Taroko barrier lake stable, unlikely to trigger major debris flow: FANCA

Taipei, Oct. 19 (CNA) Water levels at the Swallow Grotto (Yanzikou) barrier lake in Hualien County's Taroko National Park have stabilized, with inflow and outflow now in balance, the Forestry and Nature Conservation Agency (FANCA) said Sunday.

Huang Chun-tse (黃群策), head of FANCA's Hualien Office, said the overflow from the lake remains steady and that the dam, composed mainly of marble and granite, is structurally stable.

Because of its composition, the dam is less likely to generate large amounts of sediment or mudflows, unlike the barrier lake that formed on the Matai'an River last month and overflowed catastrophically during a storm in September, Huang said.

The new Swallow Grotto lake was formed Friday after a landslide in the upper reaches of the Liwu River, he said.

The water is currently flowing from the west entrance of the Jin Heng Tunnel through the east entrance, and over the Ludan Bridge into Ludan Creek, then rejoining Liwu River, Huang said.

Experts have been commissioned to plan a risk-reduction project that will use excavators to gradually shave the upper section of the dam to improve drainage, he said.

However, heavy rainfall brought by seasonal monsoon winds and Tropical Storm Fengshen has made access difficult, and unstable roadbeds in the area pose safety risks, which have delayed the work, according to Huang.

Meanwhile, the Central Weather Administration (CWA) warned that the current weather system could bring heavy rain to northern Hualien, with up to 250 millimeters expected in the Swallow Grotto area on Monday and as much as 340 mm on Tuesday.

The CWA warned the public to stay away from the lower reaches of the Liwu River and nearby waterways due to the risk of flash floods and landslides.