Hydraulic Simulation of Suggested Barrage on Shatt Al Arab River to Prevent the Salt Intrusion (Al Seeba as a Case Study)

ABSTRACT The Tide River of Iraq, The Shatt al-Arab River is generated by the confluence of the Tigris and Euphrates rivers at the city of Qurna, which is located northern of the Al-Basra Governorate due to climate change and excessive consumption, the flow of the two rivers decreased which resulted in a high percentage of dissolved solids in the river, which caused the river to become salinized as a result of salt wedge intrusion. This study's primary goal is to model the Shatt Al-Arab River's hydraulic response to a proposed barrage in Al Seba to reduce the salinity. In this study, to evaluate the effect of the suggested block dam, a one-dimensional unsteady model was created using HEC-RAS 5.0.7. Four discharge instances, with low and moderate discharges of (20-50-100 and 250 m3/s) and the selected spring tide cycle, were selected. There are four barrage gate cases. (totally open, 50% open, programmed opening, and fully closed) were used in the operation scenarios. The research shows that the examined discharges will significantly affect navigation depths, particularly when gates are programmed to open with stages dropping approximately (0.6 - 1.2) m in comparison to the normal situation. Also, according to the velocity indicators, the barrage's large velocity reduction upstream increased the amount of silt within the river's stream. As a result, a Suggested Barrage is needed on the south reach to avoid salt intrusion.