This study aims to compare the remote sensing (RS) approach and an agro-hydrological model to estimate evapotranspiration (ET) and irrigation water requirement (IWR) in semi-arid region, and the effect of vineyards management and their ages on these parameters. In the study region, after vineyards were classified into three main scenarios based on three vineyards ages (12-15, 15-18 and 18-21 years) and two management approaches (proper and improper management), ET and IWR were determined in each scenario using the Soil-Water-Atmosphere–Plant (SWAP) Model and Surface Energy Balance Algorithm for Land (SEBAL) for the year of 2019-2020 with Landsat8 images. While the accumulated ET calculated with SEBAL was compared with a field water balance, the results showed that without calibration or parameter optimization, the accumulated ET estimated with SEBAL exceeded that computed with SWAP. According to the findings, the most and least RMSE was related to August (1.32) and June (1.26). Analyses of scenarios showed that at the first stage of phonology (bud-break to bloom), the S3 scenario has the most IWR for each pixel (900 m2) by 2.7 m3, and at the second stage (bloom to ripening) and the third stage (ripening), the S1 scenario by 229.5 m3 and 78 m3 has the highest IWR, respectively.