Source: Dr. Su-Chin Chen (Lifetime Distinguished Professor of Department of Soil and Water Conservation, National Chung Hsing University)
|Prof. Chen’s patent on adjustable check dam for natural disasters reduction in mountain regions.||The experiment term of Prof. Chen’s Lab.|
Earthquakes or extreme rainfalls are likely to cause large-scale landslides and debris flows disasters in mountain regions. When a large amount of sediment intrudes the river, it blocks the upstream flow, and the water accumulates behind the massive deposition, resulting in forming a dammed lake. However, when dam breaching was hazardous and no one could witness it. Therefore, solving the puzzle through the experiment on the onset of disasters would be helpful. The question might be: how large does the breaching flow cause the submergence area? Furthermore, when does the peak discharge occur?
Air photo of the field scale dam breach experimental station in Landao creek
In order to have a better understanding of the breaching process of barrier dams and features of the disaster caused by floods and sediments during the failure, Professor Chen and his research team established the world's first field-scale experiment-site of barrier dam breaching, reconstructing the scene of the disaster in the Landao Creek, NCHU Forest Station, Taiwan.
Multiple UAVs were used to simultaneously record the dam from different dimensions to understand how the dam's material was scoured and deposited. Pressure-type water level gauges were used to record the water level hydrograph to understand the water level variations inside the dam and in the reservoir. Moreover, with the lake's topography, the breaching discharge was inferred. The turbulent flow accompanying the collapse is hazardous. Therefore, in terms of observation and measurement technology, non-contact measurement methods are congruously adopted. In the measurement of flow velocity, Particle Tracking Velocimetry was applied. With the floating characteristics of styrofoam balls supplied above the dam, the trajectory of each styrofoam ball was monitored on the camera screen. The positions of the balls allowed the current velocity to be calculated.
Precise synchronous measurement pre-work for dam breach experiment
“Once we have such a complete set of experimental foundations, we can gradually inform the government and residents about what should be paid attention to in disaster events. This is the fundamental purpose of our experiment,” said Professor Chen. In the past 30 years, he committed himself as a researcher to issues concerning the environment and natural disasters, such as ecosystem services and adjustable check dams. These research achievements won him the “Outstanding Award of MOST in Natural Disasters Reduction in Mountain Regions.” This full-scale experiment is completely open and invites scholars from all over the world to participate. Scholars from Austria, Italy, Switzerland, Japan, and the United States have taken part in the research; meanwhile, domestic research teams from National Taiwan University, National Cheng Kung University, and National Chiao Tung University have jointly set up instruments and shared research results. In the future, it will continue to open to scholars interested in and establish an international data sharing platform, making National Chung Hsing University a pivotal research center for effectively mitigating disasters in the mountain areas.
Notes: Ministry of Science and Technology (MOST) is now renamed National Science and Technology Council (NSCT) from 27th July 2022 onwards.
For more detailed information, please refer to the video: