Estimation of evapotranspiration for wheat crop (Triticum aestivum L.)

The use of the empirical model to simulate regional-scale potential evapotranspiration (PET) status helps the growers to attain higher crop water productivity (CWP). There is a need to select the most appropriate model for any region. Under such a situation a study has been planned with the objectives like: (i) Assessment of performance of several popular models to simulate PET and AET under varying moisture supply capacity of the soil, and (ii) Identification of suitable model through statistical validation. Eight empirical models were used to simulate PET values. Names of the models were: Modified Penman (Mod. Pen.), Hargreaves (Harg.), Turc model, Thornthwaite (Thornth.), Blaney-Criddle (Bl-Cri.), Christiansen (Christ.), FAO Penman-Monteith (FAO P.M.) and Open Pan Evaporimeter (Open Pan). Daily value of (i) maximum and minimum temperature, (ii) maximum and minimum relative humidity (RH), (iii) wind speed, (iv) bright sunshine hour, and (v) evaporation during the entire growing period was considered as input parameters. The highest and lowest PET values were simulated by the Turc model and Pan Evaporation, respectively. Turc and Thornthwaite’s model overestimated the AET in comparison to measured values. Overall, the Hargreaves model was concluded to be most suitable and the Turc model least suitable.