• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.113-114
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• 2004

In order to classify the groundwater recharge characteristics in an urban area, a time series analysis of groundwater level data was performed. For this study, the daily groundwater level data from 35 monitoring wells were collected for 3 years (Fig. 1). The use of the cross-correlation function (CCF), one of the time series analysis, showed both the close relationship between rainfall and groundwater level change and the lag time (delay time) of groundwater level fluctuation after a rainfall event. Based on the result of CCF, monitored wells were classified into two major groups. Group I wells (n=10) showed a fast response of groundwater level change to rainfall event, with a delay time of maximum correlation between rainfall and groundwater level near 1 to 7 days. On the other hand, the delay time of 17-68 days was observed from Group II wells (n=25) (Fig. 1). The fast response in Group I wells is possibly caused by the change of hydraulic pressure of bedrock aquifer due to the rainfall recharge, rather than the direct response to rainfall recharge.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.04a
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• pp.225-228
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• 2003

For the purpose of finding out the distributions of groundwater uses, the effect of facilities on the parameter and the correlations among measurements, various statistical analysis were carried out with the data of groundwater quality measurements from January to December in 2002. 1. The rates of groundwater for drinking water were 10.5% in Yangcheon-Gu, 10.2% in Kangdong-Gu, and 9.9% in Eunpyung-Gu. The rates of other uses of groundwater were shown to be 58.1%(786 wells) for civil defense emergency, 22.1%(299 wells) for contamination-concerning, 9.8%(133 wells) for water quality monitoring, consisting of 90% of all groundwater. 2. The 52.6% of groundwater for drinking were demonstrated to be appropriate while 91.9% for tither uses-domestic, industrial, agricultural uses- were shown to be proper. 3. For drinking water, the average values of colar, turbidity, NH3-N, F, and Fe were 11.216 degree, 2.138 NTU, 2.458mg/l, 0.212mg/1 and 0.507mg/1 respectively. 4. In cases of drinking water wells for emergency, the results of statistical analysis showed that building year of the wells, depth and pumping rate didn't affect on whether it was proper for that use or not. It were shown that there were linear correlations between depth and NO$_3$-N(-0.171) and F￣(0.332) while the correlation coefficients were 0.381 and -0.169 between the building year of well and depth and pumping rate respectively.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.04a
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• pp.213-216
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• 2002

To investigate the conditions of groundwater resources in Jeonju, Wanju, and Goksung areas, a basic groundwater survey was performed. From the survey, various useful informations such as groundwater use, waterlevel distribution, water chemistry were obtained. This study focused on the analysis of the water levels, which were automatically monitored with pressure transducers or manually measured. The monitorings were conducted for both shallow wells completed in alluvial aquifers and deep wells in bedrock aquifers. This study presents results of the investigation.

• KCID journal
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• v.7 no.2
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• pp.57-65
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• 2000

The effect of land use of an alluvial watershed in the upper North Han river basin on groundwater quality were investigated. Existing 20 farm wells were selected as monitoring wells representing different land uses of residential, arable(paddy and field),

• Journal of the Korean earth science society
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• v.41 no.4
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• pp.381-390
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• 2020

When a radial collector well is installed and operated for agricultural purposes, negative impacts may be observed over time due to the clogging of horizontal arms, such as reduced groundwater discharge and water quality deterioration. When radial collector well No. 2 was rehabilitated using the high-pressure impulse generation technique, the specific capacity and transmissivity were increased by 43.1 and 100.6%, respectively. In contrast, according to air surging, the specific capacity and transmissivity increased by 33.8 and 85.8%, respectively, compared to the initial rate before rehabilitation. During the operation of radial collector wells since construction, the time of well rehabilitation can be effectively determined by continuously monitoring the groundwater level and pumping rate of the radial collector wells, thereby preventing a decrease in productivity.

• Journal of Soil and Groundwater Environment
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• v.23 no.3
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• pp.1-9
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• 2018

This study is aimed to quantitatively evaluate the effects of drought on groundwater system in rural areas. For this purpose, the standardized groundwater level index (SGI) was used for 68 groundwater monitoring wells. To determine accumulation period (AP) which represents the month with the highest correlation coefficient between SGI and SPI, correlation analysis between the two for 68 wells were peformed. The results indicated the AP values ranged in 1~3 months for most of the well, but it was 7~10 months in some wells. These results can be interpreted such that the total amount of groundwater will not decrease significantly in long-term drought situations unlikely the reservoirs with the high AP values. The nationwide maximum AP values were 4.1 and 4.0 in Chungbuk-do and Gyeongnam-do, while the minimum AP values were 1.8 and 2.0 in Gangwon-do and Chungnam-do, respectively. The maximum and minimum values of correlation coefficient were 0.623 and 0.459 in Gyeongnam-do and Chungnam-do/Chungbuk-do, respectively. Consequently, it could be concluded that the wells with low AP value tend to respond to short-term drought, but it has little effect on groundwater system when the long drought occurs.

