Water scarcity is a great challenge and a growing problem for all countries. The present researchfocuses on the rational utilization of water resources with different quality through studying the effects of different parameters on water use efficiency and productivity, the investigation used different parameters such as water resources, sowing dates and water shortage on the amount of water applied, water use efficiency, yieldand net return of barley, in a semi-arid region during growing season 2014-2015. A Split plot layout with three replications was used. Two main plots represent water resources (fresh and brackish water). Sub plots were represented by the sowing dates of: 15^th Dec.,1^st Jan.and 15^th Jan.with water supply rates of: full irrigation, 80% and 60% of amount of water requirements.
The results indicated that, the highest value of irrigation water quantity using brackish water and fresh water were 2285 m³/fed and 2135 m³/fed respectively at planting date of 15 December to add leaching needs and at 100% of irrigation water, while the lowest value for the quantity of irrigation water using brackish water and fresh water at 60% deficit was1237 m³/fed and 1156 m³/fed respectively at the planting date of January 15 in 60% deficit due to the low number of irrigation times. In the meantime, average water use efficiency was 1.28, 1.46 and 1.53 kg/m³ when using 100%, 80% and 60%, respectively, with a yield reduction of 10% and 38% for the use of water 80% and 60% respectively compared to 100%. The average efficiency of water uses when using brackish water was 1.48, 1.65 and 1.64 kg/m³ when using 100%, 80% and 60% irrigation deficit respectively with a decrease in yield of 13%, 51% for the use of fresh water 80% and 60% respectively compared to 100%.