This paper describes the use of a remote sensing technique, the Surface Energy BalancernAlgorithm for Land (SEBAL), to assess actual evapotranspiration across Kobo valley irrigationrnproject. The SEBAL model was applied to the Landsat 7 ETM+ image corresponding tornDecember 05, 2003 to produce estimates of ET at 30Ã—30m resolution. The actualrnevapotranspiration (ETa) was integrated for 24 hours on a pixel-by-pixel basis from therninstantaneous evapotranspiration (ET). SEBAL ETa estimates vary from 0 to 4.86 mm/day overrnthe image. Lowest ETa was observed for barren fields and highest for water bodies. ETa forrnvegetative areas ranges 3.5 to 4 mm/day. Irrigated areas, drip and sprinkler irrigation systems,rnappear to evaporate with average rate of 1.8 mm/day. Penman-Monteith reference croprnevapotranspiration ET0 on the same day was found to be 4.5 mm/day at the meteorologicalrnstation. During the dry season, actual evapotranspiration increases with the availability ofrnmoisture in the soil instead of the temperature gradient. The performance of the irrigationrnsystem for the command area (September to January) was determined according to 5 indicators,rnnamely overall consumed ratio (OCR), relative water supply (RWS), depleted fraction (DF),rncrop water deficit (CWD), and relative evapotranspiration (RET). Potential and actualrnevapotranspiration parameters used in determining these indicators were estimated according tornthe SEBAL (Surface Energy Balance) method using Landsat ETM+ image. Seasonal averages ofrnthe irrigation project calculated from the results were 0.55, for OCR; 1.23 for RWS; 0.29 forrnDF; 42.44mm/month for CWD; 0.43 for RET. According to the seasonal average values of allrnthe performance indicators, the irrigation performance of the area is usually poor and only thernoverall consumed ratio indicator is within the range of acceptability. Thus, performancernindicators showed that less irrigation water was supplied to the area than was needed.rnKeywords: Performance indicators, performance assessment, evapotranspiration, SEBAL,rnremote sensing