• Journal of Soil and Groundwater Environment
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• v.25 no.2
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• pp.16-23
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• 2020

In this work, ²²²Rn activity, major dissolved ions, and microbial community in ground- and surface waters were investigated to characterize groundwater inflow to the stream located in an urban area, Daejeon, Korea. The measured ²²²Rn activities in groundwater and stream water ranged from 136 to 231 Bq L^-1 and 0.3 to 48.8 Bq L^-1, respectively. The spatial distributions of ²²²Rn activity in the stream strongly suggested groundwater inflow to the stream. The change of geochemical composition of the stream water indicated the effect of groundwater discharge became more pronounced as the stream flows downstream. Furthermore, microbial community composition of the stream water had good similarity to that of groundwater, which is another evidence of groundwater discharge. Although groundwater inflow could not be estimated quantitatively in this study, the results can provide useful information to understand interactions between groundwater and surface water, and determine hydrological processes governing groundwater recharge and hydrogeological cycles of dissolved substances such as nutrients and trace metals.

• Journal of the Korean Society of Groundwater Environment
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• v.6 no.2
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• pp.53-58
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• 1999

This study was carried out evaluate to identify water quality and contamination characteristics of the shallow groundwater. and their seasonal variation in the rual area of the Yongin city. Groundwater sample were collected two times (in April and September) from a total of 19 well for domestic water supply. and surface-water samples from six locations. For cations, Ca and Mg predominated. In anion competition. the influence of Cl was obvious in the april samples. However. HCO$_3$ was a major component in the september samples. Electric conductivities and the concentrations of NO$_3$-N in groundwater samples significantly decreased from the april samples to the september samples This indicates a significant seasonal variation in the shallow groundwater composition. When the shallow aquifer is connected to the surface water. then metals sorbed on the stream sediments could occur at nearby wells through the induced recharge. Contaminants at ground surface appeared to be transported to the groundwater system infiltration during the spring melt.

• 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.

• 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 the Korean Society of Environmental Restoration Technology
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• v.10 no.6
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• pp.70-80
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• 2007

This study was surveyed from January to september, 2007 in order to evaluate the function of coastal wetland as a ecological axis in korea peninsula. Assessment was done by RAM (Rapid Assessment Method). RAM is consisted of total 8 contents and divided into high, moderate, low. The preservation grade of RAM is divided into 4 grades; absolute preservation, preservation, improvement and improvement or restoration. Throughout survey on total 14 wetlands of marine, estuary wetland and back marsh which are distributed in west coast in chung-nam province, their function was assessed. As result, total all the 14 wetlands were judged as preservation grade by assessment of 8 functional contents. The function of wetlands assessed as preservation grade showed high in water quality protection and improvement. Also, showed high in vegetation diversity, wildlife habitat and aesthetic recreation. Meanwhile, showed low in ground water recharge, Shoreline/Stream Bank Protection, Flood/Stormwater storage and Flood flow alteration. Of wetlands evaluated as preservation grade, Dae-ho, Sinduri, Bu-Nam lake, Sowhang dune and keum river estuary were assessed as absolute preservative area owing to habitation of international protection species and endangered species. These wetlands are essential to be managed continuously as a area having high ecological value. Farther, this wetlands will be done as a axis of ecological network related to land ecosystem.

• The Journal of Engineering Geology
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• v.14 no.4 s.41
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• pp.469-485
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• 2004

The purpose of this study is to investigate the hydrochemical characteristics of groundwater in the Umsung area, and to elucidate the effect of host rock type, well depth and mineralization zone on the groundwater chemistry. The geology of the study area consists of Jurassic granite and Cretaceous sedimentary rocks, which are bounded by a fault. Most of shallow groundwaters exploited in the Jurassic granite area are used for agricultural purpose, whereas the deep groundwaters in the Cretaceous sedimentary rocks are used for a drinking water. The shallow groundwater shows weak acidic pH, the electrical conductivity ranging from $142\;to\;903\;{\mu}S/cm$, and the chemical type of $Ca-HCO_3\;to\;Ca-Cl(SO_4,\;NO_3)$. A few of shallow groundwaters are contaminated by nitrate, and show high concentration of Fe, Mn and Zn, that reflects the effect of a mineralization zone. The deep groundwater shows neutral to weak alkaline pH, higher electrical conductivity than that of shallow groundwater, and the chemical type of $Ca-HCO_3$. The seepage water from the abandoned mines does not have the characteristics such as acidic pH, high concentration of heavy metals and high sulfate content. The hydrogen and oxygen isotopes of groundwater indicates an altitude effect of the recharge area between deep groundwater and shallow groundwater. In conclusion, the chemical composition of groundwater complicately reflects the effects of their host rocks, well depth, agricultural activity and mineralization zone in the study area.

