This study analyzed the characteristics of seismic signals induced by small dam breaches, with a focus on dam size and location. The research was conducted in August and in November 2023 on the left bank of the Beigang River in Huisun Experimental Forest in Nantou, Taiwan. Single dams, double dams, and double dams with spur dikes were tested. Accelerometers were installed to collect seismic signals, and the Hilbert–Huang Transform method was used for time-frequency analysis, with comparison of changes in seismic energy and spectra. A positive correlation was observed between water impoundment and breach rate; the faster the water impoundment rate was, the more dramatic
the changes in dam seismic signals and the greater the flood intensity after breach were. Spur dikes effectively reduce
flood erosive energy, offering protection to slopes and river channels behind the spur dikes. These findings can serve as a reference for understanding dam breach mechanisms and the application of spur dikes in hydraulic engineering
design.
Key Words: Landslide dam, spur dike, dam breach, flood, seismic signal, time-frequency analysis.