Mirco-Geomorphology Differences Between Channelized Debris Flow with Hillslope Debris Flow

Abstract

The micro geomorphology characteristics of 47 hillslope debris flow (HDF) and 16 channelized debris flow (CDF) events were studied to explore the difference between HDF and CDF. In Taiwan, debris flow torrents are classified into CDF and HDF two types. CDF watershed consists of tributaries and gullies, in which one or multi tributaries might occur the debris flow then inducing the CDF. HDF is located upstream of the watershed and caused by a landslide on the slope and transforming into HDF. The result shows that the factors of CDF are larger than those of HDF including the watershed area, initiation region, length of the transport segment, and elevation differences of the transport segment. The gradient of the riverbank slope is similar between CDF and HDF. However, the channel gradient of the transport segment of HDF is higher than that of CDF. The gradient ratio between the channel gradient and the average gradient of the riverbank slope on the transport segment of CDF is smaller than the gradient ratio of HDF, revealing that CDF valley erosion is higher than HDF valley. This study attempts to establish the criteria for the interpretation of CDF and HDF and explores the differences between the two in the topographic characteristics.