• The Journal of Engineering Geology
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• v.3 no.3
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• pp.267-278
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• 1993

Ground-water temperature is one of the parameters for observing diarges in the state of the ground-water regime in time and space, which relate to conditions for recharge as well as the influence of various natural and man-induced fadors on the regime. Because ground-water satura tes much of the rock materiats in the upper layer of the earth's csust the water temperature reflects in part the temperature of the water-bearing rocks. The mobffity and thennal capadty of groud-waters, however, serves to redistribute some of the heat within the stratosphere and to influence the developement of the geothermal regime within this sphere. The utilization of temperature data of the study area(25 points) in the solution of hydrogeologic problems requires an understanding of some of the fundamental aspects of subsurtice temperatures. These include the depth of penetration of heat waves generated of the surtace, the rate of propagation of the waves, and the geothermal gradient in the study area of Taegu.

• 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.

• The Journal of Engineering Geology
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• v.24 no.2
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• pp.217-225
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• 2014

Water curtain cultivation (WCC) systems in Korea have depleted water resources in shallow aquifers through massive pumping of groundwater. The goal of this study is to simulate the groundwater variations observed from massive groundwater pumping at a site in Cheongweon. MODFLOW was used to simulate three-dimensional regional groundwater flow, and the SWAT (Soil and Water Assessment Tool) watershed hydrologic model was employed to introduce temporal changes in groundwater recharge into the MODFLOW model input. Additionally, the estimation method for groundwater discharge in WCC areas (Moon et al., 2012) was incorporated into a groundwater pumping schedule as a MODFLOW input. We compared simulated data and field measurements to determine the degree to which winter season groundwater drawdown is effectively modeled. A simulation time of 107 days was selected to match the observed groundwater drawdown from November, 2012 to March, 2013. We obtained good agreement between the simulated drawdown and observed groundwater levels. Thus, the estimation method using daily minimum temperatures, may be applicable to other cultivation areas and can serve as a guideline in simulating the regional flow of riverside groundwater aquifers.

• The Journal of Engineering Geology
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• v.25 no.1
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• pp.67-81
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• 2015

A FORTRAN program was developed to determine the optimal locations of multiple recharge wells in an aquifer with different arrangements of pumping wells. The simulated annealing algorithm was used to find optimal locations of two recharge wells which satisfied three objective functions. The model results show that locating two injection wells inside the cluster of pumping wells is efficient if the recovery rate only was taken into account. In contrast, placing injection wells to the side of the cluster is desirable if the simulation considers aggregate objective function. Therefore, installing an injection well on each side of the cluster seems to yield the maximum recovery rates for the existing pumping wells, and it yields similar increases in pumping rate for all wells in the cluster. The locations of recharge wells can be arranged in numerous configurations, because there are multiple near-optimal local minima or maxima. These results indicate that the simulated annealing can yield effective evaluations of the optimal locations of multiple recharge wells. In addition, the suggested aggregate objective function can be utilized as an appropriate multi-objective optimization.

• Spatial Information Research
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• v.4 no.1
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• pp.1-11
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• 1996

DRASTIC system developed by U.S.EPA, is widely used for assessing groundwater pollution potential The system can be applied to site selection of well or waste disposal, Ianduse planning for groundwater protection, and monitoring. In this study, GIS(Geographic Information System) was established hydrogeological database of DRASTIC system and cartographic modeling to asre:; regional groundwater pollution potential around Chungju Lake. Hydrogeological factors of the system were depth to water, net recharge, aquifer media, soil media, slope and hydraulic conductivity. Risk of groundwater pollution to non -point source pollution, was also analyzed by incorporation of actual pollution sources(N, P) and DRASTIC system. The GIS data could be very quickly analysed hydrogeological characteristics of the study area by graphic user interface programs devel¬oped with AML(ARC Macro Language) of ARC/INFO.

