Mechanism of erosion zone formation based on hydrodynamic factor analysis in the Mekong Delta coast, Vietnam

Seven southern most provinces of Vietnam are part of the Lower Mekong Delta (LMD) with approximately 740 km of coastline during the 2016–2020 period faced extensive shoreline erosion. This study analysed the erosion/accretion trends from 2016 to 2020 and determined the mechanism underlying erosion using a MIKE 21/3 toolkit, including the hydrodynamic module (HD), wave spectrum simulation (SW), and sediment transport (MT), focusing on tides, currents, waves, and sediment transport factors. Satellite images (Google Earth), remote sensing images (Landsat 8 OLI/TIRS C1 Level-1), and a combination of hydrodynamic modules were used to evaluate the combined effects of erosion processes. Remote sensing results showed that the erosion speed increased over time. After five years, the coastline of Ca Mau province had an erosion rate of 32.5 m/year in the east and −12.9 m/year in the west. The accretion rate and area gradually decreased from 2016 to 2020. The natural factors that cause shoreline erosion in the MDC are the tidal regime, flow velocity and direction, wave height and direction to shore, and sediment volume. Evaluating shoreline changes using remote sensing technology and validating the results using hydrodynamic models provides a better understanding of the mechanisms underlying coastal erosion and its development and provides a basis for developing a coastal protection strategy. [Display omitted] •The Mekong Delta coast lost land increased significantly in the period 2016–2020.•A modelling approach is presented to clarify the factors affecting erosion.•Tides, currents, waves were identified as the primary causes of erosion.•SSC contributions were identified as the important cause of erosion.•The erosion trend during the southwest was stronger than in the northeast monsoon.