Observed Coastal Morphological Changes Associated with Coastal Engineering Works at Loc An Beach, South East Vietnam

Abstract

Coastal erosion is a common issue and has increasingly become one of the stark challenges along the Vietnamese coastline, in the age of global climate change. Large parts of the coast have already been eroded over the past decades and exacerbated by climate change effects, coastal erosion remains a serious threat to coastal habitats and residents. Many engineering structures have been constructed along the coast to combat erosion, such as in geotubes, sea-walls, jetties, groins, tetrapods, etc., but after construction adverse side effects become visible. This paper focusses on such an engineering project at Loc An Beach, Vung Tau City. At a natural land spit in front of the coast, stabilizing structures have been placed and currently two jetties have been constructed to create a new channel for the navigation of boats to the open sea. Coastal morphology changes are analyzed and described using both satellite images and site observations from before and after the constructions. From the data it is evident that the jetties block the longshore sediment transport, causing downdrift erosion and the jetties cannot fulfill their purpose as sediments need to be dredged to keep the channel open. The results of this analysis are important implications for the planning of future coastal management strategies to deal with coastal erosion; different methods might be considered in the framework of Integrated Coastal Zone Management and in terms of more natural (ecosystem-based) and sustainable approaches for better long-term results.