No abstract

The erosion on a part of the 4.3km long sandy beach on the right side of Cai river mouth in Nha Trang Bay, Vietnam, which is widely considered as among the world's most beautiful bays, has been observed. This study investigates the mechanism of the shoreline variation based on the analysis of the aerial photographs which cover a long time period. The effect of the hotel which playing the function similar to a jetty in the coastal area has been discussed. The analysis also points out that the variation of the shoreline clearly related to the seasonal variation of wave. The erosion occurs from autumn to winter in every years with the dominant of the northeast monsoon. While, in the remaining periods shoreline is advance. Images from real-time monitoring cameras clearly show the variation process of shoreline from season to season.

Larson et al. (1987) proposed a closed-form solution to describe the development of river delta coastlines owing to sediment supply from the river. This solution is for a beach of infinite extent adjacent to the river mouth. However, in reality, the beach length is always finite due to the existence of man-made structures or headlands. It is, therefore, useful to derive a new analytical solution to gain a better understanding of beach behavior under the effect of boundaries.