• Economic and Environmental Geology
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• v.36 no.1
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• pp.49-58
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• 2003

To analyze the anisotropic characteristics of fractured aquifer, variations of streaming potential were measured during and after pumping over several wells at the two test sites. Surface electrical resistivity survey, normal resistivity logging, and slug test were performed at the wells to identify the hydrogeological structure. Applying the results to the recently suggested model, the aquifer of the two test sites showed confined characteristics. Anisotropic direction appeared in using equi-potential maps from self-potential monitoring results matched well with the results of the hydrogeological test. The self-potential monitoring method adopted in this study would be useful for providing a more reliable information on the anisotropy of aquifer in the pumping test at single well.

• Economic and Environmental Geology
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• v.44 no.3
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• pp.239-246
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• 2011

Groundwater in small islands is used as main water resource but the overuse of groundwater may cause seawater intrusion and temperature decrease in geothermal wells. This study aimed to characterize the hydrogeology of Maeum-ri area in Seokmo Island of Ganghwagun using long-term monitoring at groundwater wells and geothermal wells. In the monitoring period seasonal water level change, consistent drop or increase of water levels are not detected. The groundwater temperature about 10m below ground surface shows year cycle variation having two to five months difference with ambient temperature cycle. The storativity was calculated by tidal method. The storativity estimated by adapting tidal efficiency factor showed some larger values than that by using tidal time lag. The result suggested that the tidal method assuming several assumptions on aquifer condition may produce broad ranges but the calculated ranges at this application are reasonable. The similar shape of groundwater level change and tidal effects was observed at several wells clustered east-south-east direction which may implicate the distribution of vertical fracture system strongly related with groundwater flow channels. The applied methodology and study results will bc valuable to evaluate optimal pumping rate for the preservation of groundwater resources, and to manage geothermal development.

• Journal of the Korean GEO-environmental Society
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• v.11 no.3
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• pp.5-16
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• 2010

Groundwater quality monitoring wells, which is over 2,000 in South Korea, were managed to observe groundwater quality since the early 1990s. Groundwater was sampled and analyzed biannually from 781 monitoring wells located in the areas with a high possibility of pollution. The average concentrations of cyanide, mercury, phenols, hexavalent chromium, trichloroethylene, tetrachloroethylen, and 1.1.1-trichloroethane for 12 years' data of detected cases were above the groundwater quality standard, but the average concentrations of the general quality items such as pH, electric conductivity, nitrate-nitrogen, and chloride, are below the standard. To compare a quality trend for each land-use type of the monitoring site, Sen's method is used for four quality items; chloride, nitrate-nitrogen, pH, and electric conductivity. The upward trend for these items is remarkable in urbideareas and industrial complexes and this trend continues still strongly after 2001. The deviation in a trend slopes of monitoring wells becomes bigger in the mid-2000s. In conclusion, trend analysis using existing monitoring data cidebe effective to forecast the future water quality condition and the solid action to protect groundwater quality should be done in advance using a result of trend analysis.

• Economic and Environmental Geology
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• v.40 no.4
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• pp.403-418
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• 2007

The objective of this research was to characterize the fate and transport of Cr(VI) contaminated groundwater in the Daejeon industrial area. Five subsidiary monitoring wells were newly installed and two existing wells were utilized for the investigation and the reduction process of Cr(VI) contaminated groundwater of the Daejeon(Mun-pyeong) national groundwater monitoring station. The Cr(VI) concentrations at the shallow aquifer well of the station were in the range of 3.2-4.5 mg/L indicating continuous contamination. However, Cr was not detected at the deep bedrock well and the other monitoring wells except MPH-1 and 3. The Cr(VI) concentrations of MPH-1 and MPH-3 were below the drinking water guideline value (0.05 mg/L). Therefore, the plume of the Cr(VI) contaminated groundwater was predicted to be confined within the narrow boundary around the station. The soluble/exchangeable Cr(VI) concentrations were below the detection limit in all core and slime samples taken from the five newly installed wells. Although the exact source of contamination was not directly detected in the study area, the spatial Cr(VI) distribution in groundwater and characteristics of the core samples indicated that the source and the dispersion range were confined within the 100 m area from the monitoring station. The contamination might be induced from the unlined landfill of industrial wastes which was observed during the installation of an subsidiary monitoring well. For the evaluation of the natural attenuation of Cr(VI), available reduction capacities of Cr(VI) with an initial concentration of 5 mg/L were measured in soil and aquifer materials. Dark-gray clay layer samples have high capacities of Cr(VI) reduction ranging from 58 to 64%, which is obviously related to organic carbon contents of the samples. The analysis of reduction capacities implied that the soil and aquifer materials controlled the dispersion of Cr(VI) contamination in this area. However, some possibilities of dispersion by the preferential flow cannot be excluded due to the limited numbers of monitoring wells. We suggest the removal of Cr(VI) contaminated groundwater by periodical pumping, and the continuous groundwater quality monitoring for evaluation of the Cr(VI) dispersion should be followed in the study area.