• Title/Summary/Keyword: geomorphology analysis

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Three Dimensional Study of the Tidal Flat Geomorphology in the $K\breve{u}$m River Estuary by Multidate Image Analysis

  • Yoo, Hong-Rhyong
    • Korean Journal of Remote Sensing
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    • v.2 no.2
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    • pp.95-105
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    • 1986
  • The geomorophology of the tidal near $K\breve{u}$m river estuary on the west coast of Korea was studied using satellite images. There Landsat image of different tidal moment were geometrically corrected to be overlapped one another. Then topographic contours were extracted for the analysis with concept of 3-D. According to the morphological analysis, the tidal flats around $K\breve{u}$m river estuary area can be classified in three morphologically different groups: one is developped in a belt type along the shore; another is a delta type in the estuary; the other is developped between the shore line and islands. The morphological characteristics of the tidal flats in the study area seems to be mainly influenced by the tidal dynamics which are very storg on the weatern coastal zone of Korea. However the waves and human activities seem also to be important in some part of the area.

Analysis of Spatial Variability of Local Slope by Means of Geographic Information System (지리정보체계를 이용한 국부경사의 공간적 변동성 해석)

  • Kim, Joo-Cheol;Choi, Yong-Joon;Yoon, Yeo-Jin
    • Journal of Environmental Science International
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    • v.21 no.3
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    • pp.297-303
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    • 2012
  • Slope is the geographic factor reflecting the 3-dimensional features of basin and it can be considered as the important geomorphological factor which governs the morphology of basin and the dynamics of water movement. In this study the approach to the 3-dimensional structures of basin is attempted with statistical analysis of local slope which can be defined and measured in easy and objective manner by means of DEM. As a result local slope is confirmed to be a highly variable spatial factor in basin. And distribution map of local slope based on spatial autocorrelation length in this study would be a useful tool in the further research of hydrology and geomorphology.

Estimation of Discharge for the Amazon River Branches with Wavelet Analysis

  • Katabira, Kyoichiro;Ogawa, Susumu;Sakurai, Takako;Takagi, Mikio
    • Proceedings of the KSRS Conference
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    • 2003.11a
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    • pp.346-348
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    • 2003
  • In this study, we attempted to estimate the discharge of the Amazon River branches from JERS-1/SAR images, which are independent of the weather. We visualized some traces of the Amazon River branches, transformed river shapes into a one-dimensional signal, and calculated the characteristics of the river shapes such as the meandering wavelength and the amplitude with Fourier and wavelet analysis. Then, we related the characteristics of the river shapes with the existing discharge data and derived some regression equations. Finally, we estimated the discharge of the Amazon River branches from the SAR images.

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Analysis of the Controlling Factors of an Urban-type Landslide at Hwangryeong Mountain Based on Tree Growth Patterns and Geomorphology (부산 황령산에서의 수목 성장 및 지형 특성을 이용한 도시 산사태의 발생원인 분석)

  • Choi, Jin-Hyuck;Kim, Hyun-Tae;Oh, Jae-Yong;Kim, Young-Seog
    • The Journal of Engineering Geology
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    • v.21 no.4
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    • pp.281-293
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    • 2011
  • We investigated the causes and characteristics of a landslide at Hwangryeong Mountain, Busan, based on aerial photos, annual precipitation data, rock fracture patterns, and geomorphic features using GIS Software, and a statistical analysis of tilted trees. The analyzed slope shows evidence of a previous slope failure event and the possibility of future failures. Although the NW-SE trending slope was relatively stable until 1975, a large-scale slope failure occurred between 1975 and 1985 due to complex factors, including favorably oriented geologic structures, human activity, and heavy rain. This indicates that a detailed study of geologic structures, slope stability, and rainfall characteristics is important for slope cuttings that could be a major factor and cause of urban landsliding events. The statistic analysis of tilted trees shows a slow progressive creeping type of mass wasting with rock falls oblique to the dip of the slope, with the slope having moved towards the west since 1985. A concentration of tree tilting has developed on the northwestern part of the slope, which could reach critical levels in the future. The analysis of deformed trees is a useful tool for understanding landslides and for predicting and preventing future landslide events.

Grain Size Analysis Using Morphological Properties of Grains (입자의 형태적 특성을 활용한 퇴적물 입도분석)

  • Choi, Kwang Hee
    • Journal of The Geomorphological Association of Korea
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    • v.27 no.2
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    • pp.19-28
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    • 2020
  • Grain size analysis is the most basic procedure for identifying the origin, transport and sedimentation processes of sediments, and is widely used in geomorphology and sedimentology. Traditionally, grain size was determined by a sieve-pippette method, but the use of automated analyzers is increasing in recent years. These analyzers have many advantages over traditional techniques, but the measurement results are not always the same. It is still difficult to solve the pretreatment problem such as incomplete diffusion and residual organic matter, and inappropriate results may be obtained. This study compared image-based grain size analysis and sieve analysis to verify its statistical reliability, and conducted experiments to enhance the measurement accuracy using shape parameters. The results showed that the image-based analysis overestimated the grain size of sand dunes by about 7% compared to the sieve analysis, but the two measurements were not statistically different. In addition, by using shape parameters, such as aspect ratio, sphericity, and convexity, improved statistics were obtained compared to the original data. Using the morphological properties of the individual grains is a complementary method to the incomplete pretreatment of the grain size analysis process, and at the same time, it will contribute to improving the accuracy and reliability of the results.

