202508/20
To improve the monitoring capabilities of the Matai’an River landslide dam in Hualien, with the assistance of the National Airborne Service Corps under the Ministry of the Interior (MOI), a team of nine personnel from the Hualien Branch of the Forestry and Nature Conservation Agency (FANCA Hualien) and the Disaster Prevention Research Center of National Cheng Kung University successfully installed a water gauge by helicopter at the top of the landslide dam today (08/20). According to the latest data transmitted by the water gauge, currently the dam surface is 40 meters below the overflow point. In the future, the water gauge will be able to provide relevant departments and the Hualien County Government with more precise warning information, which will serve as an important basis for the evacuation of downstream residents.
The Matai’an River landslide dam is located in Wanrong Township. Since its formation, the FANCA has held two expert consultation meetings, where representatives from different units were invited to jointly discuss various pressure relief solutions, including lowering the height of the dam, blasting the dam body, and siphon pumping. These units included the Office of Disaster Management (ODM) and the Public Construction Commission (PCC) under the Executive Yuan, the National Science and Technology Center for Disaster Reduction (NCDR), the Water Resources Agency (WRA) under the Ministry of Economic Affairs (MOEA), the Agency of Rural Development and Soil and Water Conservation (ARDSWC), and the Ministry of National Defense (MND). However, the remote location of the landslide dam and the lack of road access, as well as the soft soil and rocks of the dam body, and ongoing landslides in the surrounding area all pose difficult restrictions. In addition, the risks of typhoons, heavy rainfall, and earthquakes all need to be taken into consideration. All of these factors make machinery access to the construction site very difficult and highly hazardous. Experts estimate that it may not be feasible to use engineering solutions within a short timeframe to deal with the problem. Therefore, the primary response strategy currently focuses on strengthening monitoring and alert capabilities, as well as downstream disaster prevention and mitigation measures.
FANCA Hualien has installed rain gauges, concentration meters, and CCTV surveillance cameras around the dam area. These are linked to the downstream water level station and surveillance images of the WRA to keep abreast of the latest conditions at all times. However, due to the steep terrain of the dam crest, the lack of access roads, and mountainous climate conditions, the installation of the water gauge had proven challenging. Today, with the support of the National Airborne Service Corps, the installation of the water gauge at the top of the dam was finally completed successfully.
According to today’s statistical modeling projections, the current surface area of the landslide dam is about 82 hectares, with a water storage volume of about 48 million tons. This represents 53% of the maximum capacity (about 91 million tons). Barring heavy rainfall, it is estimated that the dam may overflow in early October.
Director Huang Chun-Tse of FANCA Hualien pointed out that the installation of the water gauge significantly enhances monitoring accuracy. Combined with the existing rainfall data, a more comprehensive monitoring model can be established to scientifically track rising water levels and overflow risks. These data will serve as an important basis for disaster prevention. Once the water level or cumulative rainfall reaches the warning threshold, FANCA Hualien will immediately notify the Hualien County Government to initiate necessary evacuation measures to ensure the safety of downstream residents.
Director Huang emphasized that past monitoring mostly relied on aerial photography and rudimentary instruments. Now, the real-time water level data will not only improve risk assessment capabilities, but also provide a more scientific basis for disaster prevention decisions. He expressed special thanks to the National Airborne Service Corps for its professional support, which allowed the mission to be completed successfully.
FANCA Hualien once again calls on the public not to enter the Matai’an River bed and surrounding waterways. Please continue to pay attention to alert information released by government agencies to jointly safeguard life and property.