• Journal of The Geomorphological Association of Korea
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• v.23 no.2
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• pp.109-125
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• 2016

This study aims to identify the landslide susceptible zones of Boeun area and provide reliable landslide susceptibility maps by applying different modeling methods. Aerial photographs and field survey on the Boeun area identified landslide inventory map that consists of 388 landslide locations. A total ofseven landslide causative factors (elevation, slope angle, slope aspect, geology, soil, forest and land-use) were extracted from the database and then converted into raster. Landslide causative factors were provided to investigate about the spatial relationship between each factor and landslide occurrence by using fuzzy set and logistic regression model. Fuzzy membership value and logistic regression coefficient were employed to determine each factor's rating for landslide susceptibility mapping. Then, the landslide susceptibility maps were compared and validated by cross validation technique. In the cross validation process, 50% of observed landslides were selected randomly by Excel and two success rate curves (SRC) were generated for each landslide susceptibility map. The result demonstrates the 84.34% and 83.29% accuracy ratio for logistic regression model and fuzzy set model respectively. It means that both models were very reliable and reasonable methods for landslide susceptibility analysis.

• 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.

• Journal of The Geomorphological Association of Korea
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• v.24 no.3
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• pp.61-81
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• 2017

Traditional approaches to surface moisture problems in the context of aeolian research have focused on the initiation of sand movement, developing various models for predicting threshold velocity on a wet surface. They have been unsatisfactory, however, in explaining field observations because they have not incorporated spatiotemporal variability of surface moisture, the interactions between transported sand grains and surface, and the role of aeolian transport in controlling surface moisture. As Nield (2011) showed, a simplified numerical model can be used to investigate this issue. This research aims to explore the feedback structures between aeolian transport and surface moisture using a modified sand slab model. Key modifications are the introduction of simultaneous updating scheme for all the slabs and moisture-assigning procedures with and without aeolian transport. The major findings are as follows. Moist surface conditions suppress sand slab movement, leading to the development of smaller-scale topography. Available sands for aeolian transport are determined by the vertical patterns of moisture content with its variations from groundwater to the surface. Sand patches on a wet surface act as a localized source area. Sand movement drives immediate changes in surface moisture rather than time-lag reponses, mostly when moist conditions are dominant.

• Journal of The Geomorphological Association of Korea
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• v.23 no.2
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• pp.15-27
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• 2016

Since restoration of damaged geomorphological sites is almost impossible, it is necessary, to select and conserve geomorphological heritages in a preemptive action. Algific (=producing cold) sites are one of the natural resources which have not been protected well due to the lack of understanding of their value, despite their conservation importance. This research aimed to help people to recognize such geosites' actual value and make them understand the necessity of protecting these sites. Algific areas are valuable by the simple fact that it is a mysterious phenomenon in which the ice forming may happen even in the mid-summer and the environment is always cool. Algific sites deserve geomorphological research in the sense that topographic condition called talus causes this phenomenon. They are also valuable in plant geographic sense because northern rare plants survive isolatedly due to low-temperature environment of these sites. Their cultural-historical value is also high by the fact that they have been connected closely with local residents' lives shown by its nicknames, "natural refrigerator" or "natural air conditioner".

• Journal of The Geomorphological Association of Korea
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• v.24 no.4
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• pp.91-101
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• 2017

The Okjukdong dune in Daecheong Island attracts national attention because of its unique landscape that is not covered by vegetation. However, there has been little knowledge on the timing of the dune formation, associated wind regime, and conservational strategies. In this study, we used OSL dating and grain size analyses to reveal the history of the dune development. In addition, we analyzed the wind regime in the dunefield which is surrounded by artificial coastal forest. The fine sand at Okjukdong underlain by a colluvial gravel layer indicates that the dune has been developed since at least 5 ka. Aeolian sands were found to be deposited around 700 years ago. The dunefield appears to have been severely eroded 30~60 years ago. The dune landscape has been destroyed after constructing a windbreak forest around the dunefield. The sand seems to be moving south and north with the season.

