本研究之研究目的為藉由地理資訊系統(GIS)解析數值地形模型(DEM)之 資料，並萃取流域內之地貌參數計算各集水區內其溪流點的集水區險峻值 (Melton Ratio)，並將各個集水區內其溪流點依據其 Melton Ratio 值的變化趨 勢進行六種分類。在本研究中則以南投的陳有蘭溪和宜蘭的蘭陽溪為主要研 究流域。其中依據 MR 值趨勢所進行的分類中，兩流域最多的分類皆為第三 類。除了 Melton Ratio 因子以外，本研究同時進行了各子集水區形狀係數的 計算以及比較，並以形狀係數和 Melton Ratio 趨勢分類和土砂災害種類、集 水面積進行比對。其中可以推得形狀係數越大，土砂災害以洪水、高含砂水 流較為常見；形狀係數越小，則以土石流較為常見。;The study mainly uses Geographic Information System (GIS) to analyze Digital Elevation Model (DEM), and to extract the geomorphic parameters in different mountainous watersheds in Taiwan. The Melton Ratio, representing the watershed steepness, along the stream points in each catchment area was examined, and the patterns are classified into six categories according to their spatial trends. The third category, MR decaying downstream, is dominant among other categories in both Chenyoulan River at Nantou county and Lanyang River at Yilan county. In addition to the Melton Ratio, this study also explores the shape coefficients of each sub-catchment area, and uses the shape coefficient and Melton Ratio trend to distinguish the types of slopeland disasters. The larger the shape coefficient, slopeland disasters are more prone to floods and debris floods. On the other hand, the smaller the shape coefficient, the more common slopeland disasters are debris flows or landslides.
