| dc.description.abstract | The Mekong Delta shoreline has suffered complex variations that induced severe land loss and infrastructure destruction, impacting eco-tourism and coastal aquaculture areas. Therefore, it is necessary to understand the accretion and erosion mechanisms to introduce appropriate strategies to protect the coasts. This research aims to investigate the shoreline variations in the Mekong estuary zones. The study utilized Landsat satellite images and Delft3D software to estimate shoreline change rates and develop a hydrodynamic model to evaluate shoreline variations behavior. The results show that from 1988 until 2021, the maximum erosion rate was 33.9 m/year, and the maximum accretion rate was 86.3 m/year in segment 3. The erosion mainly occurred in the convex shoreline, while accretion frequently occurred in the concave shoreline. The hydrodynamic model performance generally is good in predicting the water levels. An Thuan and Ben Trai stations gave excellent results over 0.8, indicating high agreement between simulated and observed water levels. Binh Dai and Tran De stations, which produce good results, all metrics are over 0.69, except for the Binh Dai station′s NSE metric, which gives reasonable results (0.54 – 0.64). Vung Tau station is adjacent to the boundary, and the metrics are good, except the NSE is poor. The model results revealed that the river flow and sea dynamics vary by season. In the dry season, when the river flow is low, under 7,000 m3/s in a day, the northeast monsoon makes the wind blow in the northeast-southwest direction with the speed of 5-10 m/s and 10 - 15 m/s dominantly, causing impacts on the vegetation and waves, tides, in this area, leading to them directly attacking the convex shoreline causing erosion. Sea dynamics push the fresh-saltwater interface from the northeast to the southwest and are located near the shoreline. In the wet season, river water discharges into the sea up to 22,000 m3/s in a day, and the southwest monsoon makes the wind blow from southwest to northeast with the speed of 5-10 m/s. Thus, sea dynamic factors combined with abundant river flow and sediment during the wet season generated suitable conditions for sediment deposition in the concave shoreline and developing mangrove marsh and tidal flat. Based on the shoreline variations and hydrodynamic model result, the shoreline change mechanism in this area might be impacted by the shoreline position, seasonal variations of hydrodynamics, and the shoreline sediment characteristics. Eventually, the study findings can be used as a reference for developing adequate strategies for protecting coastal areas. | en_US |