• Journal of The Geomorphological Association of Korea
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• v.24 no.4
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• pp.103-115
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• 2017

This paper shows the types of deteriorated hiking trails and degrading factors at three Great Walks such as Tongariro Alpine Crossing, Routeburn Track and Kepler Track in New Zealand. The deteriorated trails could be classified into gullying, widening, narrowing, branching and sidewall erosion. Department of Conservation carefully manages overland flows on trails for preventing surface erosion, thus the Great Walks show only a minor problem of gully on trails which is usually active in a mountainous area. Widening and branching of trails caused by tread erosion are not also developed due to the restriction of visitors as well as the management of rainwash. However, despite the detailed maintenance and prevention of an overuse of trails, some trails traversing steep slopes in a alpine zone under a periglacial environment are severely degraded along their sidewalls. It suggests that a unvegetated sidewall of trails has to be strictly managed in an early stage of occurrence and a slope-traversing section should be selected with more consideration when establishing a route of hiking trails.

• Journal of The Geomorphological Association of Korea
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• v.24 no.2
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• pp.51-64
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• 2017

The paleo-environments including changes in vegetation, climate, and sea level since the middle Holocene(6,400(?)-1,800(?) yr BP) were reconstructed with the special reference to pollen analysis from two trench samples at Yulha-dong, Kimhae-si, southern Korea. The environmental characteristics by the pollen zonation wassummarized asfollows: Pollenzone I(6,400(?)~3,940(?) yr BP)showed the dominance of Quercus species with broad-leaved trees, it was warm condition. Pollenzone II(3,940(?)~2,300(?) yr BP) was characterized to the yellow soil indicating terrestrial environment. Moreover, it showed Alnus-NAP period related to the extension of agriculture and deforestation by the rapid decrease of Quercus and increase of Gramineae. Pollenzone III(2,300(?)~1,800(?) yr BP) showed human impact from the increase of NAP and Pinus. Plenty of Quercus with deciduous broad-leaved trees also suggested warmer condition than before.

• Journal of The Geomorphological Association of Korea
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• v.23 no.3
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• pp.13-25
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• 2016

The purpose of this study is to investigate the location characteristics in which 'large Jar coffin' (hereinafter referred to as 'Jar coffin') distributed in the Yeongsan river basin area in Jeonnam province by means of topographic analysis. 75 Jar coffins (74.3%) in 19 relics (90.5% of total) were found in hill and 26 Jar coffins (25.7%) of two consumption relics (9.5%) were found in floodplain. Among them, 34 (45.3% of total) and 41 (54.7% of total) Jar coffins were found in the Crest surface and Sideslope of hills, respectively. In particular, 26 (34.7%) Jar coffins are mostly located in the Crest flat. This result implies that people at that might be consider the river inundation, and mostly choose hill rather than floodplain when building the Jar coffin. therefore amongtherefore among micro-landform units of the hill, it seems that the 'Crest flat' was the preferred place for the building the Jar coffin at that time.

• Journal of The Geomorphological Association of Korea
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• v.19 no.2
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• pp.187-195
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• 2012

Daisetsuzan National Park in Hokkaido, Japan, has an extensive alpine region due to the topographic feature of lava plateau, and exhibits the surface geology largely composed of pyroclastic materials. In addition, the peak season of mountain climbing in the park coincides with a snow-melting period, resulting in severe soil erosion along hiking trails generated by human trampling, snow-melting water and pipkrake. Trail section has been particularly enlarged because the snow-melting water scours a trail surface and the pipkrake erodes sidewalls of a trapezoid-shaped trail. The scoured tread also forces hikers to walk out of a trail, and then frequently brings about path divergence as well as path widening. The soil particles, which are produced by erosional processes in a slope reach, flow downward, and cause the secondary trail degradation by covering a tread in a flat reach and nearby grassland.

• Journal of The Geomorphological Association of Korea
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• v.23 no.1
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• pp.47-60
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• 2016

In this study, datum points measurement have been collected and then weather data have been analyzed to figure out erosion and deposition environmental change around Halmi-island, Baramarae. First of all, it was difficult to analyze geomorphological change which is caused by climate change because of quite short term of collection period of data. However, differences in spatial distribution of erosion and deposition have locally been shown. In all season, the wind is blowing in north and north-west direction mostly except in summer which is shifted to south direction. However, since its ratio which are above 5m/s is much lower than the north and north-west wind, its effect on geomorphological process is very tiny. In order to look at a tendency of erosion and deposition environmental change around Baramarae Halmi-island, the periphery of Halmi-island was classified to east and west part, then accumulated erosion and deposition values have been calculated. As a result, generally, the datum points are located in the west part which are mostly depositional sites. On the other hand, the datum points are located in east part showed the dominant erosion patterns.