Fig. 9.
The panels include observation frames and a scatter plot. Panel a shows a plan view of debris flow movement within a channel, with an arrow indicating flow direction and a dashed line marking the transition between deposited and flowing material. Panel b shows an observation frame of barrier F B 1 with the initial position of the top cable indicated, and basal sensors positioned at 3 point 8 meters from F B 1. Panel c shows an observation frame of horizontal overflow where debris accumulates and passes above the barrier crest. Panel d shows a scatter plot of normalised overflow velocity against normalised overflow landing distance, with values ranging from 0 to 4 for velocity and 0 to 25 for landing distance. Data points from multiple studies including Koo 2017, N g et al. 2020 a, 2023, 2024 a, 2024 b, and 2024 c are plotted, along with calculated curves for slope angles 0 degrees and 31 degrees. The present study at 190-meter flume shows a value of H by h 16 at a velocity near 1, aligning with increasing trends where landing distance rises with increasing overflow velocity.(a) Top plan view during overflow at the first barrier. (b), (c) Front elevation view of the first barrier before debris impact and during overflow, respectively. (d) Normalised overflow landing distance with varying normalised overflow velocity. (Note: (M) and (C) denote measured and computed results; and represent slope inclination and overflow launch angle, respectively)