In order to get reliable qualitative and quantitative information about a potential of waterrnresource in a catchment it is important to assess and evaluate the spatial and temporal variationrnof actual evapotranspiration by applying SEBS algorithm and SWAT hydrological model andrneventually compare with MODIS ET. This is one of the motivations for evaluating the spatialrnand seasonal dynamics of actual ET for the Gilgel Abay catchment using energy balancernalgorithm and hydrological model.rnSpatially distributed actual evapotranspiration (ETa) values were estimated using Surface EnergyrnBalance System (SEBS) approach and the Soil and Water Assessment Tool (SWAT). The inputrndata for SEBS and SWAT were acquired from different sources with different spatial andrntemporal resolutions. The dynamics of ETa was assessed only for the selected dry years (2009)rnand wet year (2005 and 2007). Moreover, the analysis was based on the nine selected days ofrnthose years having a cloud cover less than 30%. The estimated ETa values were also comparedrnwith MOD16 ET at sub-catchment scale.rnSEBS based estimated daily actual ET eventually were compared with MODIS ET and SWATrnactual ET estimates to assess the temporal and spatial variability in the catchment. The resultrnshowed that the mean value of SEBS daily actual ET during those days reached up to 5.9 mm/drn(Jan-01-2005), 5.5mm/d (January 10, 2007) and 5.1 mm/d (March 12, 2007). In distinction as itrnobserved from the results during wet season days the SEBS estimated actual ET is relativelyrnlower and highly variable spatially. The mean actual ET for day of the year [DOY] 253- 2009 isrn8.8 mm/d, DOY 336 - 2007 is 5.8 mm/d and DOY 330- 2009 5.1 mm/d which shows the spatialrnvariability resulted due to heterogeneity of the vegetation cover during the wet season. Similarly,rnthe long-term mean annual actual ET derived from previous hydrological studies using SWATrncompared well with MODIS ET over the terrestrial part of the catchment. The evaluation of thernwet season actual ET from 2000-2010 from MODIS and SEBS was compared with SWAT andrnthe result showed that a good correlation. Thus, overall MODIS ET product showed goodrnagreement with results from the SWAT models both in magnitude and spatial variability