本研究進行莫拉克颱風高屏溪流域125處土石流現地調查及判釋分析,依土石流發生區位、產狀與特性等,將前述土石流分類成坡面型土石流與溪流型土石流。為提供坡面型土石流評估依據,本研究訂定共12項定性與量化判釋準則,且選取集水區面積與河道長度兩項因子,建立判別準則。本文進一步以中部地區桃芝颱風發生之坡面型土石流事件以檢核該準則,結果顯示該判別式可有效區分坡面型土石流與溪流型土石流,因此具良好適用性。其次,本研究綜合歸納坡面型土石流之特性中,發現坡面型土石流在地形沖蝕行為,扮演由溝壑沖蝕至野溪間之過渡形態。本文同時界定出溝壑與野溪之界限,訂定地形發展指標(TDI)。
125 debris flow events in Kao-ping River in Typhoon Morakot were studied on the location, occurrence and topographic characteristics. The hillslope debris flow (HDF) was distinguished from 125 debris flows according to the special characteristic on the occurrence and topographic characteristics. 12 criteria were proposed to identify the hillslope debris flow from the stream debris flows, the description and the quantification on the occurrence of hillslope type debris flow are also presented in the thesis. Two variables of the discrimination formula were derived from catchment area and catchment length to fulfill the distinction the hillslope type and stream type of debris flow. Debris flow events initiated in the Typhoon Toraji in central Taiwan were examined by the foregoing discrimination formula, and shown the effectiveness. Moreover, the study also proposal a theory that the hillslope debris flow is a transition stage from the gully to the torrent in geomorphology erosion process. Last, the study defines the border on the gully and the torrent and the index of topographic development indicator (TDI) was achieved.