• Journal of the Korean Association of Geographic Information Studies
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• v.18 no.3
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• pp.35-51
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• 2015

The purpose of this study is to improve the previous groundwater contamination vulnerability assessment method, apply it to the study area, and select priority areas for groundwater management based on the quantitative analysis of groundwater contamination vulnerability. For this purpose, first, the previous 'potential contamination' based on groundwater contamination vulnerability assessment method was upgraded to the methodology considering 'adaptation capacity' which reduced contamination. Second, the weight of groundwater contamination vulnerability assessment factors was calculated based on the analytical hierarchy process(AHP) and the result of survey targeting groundwater experts. Third, Gyeonggi-do was selected as the study area and the improved methodology and weight were implemented with GIS and actual groundwater contamination vulnerability assessment was carried out. Fourth, the priority area for groundwater contamination management was selected based on the quantitative groundwater contamination vulnerability assessment diagram. The improved detailed groundwater contamination vulnerability assessment factors in this study were a total of 15 factors, and 15 factors were analyzed as new and improved weight with higher 'adaptation capacity' than the assessment factor corresponding to the previous 'potential contamination' in the weight calculation result using AHP. Also, the result of groundwater contamination vulnerability assessment in Gyeonggi Province using GIS showed that Goyang and Gwangmyeong which were adjacent to Seoul had a high groundwater contamination vulnerability and Pocheon and Yangpyeong County had a relatively low groundwater contamination vulnerability. In this study, the previous groundwater contamination vulnerability assessment was improved and applied to study areas actually. The result of this study can be utilized both directly and indirectly for the groundwater management master plan at national and local government level in the future.

• 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.

• Journal of Soil and Groundwater Environment
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• v.13 no.6
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• pp.1-16
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• 2008

There are generally two types of groundwater vulnerability assessments. Intrinsic vulnerability is based on the assessment of natural climatic, geological and hydrogeological attributes and specific vulnerability relates to a specific contaminant, contaminant class, or human activity. Several methods to assess groundwater vulnerability, which are based on hydrogeologic setting and socio-economical environment, have been developed in USA and Europe. A Modified-DRASTIC model including a lineament factor has been developed in South Korea, but it still has some limitations. To develop a solid and applicable method in this country, many data of quality, hydraulic features, GIS data, and pollution source, produced from a Basic Survey based on Article 5 of the Groundwater Act and other research projects, need to be collected, analyzed and verified introducing the previous methods.

• Journal of the Korean Society of Groundwater Environment
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• v.4 no.4
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• pp.223-230
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• 1997

DRASTIC system developed by U.S.EPA, is widely used for assessing regional groundwater pollution susceptibility by using hydrogeological factors such as depth to water, net recharge, aquifer media, soil media, topography, vadose zone media, hydraulic conductivity. The system can be applied to site selection of well or waste disposal and landuse for groundwater protection. In this study, hydrogeological spatial database of Younggwang area about topography, drainage, well, geology, soil and landuse was constructed using GIS (Geographic Information System) and regional groundwater pollution susceptibility is analyzed using the spatial database and GIS overlay technique.

• 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.

• Journal of Soil and Groundwater Environment
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• v.13 no.1
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• pp.77-91
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• 2008

In this study, we developed a technique of applying DRASTIC, which is the most widely used tool for estimation of groundwater vulnerability to the aqueous phase contaminant infiltrated from the surface, and a groundwater flow model jointly to assess groundwater contamination potential. The developed technique is then applied to Buyeo-eup area in Buyeo-gun, Chungcheongnam-do, Korea. The input thematic data of a depth to water required in DRASTIC model is known to be the most sensitive to the output while only a few observations at a few time schedules are generally available. To overcome this practical shortcoming, both steady-state and transient groundwater level distributions are simulated using a finite difference numerical model, MODFLOW. In the application for the assessment of groundwater vulnerability, it is found that the vulnerability results from the numerical simulation of a groundwater level is much more practical compared to cokriging methods. Those advantages are, first, the results from the simulation enable a practitioner to see the temporally comprehensive vulnerabilities. The second merit of the technique is that the method considers wide variety of engaging data such as field-observed hydrogeologic parameters as well as geographic relief. The depth to water generated through geostatistical methods in the conventional method is unable to incorporate temporally variable data, that is, the seasonal variation of a recharge rate. As a result, we found that the vulnerability out of both the geostatistical method and the steady-state groundwater flow simulation are in similar patterns. By applying the transient simulation results to DRASTIC model, we also found that the vulnerability shows sharp seasonal variation due to the change of groundwater recharge. The change of the vulnerability is found to be most peculiar during summer with the highest recharge rate and winter with the lowest. Our research indicates that numerical modeling can be a useful tool for temporal as well as spatial interpolation of the depth to water when the number of the observed data is inadequate for the vulnerability assessments through the conventional techniques.

