estimation of crop actual evapotranspiration using sebal algorithm (case study: khoramdareh region at zanjan province)

accurate estimation of crop evapotranspiration (etc) plays an important role in improving the water useefficiency (wue) and water management. due to the presence of different types of coatings plant in large areas, the accurate calculation of the water requirements by conventional methods is elusive or impossible. remote sensing methods are becoming attractive to estimate crop evapotranspiration, as they cover large areas and can provide accurate and reliable estimations. present study estimates the actual evapotranspiration of corn and alfalfa cover at khoramdareh region using remote sensing and meteorological data. surface energy balance algorithm for land (sebal) and landsat 8 images were utilized to determine actual evapotranspiration of corn and alfalfa covers. the obtained results were compared with the results of the pm-fao56 model. the results showed that two models had good agreement with each other. values of rmse for the estimation of actual evapotranspiration of corn and alfalfa was found respectively, 0.92 and 1.25 mm/day. the determination coefficient (r2) for corn and alfalfa was respectively 0.89 and 0.83 respectively. the results showed that the sebal algorithm estimates the actual evapotranspiration of corn and alfalfa crop respectively less and more thanpm-fao56 model.