• The Journal of Engineering Geology
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• v.13 no.2
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• pp.239-256
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• 2003

The purpose of this study is to investigate the hydrochemical characteristics of emergency-use groundwater in the Daejeon area, and to elucidate the contamination source of $NO_3-N$ and the origin of sulfate in the groundwater. The groundwater shows weak acidic pH, the electrical conductivity ranging from 142 to $903{\;}\mu\textrm{S}/cm$, and the hydrochemical types of $Ca-HCo_3$ and $Ca-Cl(SO_4,{\;}NO_3)$. The Box-Whisker analysis and the Krigging analysis of chemical data of groundwater were made to demonstrate the concentration distribution of hydrochemical composition, and to compare the trend of hydrochemical data. The groundwater in the area of Dong-gu, Jung-gu and Daeduk-gu, where are old town, shows higher electrical conductivity, nitrate content, sulfate and $EpCO_2$ levels than groundwater in new town area of Seo-gu and Yusung-gu. ${\delta}^{15}N$ of groundwater in the area of Seo-gu and Yusung-gu ranges from +7.4 to $+9.6{\textperthousand}$, indicating that major contamination source of $NO_3-N$ is the leakage from municipal sewage pipe lines. ${\delta}^{15}N$ of groundwater in the old town area of Tong-gu, Jung-gu and Daeduk-gu shows the range between +10.2 and $+23.5{\textperthousand}$, meaning that major contamination source is leakage of septic tank. ${\delta}^{34}S$ of groundwater shows the range of $+3~13.4{\;}{\textperthousand}$. Sulfur isotope indicates the possibility of a sulfate reduction and the input of anthrophogenic source.

• The Journal of Engineering Geology
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• v.26 no.4
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• pp.515-529
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• 2016

In this study, geochemical composition, CFCs (Chlorofluorocarbons), ${\delta}^{18}O$, ${\delta}D$, ${\delta}^{13}C$ isotopes and noble gases isotopes (He, Ne) were analyzed to determine their recharge age, source of $CO_2$ gas and noble gases of carbonated hot spring water and carbonated-water samples collected in the Seoqwipo of the Jeju. The pH of the carbonated waters ranges from 6.21 to 6.84, and the high electrical conductivity range ($1,928{\sim}4,720{\mu}S/cm$). Their chemical composition is classified as $Mg(Ca,\;Na)-HCO_3$ and $Na(Ca,\;Mg)-HCO_3$ types. As a result of the calculation of groundwater age using CFCs concentrations as an environmental tracer, the carbonated water and groundwater were estimated to be about 47.5~57.2 years and about 30.3~49.5 years, respectively. The ${\delta}^{13}C$ values of carbonated water range from -1.77 to -7.27‰, and are plotted on thr deep-seated field or the mixing field of the deep-seated and inorganic origin. Noble gases isotopic ($^3He/^4He$, $^4He/^{20}Ne$) ratio shows that helium gas of carbonated hot waters comes from deep-seated magma origin.

• Economic and Environmental Geology
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• v.35 no.5
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• pp.395-406
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• 2002

The sixty natural springs and community wells used as a drinking water in the Daejeon area are mainly located at the parks and the natural green districts. The purpose of this study is to investigate the characteristics of water quality and the contamination of the springs and the wells, and to suggest the management strategy for the springs and wells. For this study, we undertook water quality data from Daejeon City. According to the statistic analysis of water quality data, unacceptable rate as a drinking water was about 28 percent in 1999 and 24.5 percent in 2000, respectively. Major unacceptable factor is coliform, and others are bacteria, yersinia, color, turbidity, Fe and F. The unacceptable rate shows a roughly positive relationship with precipitation, that is, it shows highest rate during a rainy season between June and September. The major contamination source is likely to be the excrement of wild animals around natural springs and wells. Most of springs are vulnerable to the contamination of coliform and bacteria because of short residence time and shallow circulation in subsurface environment. The water samples collected from 31 springs or wells show weak acidic pHs, the electrical conductivity ranging from 63 to 357 $\mu\textrm{S}$/cm, and the hydrochemical types of Na(Ca)-HC0$_3$ and Ca-HC0$_3$. The groundwater samples of low total dissolved solid(TDS) belong to Na(Ca)-HC0$_3$. type, and the groundwater of high total dissolved solid is shifted towards Ca-HC0$_3$ type in the chemical composition. These hydrochemical characteristics indicate that most natural springs is in the early stage of geochemical evolution. The natural springs should be closed during a rainy season, which shows a high contamination rate. We suggest that a protection barrier around the springs should be built to keep wild animals away from the springs.

