Comparison of the values of potential evapotranspiration estimated through different methods and their relationship

Abstract

Evapotranspiration is very important in water resource management especially in agriculture. Often some farmers use open pan evaporation data for irrigation management under drip and sprinkler irrigation. However, open pan evaporation values are always over estimates because of advection factor. In view of this studies are carried out to find out potential evapotranspiration or reference crop evapotranspiration using empirical formulae. The values derived with this formulae were correlated with open pan evaporation and regression equations were developed. From the analysis it was found that the Christiansen method of estimation of PET values were highly correlated with open pan evaporation in all the three stations representing three agroclimatic zones of Chhattisgarh state. Blaney Criddle equation which considers crop coefficient was not well correlated with open pan evaporation. Hence it is concluded that the Christiansen method of estimation of potential evapotranspiration is best suited for Chhattisgarh state. Using the regression equation the PET values of Christiansen method could be estimated with the help of pan evaporation data.