Estimating of Crop Coefficient and Actual Evapotranspiration of Corn Using LANDSAT8 Images (Case Study: Sarab Nilufar Plain in Kermanshah)

SEBAL model is nowadays among the algorithms used by researchers to estimate evapo-transpiration and crop coefficients by satellite images. In this study, the ability of the SEBAL model to determine the corn actual evapotranspiration and crop coefficient was evaluated for Sarab Nilufar Plain located in Kermanshah Province. For this purpose, satellite images from Landsat 8 were processed in three days of 07.22.2014, 08.07.2014 and 08.23.2014 were used. Actual–evapotranspiration was calculated using satellite images based on the surface energy balance equation (SEBAL model) and required meteorological data. Moreover, the potential evapotranspiration was computed for corn using Penman-Montieth method and then using the calculated data from SEBAL method, the crop coefficient values were determined for the above mentioned days. Finally, the evapotranspiration values by the SEBAL model (predicted values) were computed for corn as 7.11, 6.9 and 5.16 mm/day and crop coefficients values were obtained as 1.09, 1.33 and 0.87, respectively.