Hydropower dams on the Vu Gia – Thu Bon River system has hindered sedimentation downstream, causing severe erosion that could wipe out a popular beach in Hoi An town, experts warn.
“Climate change with a sea-level rise of 30cm is not the only reason for the current speed of erosion of Cua Dai Beach,” Vu Thanh Ca of the Scientific Research Institute of Sea and Islands said.
“The major cause is a significant change in sedimentation in the Vu Gia - Thu Bon river system that flows into the East Sea near Cua Dai,” Tuoi Tre (Youth) newspaper quoted him as saying.
At many conferences to discuss prevention of erosion in Hoi An, a UNESCO heritage site that has suffered serious coastal erosion since last October, scientists have identified upstream hydropower dams and sand dredging in the river as the problem.
According to the Quang Nam Province People’s Committee, the Vu Gia Thu Bon has 42 hydropower dams.
“There has been a surge in dam building in the past three years, leading to a significant reduction in sediments being washed down to the estuary in the beach town of Hoi An,” Ca said.
Le Cong Sy, an official in the town's Cua Dai Ward, said the sea has moved 150 meters inland in the past eight years and at an increasing pace, reaching a further 30 meters inland in a single month last October.
A total of six resorts on Cua Dai Beach are at risk of falling off into the advancing sea, with two recently completed resorts failing to open due to the erosion.
Professor Hitoshi Tanaka of Tohoku University in Japan also said lack of sediments from upstream is the major reason, because erosion began from the estuary before spreading to the coastline.
Quang Nam authorities have granted licenses to 15 companies to mine sand from the Vu Gia – Thu Bon River. Another 40 have applied for licenses.
Ca said there should be a complete ban on sand mining in the river and construction of dikes along the coast.
Tran Thanh Tung, a lecturer at the Hanoi-based Irrigation University, suggested replacing the sand in eroded areas and planting protective forests.
Nguyen Su, the outgoing chief of Hoi An Party unit, said human elements had caused erosion.
“If it loses 7km of Cua Dai Beach, Hoi An will be no longer an attractive tourist destination.”