Estimation of Actual Evapotranspiration Based on the Latest Modified Version of the Surface Energy Balance Algorithm Using Lysimeter Data

Evapotranspiration is one of the important components in planning and managing water and irrigation resources. Conventional methods of estimating evapotranspiration use point measurements, but in remote sensing techniques, such as the surface energy balance algorithm, the amount of instantaneous evapotranspiration flux during satellite transit as the remainder of the equation the energy balance is calculated for each pixel. In this study, two common mono-source evapotranspiration models estimated from SEBAL and PYSEBAL were compared with the results of a drainage lysimeter planted with alfalfa in the Qazvin plain. Satellite data were based on data from three sensors, MODIS, LANDSAT-5-TM and LANDSAT-7-ETM, from 2000 to 2003. The results of this study showed that the PYSEBAL model in all three sensors with RMSE (0.45, 0.46, and 2.02 mm/day) respectively had better performance than the SEBAL model. Also, the studies performed from the three sensors showed that the MODIS sensor with standard error value (0.15 mm / day) and correlation coefficient (0.98) compared to the two ETM and TM sensors with correlation coefficient values (0.97 and 0.53), standard error (0.17 and 2.26 mm/day) as well as higher spatial resolution have been able to produce better results.