• Journal of the Korean Association of Geographic Information Studies
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• v.6 no.2
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• pp.101-112
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• 2003

This paper designs and implements the management system that can calibrate the contamination vulnerability of the ground water, using an object oriented data model. Geographic-objects are specified by features extracted from an applicable geographic domain, and geographic-fields are defined by chemical factors extracted from each driven water. To show the topological relationships among the geographic-objects and the geographic-fields, this paper attach the weight and the ratio of the drastic model to chemical factors represented on the land use digital map and the ground water digital map. The geographic feature class, administrative boundary class, land use class and driven water class consist of a class composition hierarchy for evaluating the convenient contamination vulnerability calibration with spatial relationships among the well objects. Therefore, this management system for evaluating the contamination vulnerability can also contribute to the application of other natural environments.

• 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.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.282-282
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• 2020

본 연구는 여수시 농어촌지역에 대하여 지하수 함양특성, 개발가능량 산정 및 오염부하량 등의 조사를 통해서 체계적인 지하수자원의 보전관리(안)을 수립하기 위해 수행되었다. 연구지역은 여수시 화양면, 소라면 2개 면을 포함하는 농어촌 용수구역(여소지구)으로, 여소지구의 총면적은 130.68 ㎢이며, 이 중 임야면적은 81.57 ㎢, 경지면적은 32.98 ㎢ 이고, 경지면적은 논 15.37 ㎢, 밭 17.42 ㎢, 시설재배 0.19 ㎢로 구성되어 있다. 여소지구의 30년 강수평균은 1,454.08 mm/년이며, 지하수 함양량은 국가지하수관리 기본계획(국토교통부, 2019) 및 전라남도 지하수관리계획(전라남도, 2009) 보고서를 참고하여 평균값인 11.28%로 산정한 결과, 21,279 천㎥/년으로 분석되었다. 또한, 지하수연보(국토교통부, 2018)의 세부용도별 이용량을 활용하여 지하수 이용량을 산정한 결과, 2,638.35 천㎥/년이었으며, 강수량, 함양률 및 면적 값을 고려하여 지하수 개발가능량을 산정한 결과, 16,387.57 천㎥/년, 개발가능량 대비 이용량은 16.11%로 확인되었다. 여소지구의 질산성질소 항목은 총 181개소(경지면적 0.2 ㎢당 1점)에 대해 분석한 결과, 전체 평균값은 6.67 mg/L이었으며, 농업용수 수질기준(20 mg/L)을 초과한 관정은 8개소(6%)로 확인되었다. DRASTIC을 이용한 오염취약성 지수는 평균값이 119.57점으로 나타나 오염취약성이 낮은 것으로 분석되었다. 신고·허가된 축사 시설을 기준으로 점오염원 조사결과, 단위면적당 시설수(오염원밀도)는 3.12 개소/㎢로 조사되었으며, 인구, 가축 및 토지이용 등 인자별을 고려하여 오염부하량을 산출한 결과, 단위면적당 오염부하량은 75.30 kg/day/㎢로 확인되었다. 행정구역별로 7가지 지표를 반영하여 관심, 주의, 경계 및 심각 4단계로 기준을 설정하여 지하수관리 필요지역을 선정하였다. 수량 측면은 개발가능량 대비 이용량, 단위면적당 이용량 및 관정밀 3가지 지표를 적용하였고, 수질 측면은 질산성질소 평균, 오염취약성 지수, 오염원밀도 및 단위면적당 오염부하량 4가지 지표를 적용하여 선정하였다. 지하수관리 필요지역을 분석한 결과, 전체 18개 리 중에서 14개 리에서 수량관리 12개리에서 수질관리 필요지역이 나타났다. 수량관리 필요지역은 지하수 취수량 조정 및 관리 확충 등의 대책방안이 마련되어야 하며, 수질관리 필요지역은 주변 오염원관리 및 수질검사 강화 등의 대책방안이 필요할 것으로 판단된다.

• 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.