Big waves have washed away about 8ha of public beach in Cua Dai, 5km east of the ancient town of Hoi An, in recent weeks.
The waves now threaten to undermine dozens of resorts in the area.
Head of Hoi An city's natural resources environment office, Nguyen Van Hien, told Viet Nam News yesterday that an area land about one kilometre long and 80 metres wide had been eroded.
Two years ago, the area was considered one of the most beautiful sites for tourists to relax and swim.
"Waves now crash onto a plantation of coconut trees along the beach," Hien said. "There are no good and safe places for people to sunbathe or swim."
He said city authorities had tried to stem the erosion with sandbags and rocks, but little was achieved because of a lack of funds and slow work.
Rising sea levels and changes to the river flow in the Thu Bon River estuary have been eating away at Cua Dai beach for many years, according to Hien.
Quang Nam Province has allocated funds to build a 1.5km embankment to help protect the most heavily damaged section of the beach.
A loan of VND7.5 billion ($357,000) has been made to plant 140ha of Nipa palm along the Thu Bon river.
VNS/VNN