• Title/Summary/Keyword: geomorphological classification

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Evaluating Geomorphological Classification Systems to Predict the Occurrence of landslides in Mountainous Region (산사태 발생예측을 위한 지형분류기법의 비교평가)

  • Lee, Sooyoun;Jeong, Gwanyong;Park, Soo Jin
    • Journal of the Korean Geographical Society
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    • v.50 no.5
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    • pp.485-503
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    • 2015
  • This study aims at evaluating geomorphological classification systems to predict the occurrence of landslides in mountainous region in Korea. Geomorphological classification systems used in this study are Catena, TPI, and Geomorphons. Study sites are Gapyeong-gun, Hoengseong-gun, Gimcheon-si, Yeoju-si/Yicheon-si in which landslide occurrence data were collected by local governments from 2001-2014. Catena method has objective classification standard to compare among regions objectively and understand the result intuitively. However, its procedure is complicated and hard to be automated for the general public to use it. Both TPI and Geomorphons have simple procedure and GIS-extension, therefore it has high accessibility. However, the results of both systems are highly dependent on the scale, and have low relevance to geomorphological formation process because focusing on shape of terrain. Three systems have low compatibility, therefore unified concept are required for broad use of landform classification. To assess the effectiveness of prediction on landslide by each geomorphological classification system, 50% of geomorphological classes with higher landslide occurrence are selected and the total landslide occurrence in selected classes are calculated and defined as 'predictive ability'. The ratio of terrain categorized by 'predictive ability' to whole region is defined as 'vulnerable area ratio'. An indicator to compare three systems which is predictive ability divided by vulnerable area ratio was developed to make a comprehensive judgment. As a result, Catena ranked the highest in suitability.

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A Geomorphological Classification System to Chatacterize Ecological Processes over the Landscape (생태환경 특성 파악을 위한 지형분류기법의 개발)

  • Park Soo-Jin
    • Journal of the Korean Geographical Society
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    • v.39 no.4
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    • pp.495-513
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    • 2004
  • The shape of land surface work as a cradle for various environmental processes and human activities. As spatially distributed process modelings become increasing important in current research communities, a classification system that delineates land surface into characteristic geomorphological units is a pre-requisite for sustainable land use planning and management. Existing classification systems are either morphometric or generic, which have limitations to characterize continuous ecological processes over the landscape. A new classification system was developed to delineate the land surface into different geomorphological units from Digital Elevation Models(DEMs). This model assumes that there are pedo-geomorphological units in which distinct sets of hydrological, pedological, and consequent ecological processes occur. The classification system first divides the whole landsurface into eight soil-landscape units. Possible energy and material nows over the land surface were interpreted using a continuity equation of mass flow along the hillslope, and subsequently implemented in terrain analysis procedures. The developed models were tested at a 12$\textrm{km}^2$ area in Yangpyeong-gun, Kyeongi-do, Korea. The method proposed effectively delineates land surface into distinct pedo-geomorphological units, which identify the geomorphological characteristics over a large area at a low cost. The delineated landscape units mal provide a basic information for natural resource survey and environmental modeling practices.

Examination into the Applicability of the River Classification System Based on the Geomorphological Criteria (지형 인자를 이용한 하천분류 체계의 적용성 검토)

  • Lee, Chan-Joo;Lee, Du-Han;Kim, Kyu-Ho;Woo, Hyo-Seop
    • Journal of Korea Water Resources Association
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    • v.37 no.1
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    • pp.1-11
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    • 2004
  • The purpose of this study consists in introducing and examining the previous river classification systems applicable to the river improvement technique including geomorphological considerations, and developing a new system using the geomorphological criteria which represent the morphology of rivers. A newly developed system uses the channel reach as a classifying unit which is delineated by upstream and downstream tributaries. It adopts three basic geomorphological criteria for classification: 1) valley-floor width index(VI) reflecting the confinement of the channel in the valley, 2) sinuosity(P) which expresses the channel planform, and 3) bed material($d_{50}$). The system is composed of 24 stream types. Concerning every stream type, valley forms, principal bed forms and fluvial processes with disturbance elements are briefly presented. Finally, the applicability of this system to the Chungmi Stream and the Imjin River data in comparison with that of Rosgen system is examined.

Macrotidal Beach Classifications Considering Beach Profiles and Changes: The Case of Beaches in Taean Region (2017-2018) (지형형태와 변화를 반영한 대조차 해빈 분류: 태안지역 해빈을 사례로(2017-2018))

  • Kim, Chan Woong
    • Journal of The Geomorphological Association of Korea
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    • v.26 no.4
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    • pp.47-65
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    • 2019
  • A case study was conducted in Taean region to seek a more detailed macrotidal beach classification than existing beach classification models (Masselink and Short, 1993). Seepage and ridge & runnel were used for classification. On 20 beaches, 68 transects were surveyed 5 times using VRS-GPS. Cross-section area from the transect profiles, mean grain size from sediment analysis, significant wave height from Swan-wave modeling and beach embaymentization from aerial photograph analysis were used to identify the characteristics of the individual types. The transects were classified into 5 types in Taean region; Type 1: low tidal terrace, Type 2: low tidal terrace & ridge, Type 3: dissipative, Type 4: seasonal ridge, and Type 5: ridge & runnel. Generally, seepage was related to coarse sediment size and ridge & runnel was related to high significant wave height. Each type has different characteristics and there was a tendency between the types. The low tidal terrace type had coarse sediments, because this type is excluded from the littoral cell. In this study, the ridge and runnel type could be applied to the classification because the study area is limited only to the macrotidal environment in Taean region.

