南投九九峰礫岩惡地集水區凹曲率興地勢特徵一谷系密度關係之探討

Abstract

本文藉由集水區凹曲率與地勢特徵一谷系密度相關性的分析，評估地表逕流侵蝕作用在南投九九峰礫岩惡地地貌發育過程中的相對重要性。分析結果顯示，研究區內的集水區凹曲率偏低，地勢特徵與谷系密度間缺乏高度的相關性，均未能指出研究區內整體谷系的形成是受到地表逕流侵蝕作用的強烈影響。野外調查發現，研究區中段谷系密度較高之地區，其岩層結構有利於滲流侵蝕作用的進行，而此處也有較多的邊坡水平曲折率較大，且雨後礫岩自由面上出現滲流現象，這似表示滲流侵蝕作用是影響研究區內集水區谷系密度差異的主因。

In this paper, watershed concavity and the relationship between topography and drainage density are examined in order to evaluate the relative significance of surface runoff erosion in the conglomeratic badlandlocated in Ninety-nine Peaks, Nantou. The result implies the relative importance of surface runoff erosion to the whole development of ravine network is not evident. Field observation of slope form and processessuggests that seepage erosion may playa critical role in the difference of drainage density among watersheds in study area.