• Journal of the Korean Society of Safety
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• v.26 no.2
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• pp.83-88
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• 2011

Annually, many parts of the Korea have been damaged from the localized heavy rain and/or typhoons which peak between June and September, which result in extensive financial and human loss. Especially, because the most area of Gangwon province is composed of the steep slope mountains, the damages by the debris flow or land-sliding are more frequent and the frequency has been increased. To analyze the characteristics and causes of these debris flow disasters, lots of study are recently being conducted through database of weather, hydrologic, soil etc using a GIS or remote sensing. In this study, we applied GIS method to analyze the risk of the debris flow area. With the statistical analysis and infinite slope stability model(SINMAP), the debris flow risk level of the mountain slope was generated. As a result, the GIS statistical analysis showed high correlation that former model of SINMAP in determining the debris flow risk area.

• Journal of The Geomorphological Association of Korea
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• v.28 no.1
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• pp.1-12
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• 2021

This study tried to reveal relative surface denudation resistance and ranking by geologic types in the Southern Korean Peninsula using an 1:250,000 digital geologic map and ASTER GDEM. Among rock types such as igneous, sedimentary and metamorphic rocks, metamorphic rock showed the greatest resistance to surface denudation. The most resistant rock to surface denudation by geologic periods (e.g., the Precambrian, Paleozoic, Mesozoic and Cenozoic) was found from the Precambrian. Among the major tectonic settings in the Southern Korean Peninsula such as the Gyeonggi massif, Okcheon belt, Yeongnam massif, Gyeongsang basin and Pohang basin, the Okcheon belt indicated the greatest resistance. The most and least resistant rocks from the representative nine rocks in the Southern Korean Peninsula were Paleozoic limestone, and Cretaceous sedimentary rock and Cenozoic sedimentary rock, respectively. This study suggests that Paleozoic limestone, Cretaceous volcanic rock, Paleozoic sedimentary rock and Precambrian gneiss can be regarded as hard rocks with high elevation, steep slope and complicated relief, while soft rocks with low elevation, gentle slope and simple relief are Jurassic granite, Cretaceous sedimentary rock and Cenozoic sedimentary rock.

• Journal of Soil and Groundwater Environment
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• v.28 no.6
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• pp.45-57
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• 2023

To assess land subsidence estimation and preparedness in the Geum River basin, this study applied GIS techniques and identified six key areas. The Geum River basin has experienced an increase in heavy rainfall since late 2010, and four study areas have shown an increase in groundwater levels. Land subsidence primarily occurred from June to September, with higher rainfall years in 2020 and 2023. Approximately 83.6% of land subsidence in Chungcheongbuk-do province occurred in Cheongju-si, mainly attributed to aging sewage pipes. The regions experiencing population growth have likely led to the construction of underground infrastructures and sewer pipes. Thus, it is considered that various factors, including sewage pipe leaks, precipitation, slope gradient, low drainage density, and groundwater level fluctuations, have contributed to land subsidence. Improving land subsidence estimation involves incorporating additional natural factors and human activities.

• Journal of the Korean Society of Hazard Mitigation
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• v.5 no.2 s.17
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• pp.37-44
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• 2005

It reflects well feature of slope that is characteristic of urban river basin of Busan local. In this study, process various hydrological data and basin details data which is collected through basin basis data, hydrological monitoring system(EMS-DEU) and automatic water level equipment(AWS-DEU) for urban flood disaster prevention and use as basin input data of ILLUDAS, SWMM and HEC-HMS in order to examine outflow feature of experiment basin and then use in reservoir design of experiment basin through calibration and verification about HEC-HMS. Inserted design rainfall for 30 years that is design criteria of creek into HEC-HMS and then calculated design floods according to change aspect of the impermeable rate. Capacity of reservoir was determined on the outflow mass curve. Designed detention pond(volume $54,000m^3$) at last outlet upper stream of experiment basin, after designing reservoir. It could be confirmed that the peak flow was reduced resulting from examining outflow aspect. Designing reservoir must decrease outflow of urban areas.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.3
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• pp.427-437
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• 2016

The objective of this study is to develop the regional regression models based on the physiographical and climatological characteristics for estimating flow duration curve (FDC) in ungauged bsisns. To this end, the lower sections with duration from 185 to 355 days of FDCs were constructed from the 16 gauged streamflow data, which were fitted to the two-parameter logarithmic type regression equation. Then, the parameters of the equation were regionalized using the basin characteristics such as basin area, basin slope, drainage density, mean annual precipitation, mean annual streamflow, runoff curve number in order that the proposed regression model can be used for ungauged basin. From the comparison of the estimated by the regional regression model with the observed ones, the model with the combination of basin area, runoff curve number, mean annual precipitation showed the best performance.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.5
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• pp.125-130
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• 2009