• The Journal of Engineering Geology
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• v.8 no.3
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• pp.247-259
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• 1998

Groundwater quality of the natural mineral water was investigated in hydrochemical aspects in order to ensure that mineral water meets stringent health standards. There exist 20 mineral water plants in the Daebo granite and 4 mineral water plants in the Bulguksa granite, respectively. Both granite areas show some differences in water chemistry. The pH, EC, hardness, total ionic contents in groundwater of the Daebo granite area are higher relative to those of the Bulguksa granite area. The content of major cations is in the order of Ca>Na>Mg>K, while that of major anions shows the order of $HCO_3>SO_4$>Cl>F. The fact that the $Ca-Na-HCO_3$ type is most predominant among water types may reflect that the dissolution of plagioclase that is most abundant in granitic rocks plays a most important role in groundwater chemistry. Representative correlation coefficients between chemical species are variable depending on geology. In the Daebo granite area, $Ca-HCO_3(0.84),{\;}Mg-HCO_3(0.81),{\;}SiO_2-Cl(0.74),{\;}Na-HCO_3(0.70)$ show relatively good correlationships. In the Bulguksa granite area, fairly good correlationships are found among some components such as K-Mg(0.93), $K-HCO_3(0.92)$, Mg-Cl(0.92), $Cl-HCO_3(0.91)$, and K-F(0.90). According to saturation index, most chemical species are undersaturated with respect to major minerals, except for some silica phases. Groundwater is slightly undersaturated with respect to calcite, whereas it is still greatly undersaturated with respect to dolomite, gypsum and fluorite. Based on the phase equilibrium it is clear that groundwater is mostly in equilibrium with kaolinite and becomes undersaturated with respect to feldspars, evolved from the stability area of gibbsite during water-rock interaction. While the activity of silica increases, there is no remarkable increase in the acivities of alkali ions and pH, which indicates that some amounts of silicic acid dissolved from silica phases as well as feldspars were provided to groundwater. It is concluded that chemical evolution of groundwater in granite aquifers may continue to proceed with increasing pH.

• The Journal of Engineering Geology
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• v.25 no.4
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• pp.533-545
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• 2015

Spatial and seasonal variations in hydrogeochemical characteristics and the factors affecting the deterioration in quality of shallow portable groundwater in an agricultural area are examined. The aquifer consists of (from the surface to depth) agricultural soil, weathered soil, weathered rock, and bedrock. The geochemical signatures of the shallow groundwater are mostly affected by the NO₃⁻ and Cl⁻ contaminants that show a gradual downward increase in concentration from the upper area, due to the irregular distribution of contamination sources. The concentrations of the major cations do not varied with the elapsed time and the NO₃⁻ and Cl⁻ ions, when compared with concentrations in background groundwater, increase gradually with the distance from the upper area. This result suggests that the water quality in shallow groundwater deteriorates due to contaminant sources at the surface. The contaminations of the major contaminants in groundwater show a positive linear relationship with electrical conductivity, indicating the deterioration in water quality is related to the effects of the contaminants. The relationships between contaminant concentrations, as inferred from the ternary plots, show the contaminant concentrations in organic fertilizer are positively related to concentrations of NO₃⁻, Cl⁻, and SO₄²⁻ ions in the shallow portable groundwaters, which means the fertilizer is the main contaminant source. The results also show that the deterioration in shallow groundwater quality is caused mainly by NO₃⁻ and Cl⁻ derived from organic fertilizer with additional SO₄²⁻ contaminant from livestock wastes. Even though the concentrations of the contaminants within the shallow groundwaters and the contaminant sources are largely variable, it is useful to consider the ratio of contaminant concentrations and the relationship between contaminants in groundwater samples and in the contaminant source when analyzing deterioration in water quality.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.698-701
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• 2007

