Modeling of Hydrodynamic Regimes for the Thuan An Estuary

Abstract

Located in the southeast of Hue city in Thua Thien Hue province, Thuan An estuary plays a crucial role as a waterway and flood drainage pathway for the Huong River. Importantly, the morphology of the Thuan An estuary has been subjected to continuous change during monsoon seasons with the process of sediments in the estuary and erosion along the northern and southern coasts. Remarkably, the process of sediments directly impacts flood drainage and navigation along the waterway, as well as the sustainable development of Thua Thien Hue marine economy. Therefore, the goal of this study is to insightfully provide hydrodynamic regimes using a Delft3D model combined with ArcGIS software. The results showed that the estuary is wave-dominated lowland coasts. The coastal barrier is formed from sand that is transported along the shoreline by wave-driven longshore currents. During the northeast monsoon, river flow is significantly small, tidal currents combine with longshore currents by waves to form a strong longshore current with direction from northeast to southwest. Whereas, during the southwest monsoon, the sandbar extending from the southern side expands northward, leading to sedimentation accumulation at the river mouth channel. Specifically, a sandbar is formed at the river mouth with an accumulation of up to about 0.8 m.