In terms of the importance of achieving a successful integrated sustainable management to the agricultural sector within the light of the tangible decrease in Euphrates discharge, this research was initiated with the objective of investigating water demand under different irrigation methods, numerically. Primarily, literature in field of modeling and water scarcity was assembled and scrutinized. Anbar in Iraq was selected to be a case study, to which site visits were carried out and data were assembled. WEAP was selected to be implemented to the case study, where it was calibrated and verified against real data sets. Confident with the calibration process and based on previous studies results, WEAP was applied to the study area. 2010 was taken as the base year and simulations were carried out over a span of 30 years . Two scenarios were considered to calculate the water demand and the unmet demand. The 1 st scenario considered the present condition (i.e. using traditional irrigation methods), while the 2 nd scenario is a virtual condition (i.e. using modern irrigation techniques). The results indicated that the water demand decreased from 5846.59 to 4232.29 MCM, for the 1 st and 2 nd scenarios, respectively (i.e. decreased by 38%). Accordingly, it is recommended to implement modern irrigation methods to achieve successful integrated-sustainable-management in the agricultural sector.