현재의 지형은 지형윤회 현상(수만년 단위) AbstractThis study is aiming at reviewing how to set the reference point based on the topography and location characteristics to develop a means of debris hazard management of urban mountain. This study used in each of three models for predicting the moveable debris discharge and reaching distance. According to the results reviewed on Seoul Mt. Umyeon district, it was delineated and divided as the total of 46 watershed. (b), (d) and (e) of the adopted models are specified as reasonable on calculating debris quantity and reaching distance. But predicted quantity and distance are specified as over-estimated when the adopted result values is compared with on-site. Although the models gets excessive estimates, they can demarcate the area of production and deposition. Therefore these models are considered to be adoptable in making the base map for field referencing and managing on a given urban mountain.
Close on the heels of the East Coast Forest Fires (ECFF) in April 2000, Samcheok in the region witnessed landslides in October 2019. Therefore, it is imperative to understand the association between forest fire and slope stability. Accordingly, survey plots were set up around the site of the landslide to investigate micro-topography, forest structure, and growth environment. The results revealed that B plots scored high on appearance and the density of trees, while A plots had high values on the H/D ratio. Further, it is important to control tree density in the restored forests because the H/D ratio, which induces slope stability, exceeds suitable values at both A and B plots, resulting in intense competition among the trees growing in the affected sites. The findings are useful for proposing a mountain management project to prevent sediment-related disasters. Moreover, they would aid in evaluating the root cohesion of trees contributing to slope stability on the east coast region of Gangwon-do, which is prone to disasters such as large-scale forest fires, heavy rains, and landslides.
In this study, vegetation succession and the rate of consequent topsoil development were investigated in shallow landslide scars of sedimentary rock slopes covered by volcanic ashes and pumice in Kagoshima prefecture, Japan. Seven shallow landslide scars of different ages were selected as study areas. In the initial period after the occurrence of a shallow landslide, deciduous broad-leaved trees such as Mallotus japonicus or Callicarpa mollis were occupied in the areas. Approximately 30 years after the landslide, evergreen broad-leaved trees such as Cinnamomum japonicum invaded in the areas, already existed present deciduous broad-leaved trees. After 50 years, the summit of the canopy comprised evergreen broad-leaved trees such as Castanopsis cuspidata var. sieboldii and Machilus thunbergii. Moreover, the diversity of vegetation invading the site reached the maximum after 15 years, followed by a decrease and stability in the number of trees. The total basal areas under vegetation increased with time. It was concluded that the vegetation community reaches the climax stage approximately 50 years after the occurrence of a shallow landslide in the study areas, in terms of the Fisher-Williams index of diversity () and the prevalence of evergreen broad-leaved trees. Moreover, according to the results of topsoil measurement in the study areas, the topsoil was formed at the rate of 0.31 cm/year. The development of topsoil usually functions to improve the multi-faceted functions of a forest. However, when the increased depth of topsoil exceeds the stability threshold, the conditions for a shallow landslide occurrence are satisfied. Therefore, we indicated to control the depth of topsoil and strengthen its resistance by forest management in order to restrain the occurrence of shallow landslides.
Applying stereovision-typed aerial photo for the landslide analysis of mountain is one of the popular method in the parts of geomorphology and disaster analysis. This study explores the landslide effects by overlapping digital aerial photo, digital terrain map, and DEM on the soft photogrammetry. The standardization for observing the landslide effects is developed, and systematization is explored by interpreting the procedure and know-how, and finally drawing up of a interpretation map. In this way, total of 23 types of interpretation indicator were selected, and able to develop the procedure for overlapping data selected for applying each indicator. Finally, the whole process was applied to the case of Mt. Umyeon in the city of Seoul, and could developed 13 interpretation legends.
As casualties are increased due to a landslide recently, it is emphasized that the division of a dangerous area from sediment disaster, specially in an urban area, is getting important. The aim of this study is to redefine how to delineate debris flow-prone area based on the hydrological micro-topography analysis techniques and to enhance the cognitive of residents on that risk in an urban mountainous area. As the results, movable sediment (V ec ) is excessively larger than the erosional sediment (V e ), the range of runout distance is in order of using spread angle(L 3 ), set lowest part of the debris flow-prone area(L h ), using stream length(. Therefore, the value of (L 1 ), (L 2 ) are proper in urban area, it was projected to be more proper that the value of (L 3 ) and (L h ) applicate in bigger watershed and lower development part. The method of hydrological microtopography analysis is likely to contribute to strengthening the activity of social disaster prevention by enabling the self-diagnostic determination of inhabitants on dwelling areas.
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