Analysis of Environmental Factors of Geomorphology, Hydrology, Water Quality and Shoreline Soil in Reservoirs of Korea (우리나라 저수지에서 지형, 수문, 수질 및 호안 토양 환경요인의 분석)

  • Cho, HyunSuk;Cho, Kang-Hyun
    • Korean Journal of Ecology and Environment
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    • v.46 no.3
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    • pp.343-359
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    • 2013
  • In order to understand shoreline environment characteristics of Korean reservoirs, the interrelationships between environmental factors of geomorphology, hydrology, water quality and shoreline soil were analyzed, and the reservoir types were classified according to their environmental characteristics in the 35 reservoirs selected by considering the purpose of dam operations and annual water-level fluctuations. Geomorphological and hydrological characteristics of reservoirs were correlated with the altitude and the size scale of reservoirs. The annual range of water level fluctuation showed a wide variation from 1 m to 27 m in the various reservoirs in Korea. The levels of eutrophication of most reservoirs were mesotrophic or eutrophic. From the result of the soil texture analysis, sand contents were high in reservoir shorelines. Range, frequency and duration of water-level fluctuation were distinctive from the primary function of reservoirs. Flood control reservoirs had a wide range with low frequency and waterpower generation reservoirs had a narrow range with high frequency in the water-level fluctuation. According to the result of CART (classification and regression tree) analysis, the water quality of reservoirs was classified by water depth, range of water-level fluctuation and altitude. The result of PCA (principal component analysis) showed that the type of reservoirs was classified by reservoir size, water-level fluctuation, water quality, soil texture and soil organic matter. In conclusion, reservoir size, the water-level fluctuation, water quality and soil characteristics might be major factors in the environment of reservoir shorelines in Korea.

The physical geography in general:yesterday and tomorrow (자연지리학 일반: 회고와 전망)

  • Son, Ill
    • Journal of the Korean Geographical Society
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    • v.31 no.2
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    • pp.138-159
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    • 1996
  • There has been a tendency for Geomorphology and Climatology to be dominant in Physical Geography for 50 years in Korea. Physical Geography is concerned with the study of the totality of natural environment through the integrated approaches. But, an overall direction or a certain paradigm could not be found, because major sub-divisions of Physical Geography have been studied individually and the subjects and the approaches in studying Physical Geography are enormously diverse. A consensus of opinion could not also exist in deciding what kind of the sub-divisions should be included in the physical geography in general and how those should be summarized. Furthermore it would be considered imprudent to survey the studies of Physical Geography besides those of Geomorphology and Climatology due to the small number of researchers. Assuming that the rest of Physical Geographical studies with the exception of Geomorphological and Climatological studies are the Physical Geography in general, the studies of Physical Geogrpahy in general are summarized and several aspects are drown out as follows. First the descliption of all possible factors of natural environments was the pattern of early studies of Physical Geography and the tendency is maintained in the various kinds of research and project reports. Recently Physical Geographers have published several introductory textbooks or research monographs. In those books, however, the integrated approaches to Physical Geography were not suggested and the relationship between man and nature are dealt with in the elementary level. Second, the authentic soil studies of Physical Geographers are insignificant, because the studies of soil in Physical Geography have been mostly considered as the subsidiary means of Geomorphology Summarizing the studies of Soil Gegraphy by physical geographers and other Pedologists, the subjects are classified as soil-forming processes, soil erosions, soil in the tidal flat and reclaimed land, and soil pollution. Physical Geographers have focused upon the soil-forming processes in order to elucidate the geomorphic processes and the past climatic environment. The results of other subjects are trifling. Thirdy Byogeygrayhers and the results of studies are extremely of small number and the studies of Biogeography in Korea lines in the starting point. But, Biogeography could be a more unifying theme for the Physical-human Geography interface, and it would be expected to play an active part in the field of environmental conservation and resource management. Forth, the studies of Hydrogeography (Geographical Hydrology) in Korea have run through the studies of water balance and the morphometric studies such as the drainage network analysis and the relations of various kinds of morphometric elements in river. Recently, the hydrological model have introduced and developed to predict the flow of sediment, discharge, and ground water. The growth of groundwater studies is worthy of close attention. Finally, the studies on environmental problems was no mole than the general description about environmental destruction, resource development, environmental conservation, etc. until 1970s. The ecological perspectives on the relationship between man and nature were suggested in some studies of natural hazard. The new environmentalism having been introduced since 1980s. Human geographers have lead the studies of Environmental Perception. Environmental Ethics, Environmental Sociology, environmental policy. The Physical geographers have stay out of phase with the climate of the time and concentrate upon the publication of introductory textbooks. Recently, several studies on the human interference and modification of natural environments have been made an attempt in the fields of Geomorphology and climatology. Summarizing the studies of Physical Geography for 50 years in Korea, the integrated approaches inherent in Physical Geography disappeared little by little and the majol sub-divisions of Physical Ceography have develop in connection with the nearby earth sciences such as Geology, Meteorology, Pedology, Biology, Hydrology, etc been rediscovered by non-geographers under the guise of environmental science. It is expected that Physical Geography would revive as the dominant subject to cope with environmental problems, rearming with the innate integrated approaches.