Basic Research of the Paleo-Environmental Change and Possibility of Ancient Port Location Through Geomorphological Survey and Sediment Analysisin Hwaseong City (화성 당성 유적 일대의 지형 조사 및 퇴적물 분석을 통한 고환경 변화 및 고대 포구 입지 가능성 기초 연구)

  • Han, Min;Yang, Dong-Yoon;Lim, Jaesoo
    • Journal of The Geomorphological Association of Korea
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    • v.24 no.4
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    • pp.27-41
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    • 2017
  • In this study, geomorphological and geological research has been carried out to estimate the possibility of ancient port location near Hwaseong Dangseong. Geomorphological characteristics around Eunsupo were analyzed through comparison of past and present topographic maps and field survey. Grain size, age dating, and geochemical analysis on surface sediments and borehole sediments were performed. Through the geomorphological characteristics analysis, it was interpreted that Eunsupo area was submerged in seawater especially at high tide in the past, and that ships could approach to the inside of the area through the tidal channel which were developed in the area. It is also assumed that ships were anchored at a low elevation point in the area. The paleo-environmental change in the area was analyzed based on the classification of sedimentary environment using grain size distribution of surface and borehole sediments and geochemical analysis. It was confirmed that the geomorphological interpretation for the possibility of ancient port location coincided well with the paleo-environmental change interpreted through sediment analysis. This study is a basic study for estimating ancient port location, and it is expected that more accurate paleo-environmental changes will be restored through detailed geomorphological survey and additional borehole analysis in the future research.

A Study of Morphometric Characteristics and Mountain Classification in Korean Mountainses (우리나라 산지의 형태적 특성과 산지분류에 관한 연구)

  • Tak, Han Myeong;Park, Sun-Yurp
    • Journal of The Geomorphological Association of Korea
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    • v.24 no.1
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    • pp.63-76
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    • 2017
  • This research was classified mountain areas with high ecological, environmental and resource value among the macro scaled terrain that can be checked at the space scale of less than 1:1,000,000 and analyzed the topographical characteristics. It has been confirmed that the mountains of the Korean peninsula belong to the groups IV, V, VI(classification by Kapos et al.(2000)) as a result of applying the quantitative standards for designation of mountain areas to the global mountain system. The area of mountains calculated using high resolution DEM is equivalent to 48% of the area of the Korean peninsula, and the result is quite different from the general idea of which 70% is the mountain area of the Korean peninsula. The mountain areas show the distribution of geomorphons, that is different from the plains and the hills and also, it shows the differences between the mountains of the groups IV~ VI classified according to the altitude. As a result of analyzing the relations among type pattern, slope, and relief, specific geomorphons are concentrated at $10^{\circ}$ and $20^{\circ}$ and it shows the possibility to classify the mountainous areas into two groups based on the result that the distribution of landform patterns are bimodal in the relation to the amount of relief.

The Characteristics of Geomorphological and Geological Landscapes in Sado, Yeosu City, Korea (여수 사도의 지형 및 지질경관 특성)

  • Kim, Hai-Gyoung;Koh, Yeong-Koo;Oh, Kang-Ho
    • Journal of The Geomorphological Association of Korea
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    • v.20 no.1
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    • pp.35-43
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    • 2013
  • This study is intended to provide resources of on-the-spot experience learning activities for students by investigating characteristics of geomorphological and geological landscapes in Sado(including Jungdo and Jeungdo). There are nine types of geomorphological and geological landscape according to the classification from NIER(National Institute of Environmental Research) or seventeen types of it, according to the categorization from KEI(Korea Environment Institute). Such geomorphological and geological landscapes are useful as a place for on-the-spot learning activities that various types of geographical and geological features suggested in the elementary and middle school textbooks and also as a basic data for ecotourism and geotourism for visitors in Sado. In addition, specific targets to be investigated for geographical and geological heritage suggested by KEI should be determined in terms of conservation value through professional and thorough field investigation.

Landsat 자료를 이용한 금강하류의 충적주 환경변화에 관한 연구

  • 장동호;지광훈;이봉주
    • Korean Journal of Remote Sensing
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    • v.11 no.2
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    • pp.59-73
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    • 1995
  • The study is focused on the analysis of geomorphological environment changes of alluvial bar in lower Kum river using satellite-based multitemporal/multisensor data. Landsat datas for environment changes analysis consists of Landset MSS(2 scenes) and Landset TM(7 scenes) acquired from 1979 to 1994. This study is to develop the analysis techniques for the environment change detection of using ratio, classification, false color composite etc, of Landsat data especially useful to the geomorphological study of tidal flats and river channels. The results of this study can be summarized as follows : 1. The lower Kum River alluvial bar have had rapid geomorphological changes after the construction of the temporary dam to block the river flowing in 1983. The most alluvial bar located in the river has both bankway growth, especially the allurival bar in the Lower Kum River had grown between 1983 to 1990. 2. After construction of the estuarine barrage, no remarkable geomorphological changes have been found in Kum River area but the growth and formation of new underwater bar has continued. The enormous materials was needed for the growth and formations of new underwater barrier oslands and bar would be supplied from the sea bottom and river sediment to diminish of stream velocity after construction of the estuarine barrage.