• The Journal of Engineering Geology
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• v.22 no.2
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• pp.195-205
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• 2012

We evaluated the results of pumping tests, the amount of groundwater used by Protected Cultivation with Water Curtain (PCWC), and monthly depth to water table (DTW) at the Wangjeon-ri area, Nonsan City, to elucidate the cause of a decrease in pumping rate during the winter PCWC season. The transmissivity and storage coefficient at eight sites where the major aquifer is alluvium, vary from 119.9 to $388.1m^2/d$ and $1.5{\times}10^{-4}$ to $5.5{\times}10^{-4}$, respectively. The pumping rate for PCWC during three months (Dec. to Feb.) averaged about $8,100m^3/d$ and the maximum water level in the area varied by about 10 m. Groundwater levels had fully recovered by August-five months after pumping for PCWC had ceased. These observations indicate that the pumping rate during the winter PCWC season was excessive compared with groundwater productivity in the area. Groundwater level in the central PCWC area varied from -3.0 to 4.38 m, exceeding the water level of the Nosung Stream for only three months (Aug. to Oct.). This result indicates that Nosung Stream recharges the area during the period from November to July. To solve the problem of reduced pumping rate during the winter PCWC season, it would be necessary to reduce the amount of groundwater used for PCWC or to develop an artificial recharge system using recycled groundwater.

• The Journal of Engineering Geology
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• v.25 no.2
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• pp.215-225
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• 2015

We performed injection tests in a deep-seated confined aquifer to assess the potential of artificial recharge as a means of preventing saltwater contamination, thereby securing groundwater resources for the Nakdong Delta area of Busan City, Korea. The study area comprises a confined aquifer, in which a 10-21-m-thick clay layer overlies 31.5-36.5 m of sand and a 2.8-11-m-thick layer of gravel. EC logging of five monitoring wells yielded a value of 7-44 mS/cm, with the transition between saline and fresh water occurring at a depth of 15-38 m. Above 5 m depth, water temperature is 10-15.5℃, whereas between 5 and 50 m depth the temperature is 15.5-17℃. Approximately 950 m³ of fresh water was injected into the OW-5 injection well at a rate of 370 m³/day for 62 hours, after which the fresh water zone was detected by a CTD Diver installed at a depth of 40 m. The persistence of the fresh water zone was determined via EC and temperature logging at 24 hours after injection, and again 21 days after injection. We observed a second fresh water zone in the OW-2 well, where the first injection test was performed more than 20 days before the second injection test. The contact between fresh and saline water in the injection well is represented by a sharp boundary rather than a transitional boundary. We conclude that the injected fresh water occupied a specific space and served to maintain the original water quality throughout the observation period. Moreover, we suggest that artificial recharge via long-term injection could help secure a new alternative water resource in this saline coastal aquifer.

• Journal of Soil and Groundwater Environment
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• v.9 no.3
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• pp.38-48
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• 2004

Natural attenuation of petroleum hydrocarbon was investigated at an industrial complex about 45 Km away from Seoul. The three-years monitoring results indicated that the concentrations of DO, nitrate, and sulfate in the contaminated area were significantly lower than the background monitoring groundwater under the non-contaminated area. The results also showed a higher ferrous iron concentration, a lower redox potential, and a higher (neutral) pH in the contaminated groundwater, suggesting that biodegradation of TEX(Toluene, Ethylbenzene, Xylene) is the major on-going process in the contaminated area. Groundwater in the contaminated area is anaerobic, and sulfate reduction is the dominant terminal electron accepting process in the area. The total attenuation rate was about 0.0017∼0.0224day$^{-1}$ and the estimated first-order degradation rate constant(λ) was 0.0008∼0.0106day$^{-1}$ . However, the reduction of TEX concentration in the groundwater was resulted from not only biodegradation but also dilution and reaeration through recharge of uncotaminated surface and groundwater. The natural attenuation was, therefore, found to be an effective, on-going remedial process at the site.

• Journal of Soil and Groundwater Environment
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• v.7 no.3
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• pp.3-17
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• 2002

Data analysis of groundwater monitoring wells and geostatistical methods are used to identify the local characteristics of sea water intrusion and the range of sea water intrusion at the southeastern coastal area of Busan, Korea. Rainfall and groundwater level of two monitoring wells show a linear correlation because of the direct groundwater recharge by the precipitation. However, rainfall and electric conductivity have the inverse relationship because of the increase of groundwater. Electric conductivity rapidly increased at 24m depth and exceeded 20,000$\mu\textrm{s}$/cm near 26m depth in the monitoring wells. The variations of groundwater level and electric conductivity show that the interface between sea water and fresh water tends to move upward when groundwater level goes down. In the cross correlation analysis, groundwater level versus rainfall represents the largest cross correlation coefficient in 0 time lag but the cross correlation coefficient of electric conductivity versus rainfall is the largest when the time lag is 9 days. This suggests that the fluctuations of groundwater level respond to rainfall in a short time, but the interface between sea water and fresh water respond very slow to rainfall. Horizontal extents of sea water intrusion are estimated to 14 m from the east of Line 1, and 25 m from the southeast end of Line 2 in the inversion of dipole-dipole profiling data of two survey lines. The data of VES by the Schulumberger array in May and July show lognormal distributions. In the kriged apparent resistivity and earth resistivity distributions, the resistivities of July are increased comparing to those of May. This reflects that the concentration of sea water in aquifer is reduced due to the increased groundwater recharge from the rainfall in June and July. In analyzing the vertical and horizontal apparent resistivities and earth resistivity distributions, the geostatistical methods are very useful to identify the variations of earth resistivity distributions at the coastal area.