Abstract
Elongation of a sand spit at Loc An Inlet in the Southern Coast of Vietnam is so remarkable that many resorts and hotels have been built on this newly formed sand spit. The spit elongation is caused by down-drift accumulation of sand introduced by longshore sediment transport. On the other hand, serious erosion of the down-drift sand spit can be observed. In addition, there is a fishing port inside the inlet and the elongation of the up-drift sand spit is causing a problem for navigation of the fishing boats. Due to lacking field data in many coastal zones along the coastline of Vietnam, Landsat and Google earth images from 1988 to 2017 have been utilized for the investigation of the Loc An Inlet's evolution. According to the analysis results, the tip of the up-drift sand spit is shifting with the velocity about 95 m/y while the tip of the down-drift sand spit is retreating at almost the same speed. This indicates that the width of the inlet has remained constant. Longshore sediment transport rate (LSTR) along the up-drift sand spit is calculated as a product of the area change rate of this sand spit and the total depth of closure and berm height. This LSTR shows good agreement with the LSTR calculated by numerical simulation.
