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Limitations of physical and experimental methods for estimating the actual evapotranspiration, ETa, have been rationalized the employment of remote sensing technology to solve the energy balance equation in recent years. In this study, in order to evaluate the SEBS energy balance model in the Gareh Bygone plain, GBP, three stage of calibration, validation and extensive running was performed on Landsat 8 images dated from Oct 2008 to March 2022. Common weather data is gathered from local and the wind from Fasa synoptic stations. In calibration period, 58 images were used for ETa map generation. Water body pixels were extracted from the maps to be used for chak the correlation between FAO penman-Monteith ETo. Model calibration by introducing a new equation for assigning the wind, caused improvent in r2 from 0.66 to 0.76. In validation period, soil water balance data of three farm fields in GBP was gathered to be used as observed ETa. Consumptive water discharge and the volume, returne flow, infiltration depth, soil texture, soil water content, bulk density and capillary rise were the input data for soil water balance approach. Amount of 117771 m3 of observed ETa vs 125452 m3 of modelled ETa showed difference between 3 to 5% inferring a robust agreement.
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