지하수 개발가능량 산정을 위한 함양량의 평가는 수문계의 물리적인 형태나 함수층의 수리성 분석 및 수직인 지질분포를 파악하여 어떤 조건하에서 물이 유입 유출되는가를 파악한 후에만 가능하다. 또한 지하수계의 물리적인 형태를 이해함으로써 조사지역의 지표수계나 지하수계의 양계를 통해서 흐르는 물의 양을 결정짓는 물수지 분석이 수행되어야 한다. 이에 따라 강수량, 증발산량, 지하수 유출량, 지표유출량 그리고 하천유출량 등을 수문학적으로 고려해야만 한다. 본 연구는 지표수-지하수 결합모형을 도입하여 분포형 지하수 함양량의 시공간적인 변동성을 파악하는 데 그 목적이 있다. 이를 위해 지표수-지하수 결합모형인 SWAT-K모형을 미호천 유역에 적용하였으며, 지표수의 총유출량과 지하수위의 공간분포자료를 이용하여 검정과 검증을 수행하였다. 전체유역에 대한 연평균 함양량은 수문총량의 약 19%인 것으로 나타났다. 1999년${\sim}$2004년까지의 소유역별 연간 함양량 결과를 월별로 나타냈으며, HRU(Hydrologic Response Unit)별 함양량의 공간분포를 통해 월별, 계절별 특성을 살펴볼 수 있었다. 소유역 모두 강수가 집중하는 7-9월에 걸쳐 많은 함양이 이루어지며 $1{\sim}3$월에는 상대적으로 함양이 적은 것을 볼 수 있다. 월함양량의 경우 최대 약200mm범위내에서 유역의 토지이용 및 토양특성, 경사등에 따라 매우 비균질하게 분포하는 것을 확인할 수 있었다. 이와같은 함양량의 시공간적 불균일성으로 인해 지하수 관리방안은 소유역별 함양특성을 반영해야 할 것으로 판단된다.의 종분산지수가 일반적인 자연대수층에 비해 9.1배 정도 높다는 것을 의미한다. 이는 시험대수층의 투수성이 매우 높아 염소이온의 용질이송이 매우 빠르게 발생되었기 때문이다. 본 연구에서 추정된 종분산지수를 Gelhar et al.(1992)의 연구 결과와 비교 분석한 결과에서도 시험규모에 비해 매우 높은 수리분산이 발생된 것으로 나타났다. 그리고 염소이온의 확산면적을 추정하기 위해, 수렴흐름 추적자시험에 의한 종분산지수와 시험대수층의 평균선형유속을 이용하여 종분산계수를 구하였다. 현장에서 수행된 양수시험에 의한 평균선형유속 22.44 m/day와 평균 종분산지수 0.4155 m를 적용하여 산정된 종분산계수는 $9.32\;m^2/day$이었다. 따라서, 시험부지 내 충적층에서 일정한 양수율$(2,500\;m^3/day)$로 지하수를 개발할 시에 양수정 주변지역으로 유입되는 염소이온의 확산면적은 1일 $9.32\;m^2$ 정도일 것으로 나타났다.적인 $OH{\cdot}$ 의 생성은 ascorbate가 조직손상에 관여할 가능성을 시사하였다.었다. 정확한 예측치를 얻기 위하여 불균질 조직이 조사야에 포함되는 경우 보정이 요구되며, 골반의 경우 골 조직의 보정이 중요한 요인임을 알 수 있었다. 이를 위하여 불균질 조직에 대한 정확한 정보가 요구되며, 이는 CT 영상을 이용하는 것이 크게 도움이 되리라 생각된다.전시 슬러지층과 상등액의 온도차를 측정하여 대사열량의 발생량을 측정하고 슬러지의 활성을 측정할 수 있는 방법을 개발하였다.enin과 Rhaponticin

• Geophysics and Geophysical Exploration
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• v.10 no.4
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• pp.369-376
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• 2007

Electrical resistivity tomography was carried out at seawater intrusion monitoring wells located at watershed in coastal areas. It is difficult to identify the characteristics of resistivity near monitoring well in case of using high signalto-noise ratio array due to the high conductivity condition in coastal aquifer although electrical resistivity survey is well adopted to delineate hydrogeological characteristics with the distribution of electrical resistivity. To improve the quality of electrical resistivity survey for two sites with seawater intrusion monitoring wells, inversion with the results of holeto-surface electrical resistivity tomography using single well was executed. The results of inversion for aquifer near wells were verified with the results of drilling log with the informations of fracture, electrical conductivity logging and normal resistivity logging. The inversion for aquifer near one of two wells was also performed at low and high tide with the same electrodes, respectively. From the inversion result, it is possible to obtain the resistivity images with high resolution and to identify the characteristics of aquifer related to seawater intrusion with tidal fluctuation. From this study, it was demonstrated that the hole-to-surface electrical resistivity tomography method accompanied with drilling log, electrical conductivity logging and normal resistivity logging would be useful to delineate the hydrogeological structures near monitoring wells in coastal areas.

• Journal of the Korean GEO-environmental Society
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• v.11 no.9
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• pp.15-25
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• 2010

The main objective of this study was to offer informations about long-term seepage behavioral characteristics and to find a leakage safety management method for Juam Dam and Imha Dam, a central cored rockfill dams in Korea by the evaluating the automatically monitored leakage data. In the water leakage monitoring of fill dam, the generation of abnormal water leakage is difficult to directly detect due to the effect of outside factors such as the component of rainfall inherent in the observation value. Therefore, conventionally estimation methods of water leakage quantity were applied by multiple regression analysis considering reservoir water level, rainfall, etc.. However, the estimated error of rainfall component is relatively big in these method. This paper identifies the seepage characteristic of each dams which is not directly affected by rainfall through the hydrograph separation analysis and 3 dimensional analytical method, and thinks a leakage management method. It was noticed that two dams had site specific seepage behaviour features and were in stable state with the decreasing leakage quantity. It was also found that hydrograph separation method might be applicable to leakage safety management method.

• 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 Chemical Society
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• v.36 no.5
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• pp.727-737
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• 1992

The water chemical characteristics and age dating of springwater in Cheju island had been investigated. C_1, C_4, C_7, C_9 springwaters were not affected by seawater intrusion by TDS and electrical conductivity, relationship of Cl and tritium, Cl and HCO_3 ratio, and total hardness and pseudo hardness. In this case only C_7 springwater was evaluated tasty and healthy mineral springwater by Hahimoto's Mineral Balance Index. On the basis of the mean tritium content of rainfalls and springwater, the average residence time of it, were calculated. Considering the hydrogeologic and hydrochemical condition, completely mixed model seems to be very fit. It was obtained the result that C_9 group springwater (C_{10}, C_{12}, C_{14}) was 1.2 months, C_7 springwater was 5.6 months, and deep groundwater C_{17} was 4 years.