곡저추출 방법의 비교분석을 통한 산지유역 곡저추출 방법 제안

Abstract

The mountain catchments where deep valley networks develop continuously are the main places for agriculture and forestry activities. Understanding the geomorphological characteristics of the valley is primarily needed for managing the natural landscapes in mountain catchments. With respect to the characterization of valley geomorphology, delineating the valley bottom is the most fundamental step. However, previous studies on valley bottom extraction focused on wide and unconfined valleys; they excluded colluvial valleys in headwater catchments. Here, we evaluated the suitability of two methods widely used to extract valley bottoms, specifically applying to a mountainous catchment where colluvial valleys dominate. Our results demonstrated that the Valley Confinement Algorithm (VCA) that delineates valley bottoms by adjusting flood height was more suitable than the Geomorphons-based method that extracts valley bottoms according to the topographic patterns corresponding to valley bottom morphologies. It is mainly because the Geomoprhons-based method should be applied differently to each valley type. In contrast, the VCA applies consistently to the whole area of the study catchment. The extracted valley bottom width is proportional to the power of the drainage area in this study area. In particular, the valley bottom width of fluvial valley increase more rapidly than that of colluvial valley.