Coastal erosion in the region of Thu Bon River mouth, Vietnam

Abstract: Coastal erosion has increased worldwide during the last decades, mostly due to human activities. Vietnam is not spared, where many places within the country suffer from beach erosion. This report focuses on the region around Thu Bon river mouth in the central part of Vietnam. The beaches next to the river mouth are experiencing severe erosion, especially Cua Dai Beach. The beach is totally eroded in some areas, and the erosion seems to move further away from the river mouth, which will affect the tourist business. There is a lack of previous studies regarding nearshore wave climate and sediment transport along the coast. In the present investigation, field studies and simulations have been carried out to address this lack of knowledge. Three different numerical models have been used to (1) calculate wave climate (EBED), (2) longshore sediment transport (LST Cascade), and (3) shoreline evolution (Cascade). The future shoreline evolution was simulated for 30 years, employing two different scenarios. The first scenario implied no change in sediment transport with the river flow, whereas in the second scenario the sediment transport was reduced to half of its initial value after 15 years. The results show a further retreat of the shoreline on the northern side of the river mouth, which already has an erosion problem. The erosion will move even more to the north in the future, if proper action is not taken.