Storage function method which considers the non-linearity of the relationship between rainfall and runoff has been frequently used to predict runoff in a basin and a flood pattern. However, it is time-consuming to estimate appropriate parameters of every basin and rainfall event, which requires the empirical parameter equation applicable in Korea. In this study, multiple regression analysis is used to develop empirical equations to estimate parameters of Storage Function method using basin characteristics. The basin area, maximum stream length, and stream slope are considered as the basin characteristics as the result of the regression analysis. Collinearity is removed and trial-and-error method is used to choose the most descriptive parameters to the dependent variables in Han River basin which is divided into 30 subbasins. The developed equations are validated using the rainfall events in MunMak gauging station and named as 'Han River equation'. The equation could provide the useful information about Storage Function method parameter to calculate runoff from a basin and predict river stage.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.605-609
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• 2005

This study is to perform the rainfall-runoff analysis of the basin of Yongdam dam where is loacted in the Geumriver basin. The model used is the SAC-SMA model which was developed by U.S. National Weather Service. The Precipitation data used as the input data of the model are daily ones observed in 2002 and the mean of values recorded in 5 rainfall stations. The evaporation data are used observed in Daejeon meteorological station. The geographical data such as basin slope and stream gradient are elicited from the numerical map analysis. In the verification through the comparison of calculated daily inflow with observed one, parameters used in the model are estimated manually. As the result of verification, total annual calculated inflow is 13,547CMS and agree accurately with the observed one. During the period of one year of 2002, before 100 days and after 250 days, the soil moisture condition in the upper zone was significantly dry and in spite of the rainfall in this period, the runoff was not generated. Through this result, we can observe that the moisture condition in the soil affects strongly the runoff in a basin.

• Journal of the Korean earth science society
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• v.35 no.2
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• pp.131-146
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• 2014

Multi-beam echosounder data and grain size analysis data of surface sediment were acquired and analyzed in order to investigate the shelf-to-slope morphology, geological character, and their geological controlling factors in the southwestern margin of the Ulleung Basin. According to the morphological character, the continental shelf can be divided into two parts: (1) shallow (~100 m) and steep ($0.5^{\circ}$) inner shelf, (2) deep (100-300 m) and gentle ($0.2^{\circ}$) outer shelf. The continental slope is featured with eight distinct topographic depressions of various spatial dimension (~121 $km^2$ in area) and head wall gradient (${\sim}24.3^{\circ}$). They are developed adjacent to each other and presumably formed by submarine landslides which have recurred under the strong influences of earthquakes and eustatic sea-level change. The inner continental shelf and the continental slope are dominated by fine-grained sediment, whereas the outer continental shelf is dominated by coarse-grained sediment. The surface sediment distribution seems dominantly influenced by eustatic sea-level change. The outer continental shelf is mostly covered by coarse relict sediment deposited during lowstand sea-level, while the inner shelf is covered with recent sediment during highstand sea-level. The surface of the continental slope is covered with fine-grained sediments which were supplied by hemipelagic advection process.

• Water for future
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• v.19 no.2
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• pp.139-148
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• 1986

The hydrologic response function in a small basin is expressed by the distribution function of slope length. The characteristics of topographical factors is represented to the concentration time, and the instantaneous unit hydrograph is derived as a hydrologic rsponse function by application of probobility density function. The averaging process of runoff characteristics within watershed was analyzed for a few small watershed where was split up the small basin itself. The method of calculation of the effective rainfall should play important roles in the transformation process from hydrologic response function to runoff hydrograph. In this paper, the Horton's infiltration quation is used as a method of calculation of effective rainfall, a new response function of runoff process is derived. The $\Phi$-index method and the infiltration method are tested by comparing the observed and estimated values.

• Geophysics and Geophysical Exploration
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• v.20 no.2
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• pp.88-95
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• 2017

Chogye basin, which is surrounded by country rock, has a closed-basin form. In such a basin, incident seismic energy can form multiply reflected waves, thus causing energy concentration to occur at this closed-basin area. Microtremor measurement survey was performed at the Chogye basin, which is located in Chogye-myeon and Jeokjungmyeon, Hapcheon-gun, Gyeongsangnam-do, Republic of Korea. Microtremor data were transformed into the frequency domain, and then the horizontal-to-vertical spectral ratios (HVSR) were calculated. Fundamental resonance frequencies were estimated from the HVSR results for every observation point. Using the empirical relationship between site period and thickness for sediment sites in Korea known from the previous study, the distribution of sediment thickness of the Chogye basin was estimated from the fundamental resonance frequencies. Being compared with the mountainous rim with steep slope, the measurement points inside the basin have low values of the fundamental resonance frequency with the minimum of 1.03 Hz, which corresponds to the thickness of sedimentary layer with the maximum depth of about 100 m. A three-dimensional basin model was constructed for bedrock topography of the Chogye basin by an interpolation of basin depths estimated at each measurement site.