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Comparative Analysis of Geomorphological and Folklore Approaches to Weathered Landforms - Focusing on Tafoni, Gnamma, Gamsil and Alter - (풍화지형에 대한 지형학적 분석과 고고민속학적 접근에 관한 비교 연구 - 타포니와 나마, 감실과 알터를 중심으로 -)

  • Park, Kyeong
    • Journal of The Geomorphological Association of Korea
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    • v.24 no.3
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    • pp.119-131
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    • 2017
  • Typical weathering landforms and phenomena including tafoni and gnamma are usually interpreted as man-made alteo (praying water bowl) or dragon-alteo by folklore researchers. Despite some terminological ambiguity, they are certainly natural weathering pits and are introduced in our discipline for fifty years, however, unfortunately most of them are interpreted as petroglyphs used and prepared for ritual ceremony. Several seemingly artificially-made rock holes are also found in many places, but most of them are weathered landforms by salt weathering. Author believes that communication effort to use common language and publish more researches in interdisciplinary journals are very essential to propagate scientific achievements made by geomorphologists to other discipline. Also geomorphologists specialized in weathering processes are encouraged to participate in preservation of stone artifacts and archaeological remains.

Development of Korean Peninsula VS30 Map Based on Proxy Using Linear Regression Analysis (일반선형회귀분석을 이용한 프락시 기반 한반도 VS30지도 개발)

  • Choi, Inhyeok;Yoo, Byeongho;Kwak, Dongyoup
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.42 no.1
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    • pp.35-44
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    • 2022
  • The VS30 map is used as a key variable for site amplification in the ShakeMap, which predicts ground motion at any site. However, no VS30 map considering Korean geology and geomorphology has been developed yet. To develop a proxy-based VS30 map, we used 1,101 VS profiles obtained from a geophysical survey and collected proxy layers of geological and topographical information for the Korean Peninsula. Then, VS30 prediction models were developed using linear regression analysis for each geological age considering the distribution of VS30. As a result, models depending on geomorphology were suggested per each geologic group, including Quaternary, Fill, Ocean, Mesozoic group and Precambrian. Resolution of map is doubled from that of VS30 map by U.S. Geological Survey (USGS). Standard deviation of residual in natural log of proxy-based VS30 map is 0.233, whereas standard deviation of slope-based USGS VS30 map is 0.387. Therefore, the proxy-based VS30 map developed in this study is expected to have less uncertainty and to contribute to predicting more accurately the ground motion amplitude.

Spatial Prediction of Soil Carbon Using Terrain Analysis in a Steep Mountainous Area and the Associated Uncertainties (지형분석을 이용한 산지토양 탄소의 분포 예측과 불확실성)

  • Jeong, Gwanyong
    • Journal of The Geomorphological Association of Korea
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    • v.23 no.3
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    • pp.67-78
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    • 2016
  • Soil carbon(C) is an essential property for characterizing soil quality. Understanding spatial patterns of soil C is particularly limited for mountain areas. This study aims to predict the spatial pattern of soil C using terrain analysis in a steep mountainous area. Specifically, model performances and prediction uncertainties were investigated based on the number of resampling repetitions. Further, important predictors for soil C were also identified. Finally, the spatial distribution of uncertainty was analyzed. A total of 91 soil samples were collected via conditioned latin hypercube sampling and a digital soil C map was developed using support vector regression which is one of the powerful machine learning methods. Results showed that there were no distinct differences of model performances depending on the number of repetitions except for 10-fold cross validation. For soil C, elevation and surface curvature were selected as important predictors by recursive feature elimination. Soil C showed higher values in higher elevation and concave slopes. The spatial pattern of soil C might possibly reflect lateral movement of water and materials along the surface configuration of the study area. The higher values of uncertainty in higher elevation and concave slopes might be related to geomorphological characteristics of the research area and the sampling design. This study is believed to provide a better understanding of the relationship between geomorphology and soil C in the mountainous ecosystem.