The research dealt with the effect of Kut Barrage on the geomorphological processes and the natural environment system in the course of the Tigris between the cities of Al-Ahrar and Kut in central Iraq. It was clear from the research the contribution of Kut Barrage in changing the surface runoff system between the front and back of the barrage, as well as changing the type of processes and the prevailing geomorphic forms, as the sedimentation activates the front of the barrage and erosion at its back, which affected the change in the morphology of the river, sediment retention at the front of the barrage, the burial of the bottom and reducing the validity of the stream. This also affects the efficiency of the barrage’s work and coastal erosion in the downstream environment and prevents the formation of the delta in the Arab Gulf, and the high levels and the accumulation of water mass in front of the barrage increases the possibility of activating earthquakes in the presence of tectonically active structures. Environmentally, the barrage affects the rise in the level of groundwater at the front of the barrage and its decrease at the back, and the qualitative characteristics of groundwater and surface water are negatively affected, which is reflected in natural habitats and aquatic life, in addition to the flooding and collapse of banks and soil salinization, which affects the infrastructure of the city and the neighboring agricultural lands, and the research predicts the possibility of the collapse of the barrage and the resulting effects.