• Journal of Soil and Groundwater Environment
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• v.8 no.3
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• pp.74-85
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• 2003

To increase the yield from groundwater wells in various rock types by hydrofracturing, tests of 12 wells were carried out as a part of sustainable groundwater development and artificial recharge project. Test wells are selected 5 wells in Jurassic granites, 2 wells in Cretaceous volcanics, 4 wells in Cretaceous sedimentary rocks and one well in Pre-Cambrian gneiss. The results show that specific capacity of II wells increased about 7% to 366%, while a well in Cretaceous sedimentary rock decreased about 43.4% owing to plugging of fault clay. Meanwhile, impact distances influenced due to hydrofracturing ranged from 5.4 m to 82.7 m from the test wells, actual drawdown data measured during the pumping test after hydrofracturing are more or less decreased and reveals balanced drawdown.

• Journal of Wetlands Research
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• v.15 no.2
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• pp.179-189
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• 2013

The Haean basin is a unique geographical feature formed by differential erosion and it borders the military demarcation line. Recently the basin has become an interest of civilians due to security tour, highland vegetables and wetland. After the civil war, the population decreased but it has increased since 2007. The annual mean air temperature in the basin has increased with a rate of $+0.016^{\circ}C/yr$ and the annual precipitation also has increased with a rate of +10.41 mm/yr. The precipitation occurring in June~August (wet season) occupied most of the total precipitation increase. In addition, recently the number of groundwater wells and its use have gradually increased and most of them are for agriculture including cultivation of rice and highland vegetables. If the air temperature further increases in the future according to the climate change scenarios, the highland vegetables cultivation will be difficult. Furthermore, if the rainstorm in the summer will be enforced, the groundwater recharge and water management will be aggravated. Therefore, an evaluation for sustainable groundwater development in the basin and a reform of the current agriculture (change of cultivating crops) depending on much water are essentially required.

• 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.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.26-26
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• 2012

The Kurobe river, which runs through eastern Toyama Prefecture is one of the most famous rivers for wild water because of its steep slope in the range from 1/5 to 1/120. This river forms an alluvial fan in the range up to 13 kilometers from the sea. In this region, significant seepage flow occurs and thus the stream sometimes been intermitted. Moreover, the amount of seepage flow seems to vary with the groundwater level of the region. To keep the river environment healthy for flora and fauna, especially to conserve good condition for spawning of fishes, an appropriate environmental flow should be maintained in the river. To achieve this target, controlling of the upstream reservoir has to be studied in depth. One of the major problems to decide the amount of water to be released from the reservoir to maintain the environmental flow is to estimate the amount of water leaked into the groundwater from the river. This phenomenon is affected by the river flow rate as well as the groundwater level in the alluvial fan and the conditions vary in space and time. Thus, a grid-based hydrological cycle analysis model NK-GHM has been applied to clarify the hydrological cycle componentsin this area including seepage/discharge from/to the river. The model was tested by comparing with river flow rate, groundwater levels and other observations and found that the model described those observations well. Consequently, the seepage from the Kurobe river was found significant but it was also found that the groundwater in this region has been preserved by the recharge from the irrigation water supply into paddy fields in the alluvial fan.

• Journal of Korean Society on Water Environment
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• v.27 no.4
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• pp.405-412
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• 2011

Increased Non-permeable areas which have resulted from civilization reduce the volume of groundwater infiltration that is one of the important factors causing water shortage during a dry season. Thus, seeking the efficient method to analyze the volume of groundwater in accurate should be needed to solve water shortage problems. In this study, two different watersheds were selected and precipitation, soil group, and land use were surveyed in a particular year in order to figure out the accuracy of estimated infiltration recharge ratio compared to Web-based Hydrograph Analysis Tool (WHAT). The volume of groundwater was estimated considering Antecedent soil Moisture Condition (AMC) and Curve Number (CN) using Long Term Hydrologic Impact Assessment (L-THIA) model. The results of this study showed that in the case of Kyoung-an watershed, the volume of both infiltration and baseflow seperated from WHAT was 46.99% in 2006 and 33.68% in 2007 each and in Do-am watershed the volume of both infiltration and baseflow was 33.48% in 2004 and 23.65% in 2005 respectively. L-THIA requires only simple data (i.e., land uses, soils, and precipitation) to simulate the accurate volume of groundwater. Therefore, with convenient way of L-THIA, researchers can manage watershed more effectively than doing it with other models. L-THIA has limitations that it neglects the contributions of snowfall to precipitation. So, to estimate more accurate assessment of the long term hydrological impacts including groundwater with L-THIA, further researches about snowfall data in winter should be considered.