Mechanisms of Formation and Development of a New Island in front of Thu Bon River Mouth, Quang Nam Province, Vietnam

Abstract

 Thu Bon River delta is located at Quang Nam Province in the central region of Vietnam. Cua Dai coastal area has a long coastline from Son Tra Peninsula to An Hoa Cape. This nearly 100 km long coastline plays a significant role in the economic development of the Quang Nam Province. In recent years, coastal erosion along Cua Dai Beach has become severe. On November 05, 2017, The Damrey Typhoon attacked the central region of Vietnam causing an extreme rainfall and river flood in the Thu Bon river basin. About two months after the typhoon, a new island, or as called “Dinosaur Island” was formed at the Cua Dai River mouth. The formation and development of this new island cause a big problem for navigation transportation. Therefore, this study aims to investigate the causing mechanism and the development of the new island. As a result, the formation of the island is due to two processes; shallower sand terrace area due to the river sediment deposition after the flood and the sediment accumulation due to the wave actions. The area of the new island is increasing and it tends to move to the north direction. Besides, the area of the north and south attachment bars are also increasing from the time of new island formation. These findings are really useful information for the local river and coastal authorities to find the best countermeasure solutions to overcome the current situation.