Estimation of actual evapotranspiration based on satellite images using two algorithms Sebal and Metric

There are different methods for evaporation estimation that are applied according to the type of application and the required accuracy. Different remote sensing methods have been in the concern of many researchers recently. It is believed that these methods could provide more accurate results in watershed studies. On the other hand، there is an increasing demand for spatial and temporal evapotranspiration estimation. We used SEBAL and METRIC models to investigate the feasibility of their application for Mashhad watershed and also compared the results obtained from these two models. Surface flux was calculated for each pixel by applying these two models and ASTER images، then actual evapotranspiration was calculated as a residual of the energy balance equation. The results showed that SEBAL algorithm underestimates actual daily evapotranspiration in the order of %8. 398/93 in relation to METRIC model. It was also concluded that both of the models are capable to estimate actual evapotranspiration by considering spatial and topographic conditions and also vegetation cover of the catchment.