• Journal of Korea Water Resources Association
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• v.50 no.12
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• pp.815-825
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• 2017

Groundwater management vulnerability was assessed using TOPSIS (Techniques for Order Performance by Similarity to Ideal Solution) for 21 administrative districts in Nakdong river basin. Ten indicators were selected for 21 administrative districts in the Nakdong river basin by collecting natural, human, and social data sets. The selected indicators were standardized using rescale method, and each indicator was weighted by considering the questionnaire of expert group. The results of the weights determination survey showed that the annual average groundwater level index was 0.157 and this is the highest value. The annual average precipitation index was 0.154 and the annual groundwater recharge index was 0.152. The lowest weighted index was 0.043 for population density. Finally, the result of assessment of groundwater management vulnerability showed that Sangju-si was the most vulnerable to groundwater management among 21 administrative districts in Nakdong river basin because the annual average precipitation, annual average groundwater recharge, and annual average groundwater use indicators were highly vulnerable. The second and the third vulnerable regions were Yecheon-gun and Haman-gun respectively. The assessment of groundwater management vulnerability for the five major river basins in Korea can be a essential basis for the establishment of groundwater management policy.

• Journal of the Korean Association of Geographic Information Studies
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• v.9 no.3
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• pp.1-13
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• 2006

The aim of the study is to assess groundwater pollution hazard of Pohang city using the DRASTIC system developed by the US Environmental Protection Agency (USEPA). Hydrogeological spatial databases of the system include information on depth to groundwater, net recharge, aquifer media, soil media, topographic slope, hydraulic conductivity, lineament and potential pollution source. With GIS based on these hydrogeological databases and the DRASTIC system, the regional groundwater vulnerability of the study area was assessed. Then the vulnerability was overlaid with potential pollution source and the regional groundwater pollution hazard was assessed by administrative district. From the results of the study, areas where need the counter plan for groundwater pollution and where should be managed for the groundwater pollution, are identified.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2006.04a
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• pp.316-318
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• 2006

The purpose of this research is to write out vulnerability for western area in Jeju island by using drastic method which is the most frequently utilized among the writing techniques of underground water vulnerability. In case of aquifer, it was divided into two types, gravel layer or not and rated. And soil media was rated two kinds of method. Plan 1 is concerned with only soil class and plan 2 is concerned with soil class and gravels (or rocks), Vadose zone was rated differently according to the ratio of gravel layer. In case of plan 1, the scope of drastic index is from the minimum 77 to the maximum 176, on the other hand, plan 2, the scope of drastic index is from the minimum 79 to the maximum 182. In case of using the water quality data of Nitrate from 1994 to 2004, Pearson correlation coefficient are 0.164(Plan 1) and 0.124(Plan 2) and Spearman correlation coefficient are 0.132(Plan 1) and 0.113.

• Journal of The Korean Society of Agricultural Engineers
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• v.60 no.6
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• pp.33-42
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• 2018

This study evaluated the vulnerability of irrigation water supplied to the crops. The target areas were selected as Dangjin-si, Yesan-gun, and Cheongyang-gun. The survey items of the climate exposure were annual precipitation and rainless days. The sensitivity survey items were cultivation area, groundwater level, evapotranspiration and groundwater consumption. The survey items of the adaptability were Number of groundwater well and Water supply ratio. The survey methods for these items were investigated in a variety of ways, including "National Climate Data Service System", "Korean Statistical Information Service", "National ground water monitoring network in korea annual report" and "Chungcheongnam-do Statistical Yearbook", "HOMWRS". Vulnerability assessment results were rated within the range of 0~100 points. The first grade was rated 0-25, the second grade 26-50, the third grade 51-75, and the fourth grade 76-100. And the lower the score, the lower the vulnerability. As a result, Cheongyang-gun showed a high vulnerability of over 50 points, Dangjin-si showed a low vulnerability rating of 31.20 points and a Yesan-gun of 36.00 points.

• Korean Journal of Soil Science and Fertilizer
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• v.41 no.5
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• pp.330-341
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• 2008

The purpose of this study was to investigate the vulnerability for groundwater contamination at the some cemeteries in Gyeonggi Province. Twenty-eight out of 43 cemeteries in Gyeonggi province were selected for this study. The DRASTIC model was applied to those cemeteries, and the reliance of the model was assessed using the water quality data of the target areas. The DRASTIC model was used for the assessment of the potential for groundwater contamination using hydrogeological factors. Seven factors including depth of water, net recharge, aquifer media, soil media, topography, impact of the vadose zone, hydraulic conductivity of the aquifer were assessed. The DRASTIC index of the study area ranged from 82 to 126 with an average value of $113.99(\pm11.48)$. The DRASTIC index was relatively greater in the northern Gyeonggi province than that in the southern area. The DRASTIC index was similar for the areas with the similar burial rate and burial density. This study demonstrated that burial rate and burial density should be considered along with the 7 basic factors for the evaluation of groundwater vulnerability of the cemeteries.

