本研究於苗栗三義火炎山一號坑溝內進行土石流事件之現地監 測與分析，監測儀器包含雨量計、地聲感應器、縮時攝影機(Time Lapse Camera,TLC)、攝影機(CCD)及無人機(UAV)等。本研究依土石流歷程 發展，將一號坑溝的右支流劃分成六個區塊，並在各區段設置縮時攝 影機(Time Lapse Camera,TLC)進行監測。三維地聲儀收集土石流所造 成的地表震動訊號，再利用快速傅立葉轉換(Fast Fourier Transform, FFT)找出土石流之特徵頻率。2018-2019 年火炎山土石流事件之特徵 頻率介於15 至55 赫茲，再利用希爾伯特-黃轉換(Hilbert-Huang Transform,HHT)分析土石流時序-頻率-能量之關係。土石流側積堤及 河道上堆積之舌狀堆積顯示較大顆粒的主軸排列有平行河道的趨勢。;The debris flow events in Houyenshan Gullies of Sanyi, Miaoli County were explored in this study by deploying the on-site monitoring system, which includes the rain gauge, geophones, Time Lapse Camers (TLC) , CCD and the unmanned aerial vehicle(UAV). The right tributary of the first gully is delineated into six segments based on the transport process of debris flows, and the movements were captured by the Time Lapse Cameras (TLC) installed in each segment. The ground vibration signals recorded by the three-dimensional geophone were analyzed by the Fast Fourier Transform (FFT). The peak frequency of debris flows at Houyenshan is between 15 and 55 Hz. The frequency modulation process then was analyzed by employing the Hilbert-Huang Transform (HHT). The topography and terrain changes of the debris flow are surveyed by employing both the total station and UAV. The main axis of larger boulders (above the median size) in both the lobes and lateral levees tend to be parallel the flow direction channel.
