Experts warn Taroko barrier lake dam unstable

專家示警太魯閣堰塞湖大壩不穩定

TAIPEI (Taiwan News) — Experts are warning that a natural dam formed by a landslide in Hualien County’s Taroko Gorge has become unstable due to rising water levels and seepage.

According to the Forestry and Nature Conservation Administration’s (FNCA) Hualien Branch, the landslide-created dam across the Liwu River is showing signs of weakness as seepage increases and water levels continue to rise. The barrier lake currently holds about 2.7 million tonnes of water, per CNA.

Officials said that overflow from the nearby Jinheng Tunnel and seepage at the dam’s base have slowed the rate of accumulation, but experts predict the dam could fail soon due to overflow or seepage, especially if heavy rain continues.

Li Meng-yen (李孟諺), chief coordinator of the Forward Coordination Post of the Central Emergency Operations Center, said Saturday afternoon that the river channel below the dam is wide enough to accommodate overflow, reducing the immediate risk downstream. However, residents in nearby areas have been evacuated and advised to stay away from the river channel.

Li noted that the landslide material forming the dam consists mainly of marble and granite fragments with low silt content, unlike the Mataian Creek barrier lake, which reduces the risk of catastrophic flooding. Teams from National Cheng Kung University and National Yang Ming Chiao Tung University have been dispatched to assess the site’s stability.

The FNCA and the Directorate General of Highways have begun building an 80-meter access road from the old Provincial Highway 8 to the Yanzikou Trail to allow heavy machinery to reach the dam for excavation.

Li said that frequent rockfalls and the area’s steep terrain have slowed construction, with safety checks required before excavation can begin. Officials estimate the access road will take about three days to complete.

The landslide dam measures 54 meters in height, with a total volume of roughly 400,000 cubic meters of rock and a water storage capacity of 2.7 million tonnes, about 0.2% of the capacity of the Mataian Creek barrier lake.