Hydrodynamic and Sediment Transport Studies of Gorgan Bay (Case Study: Khozeini Channel and Investigation of Jetty’s Role in Reducing Active Sedimentation After Channel Dredging)

Gorgan Bay is one of the greatest economic and ecological areas in Iran and is used as a recreational and fishery center by the region's residents. This bay connects to the Caspian Sea through two channels, Ashuradeh and Chapoqli. The hydraulic connection of Gorgan Bay with the Caspian Sea greatly impacts water recirculation and aquatic life in this region. As a result, the decrease in the water level of the Caspian Sea, and the disruption of the hydraulic connection between them have caused problems with the water quality in the bay in recent years. Several solutions have been proposed to solve these problems, including dredging the Ashuradeh and Chapoqli channels, reopening the Khozeini channel, and transferring water by pipeline to the west of the bay. Although the mentioned actions can increase the volume of water exchanges and reduce water retention time, each action requires careful consideration to estimate its long-term effectiveness. Considering the possibility of re-sedimentation in each of the above channels, studying sedimentation and erosion patterns in this area can help determine the shape, depth, and duration of dredging and the economic justification of jetty construction at the channels’ mouth. Hence, in this study, the amount of sediment load beside the patterns of erosion and sedimentation after dredging the Khozeini channel as well as the effects of implementing jetties have been determined using Mike 21. Based on the simulation results, the area has an active sedimentary pattern that can impact the bed level inside the channel. These effects can be reduced at the channel’s mouth by constructing two jetties on its sides.