Abstract
On Nha Trang Coast in South Central Vietnam, the retreat of shoreline has become obvious in recent years. However, investigations discussing the coastal erosion mechanism in this area are insufficient. Therefore, a video camera system was installed in this area and started monitoring the shoreline change continuously from May 2013. Based on the camera's image data of over 3 years until August 2016, this study investigated the characteristics of beach deformation on the Nha Trang Coast. According to the video monitoring, the shoreline retreats in winter when the northeast monsoon waves are prevailing, and the beach is recovered in the summer due to calm waves from east or southeast. Then EOF (Empirical Orthogonal Function) analysis was utilized to decompress the dominant processes of shoreline variation along Nha Trang Coast, and found that the first component, which accounts for 93.8% of contribution rate, corresponds to seasonal shoreline change. Moreover, in order to confirm the periodical characteristics of shoreline change, this study approximated spatial and temporal eigenfunctions by using simple linear regression and Fourier series expansion, respectively. It was also found that the seasonal shoreline variation was observed within 350 m of the northern end of this coast.
