Morphological changes in the Tigris River due to Al-Kut Barrage: a comprehensive analysis

From a river engineering perspective, sand bars are often problematic due to their tendency to cause bank erosion and sedimentation, which can obstruct navigation and elevate flood risks. This study investigates the morphological changes that occur downstream of the Al-Kut Barrage (Tigris River in Al-Kut City, Wasit Governorate, Iraq), where variations in discharge and channel form have led to the development of mid-channel and side bars. The cross-sectional data were collected using a Sontek River Surveyor M9 Acoustic Doppler Current Profiler for the year 1992, 2009, and 2022. The flow records were analyzed across three intervals: 1987–1994, 2000–2009, and 2010–2021 to characterize changes in the flow regime. The results of the study indicated a significant decrease in outflows, particularly after the year 2000, with a limited potential for high discharge to return. This hydrological alternation has led to increased sediment accumulation and a rise in the river stage by approximately 0.9 m between the periods 1987–2009 and 2010–2021. Additionally, the cross-sectional area of the river decreased by 12% from 1992 to 2009 and 22% from 1992 to 2022. Dredging activities upstream of the barrage has significantly increased the concentration of suspended sediment and may have accelerated sediment accumulation and morphological changes downstream the barrage over time. In this study, we have emphasized the significance of understanding the morphological response of the Tigris River downstream of Al-Kut Barrage to flow regulation and sediment transport dynamics. The study aims to provide valuable insights into the mechanisms behind mid-channel bar development and sediment accumulation, which can inform future sediment management practices.