Characteristics of erosion development and gravelly debris flow hazard zoning in the Houyenshan of Taiwan

This study focused on the erosion development and dynamics of gravelly debris flow at the Houyenshan watershed through geomorphology interpretation, field investigation, and discrete-element method. The study constructed a discrete-element method to simulate the process of gravelly debris flow and determine the scope of influence with regard to deposition. Then, the study integration of the interpretation, field investigation, and simulation results to evaluate erosion and landslide hazard in study area. The results of the integrated study show that of the five major pits, pit No. 3 has the most active erosion development, and a large number of debris flow alluvial fans are accumulated downstream, causing the main road to be interrupted and the main river to change the flow direction. At present, there are still have many tension cracks and local seepage can be seen on the slope surface, causing the gravel slope in the source area to appear unstable. Finally, the results can serve as a reference for disaster prevention, mapping and zoning of the areas susceptible to geological hazards, and associated mitigation project planning.