Christiansen and Blaney criddle method 0.918. At Jagdalpur and Raipur also having the highest correlation coefficient between FAO penman and Modified penman method 0.999.and lowest correlation coefficient in between Christiansen and Turc method 0.85 or 0.84. Regarding regression with Open pan evaporation, highest R² values are with Modified Penman and Christiansen methods at Ambikapur while at Jagdalpur and Raipur highest R² was with Christiansen method. Thus the open pan evaporation can be estimated by Christiansen method.