• Journal of Soil and Groundwater Environment
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• v.27 no.spc
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• pp.92-98
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• 2022

Although various methods have been proposed to assess groundwater vulnerability, most of the models merely consider the mobility of contaminants (i.e., intrinsic vulnerability), and the attenuation capacity of vadose zone is often neglected. This study proposed an evaluation model for the attenuation capacity of vadose zone to supplement the limitations of the existing index method models for assessing groundwater vulnerability. The evaluation equation for quantifying the attenuation capacity was developed from the combined linear regression and weighted scaling methods based on the lab-scale experiments using various vadose zone soils having different physical and biogeochemical properties. The proposed semi-quantifying model is expected to effectively assess the attenuation capacity of vadose zone by identifying the main influencing factors as input parameters together with proper weights derived from the coefficients of the regression results. The subsequent scoring and grading system has great versatility while securing the objectivity by effectively incorporating the experimental results.

• The Journal of Engineering Geology
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• v.10 no.1
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• pp.27-38
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• 2000

We hydrogeologically studied a mountainous area and its vulnerability to groundwater contamination. Groundwater flow and recharge occur mainly through a network of fractures in this areaTransmissivity and storativity obtained from slug, slug interference, and pumping tests range from 3.2$\times$10$^{-3}$ to 2.0$\times$10$^{-2}$$m^2$/min and 1.3$\times$10$^{-7}$ to 9.15$\times$10$^{-4}$, respectively. The groundwater was contaminated bylivestock activities in the upgradient. The groundwater in the downgradient residential area wasthreatened by the upgradient livestock activities.

• Economic and Environmental Geology
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• v.37 no.6 s.169
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• pp.631-645
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• 2004

This study assesses groundwater vulnerability to contaminants in industrial and residential/commercial areas of the city of Changwon, using DRASTIC technique and groundwater data. The DRASTIC technique was originally applied to situations in which the contamination sources are at the ground surface, and the contaminants flow into the groundwater with infiltration of rainfall. Mostly the industrial area has higher DRASTIC indices than the residential/commercial area. However, a part of the residential/commercial area having much groundwater production and great drawdown is more contaminated in groundwater than other industrial and the residential/commercial areas even if it has lowest DRASTIC indices in the study area. It indicates that groundwater contamination in urban areas can be closely related to excessive pumping resulting in a lowering of the water level. The correlation coefficient between minimum DRASTIC indices and the degree of poor water quality for 10 districts is as low as 0.40. On the other hand, the correlation coefficients between minimum DRASTIC indices and the groundwater discharge rate, and between minimum DRASTIC indices and well distribution density per unit area are 0.70 and 0.87, respectively. Thus, to evaluate the potential of groundwater contamination in urban areas, it is necessary to consider other human-made factors such as groundwater withdrawal rate and well distribution density per unit area as well as the existing seven DRASTIC factors.

• The Journal of Engineering Geology
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• v.28 no.4
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• pp.727-740
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• 2018

The media in the undersaturated zone is defined as the uppermost layer of the water table at which the groundwater is unsaturated or saturated discontinuously. The properties of the unsaturated zone can affect the reduction of contaminants that flow from the lower part of soil to the water table. In recent, there have been problems in evaluating groundwater contaminations vulnerability because weighted value for permeability is given, regardless of anisotropy and heterogeneity in the unsaturated media. Geological media have various ranges of permeability. When applying the weighted value, representative of permeability for grain sizes standardized, to construction of contamination vulnerability, it will produce more exaggerated result than the case that considers unsaturated geological properties. In this study, we performed laboratory column tests considering two sets of the unsaturated layers in order to investigate the permeability in anisotropic unsaturated zone with anisotropy. On the basis of the tests, average permeability coefficients were calculated considering the properties of unsaturated media obtained from drill cores in the field. The final contamination vulnerability map constructed shows that the contamination vulnerability map applying the properties of geological media of the unsaturated zone coincides much better with the results measured in the field, compared to the case of contamination vulnerability considering the weighted value in the unsaturated zone.

• Journal of Korean Society of Water and Wastewater
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• v.33 no.5
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• pp.341-351
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• 2019

The purpose of this study was to evaluate vulnerability of drought in small island areas. Vulnerability assessment factors of drought were selected by applying the factor analysis. Ninety Eup/Myon areas in small island were evaluated to vulnerability of drought by entropy method adapting objective weights. Vulnerability consisted of climate exposure, sensitivity, and adaptive capacity. A total of 22 indicators were used to evaluate and analyze vulnerability of drought in small island areas. The results of entropy method showed that winter rainfall, no rainfall days, agricultural population rate, cultivation area rate, water supply rate and groundwater capacity have a significant impact on drought assessment. The overall assessment of vulnerability indicated that Seodo-myeon Ganghwa-gun, Seolcheon-myeon Namhae-gun and Samsan-myeon Ganghwa-gun were the most vulnerable to drought. Especially Ganghwa-gun should be considered policy priority to establish drought measures in the future, because it has a high vulnerability of drought.