• Geophysics and Geophysical Exploration
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• v.8 no.2
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• pp.156-162
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• 2005

Particularly in research related to seawater intrusion the change of fluid electrical conductivity is one of major concerns, and effective monitoring can help to optimize a water pumping performance in coastal areas. Special considerations should be given to the mounting of sensors at proper depth during the monitoring design since the vertical distribution of fluid electrical conductivity is sensitive to the characteristics of seawater intrusion zone. This tells us the multi-channel electrical conductivity monitoring is of paramount consequence. It, however, is a rare event when this approach becomes routinely available in that commonly used commercial stand-alone type sensors are very expensive and inadequate for a long term monitoring of electrical conductivity or water level due to their restricted storage and difficulty of real-time control. For this reason, we have developed a real-time monitoring system that could meet these requirements. This system is user friendly, cost-effective, and easy to control measurement parameters - sampling interval, acquisition range, and others. And this devised system has been utilized for the electrical conductivity monitoring in boreholes, Yeonggwang-gun, Korea. Monitoring has been consecutively executed for 24 hours, and the responses of electrical conductivity at some channels have been regularly increased or decreased while pumping up water. It, with well logging data implemented before/after pumping water, verifies that electrical conductivity changes in the specified depths originate from fluid movements through sand layer or permeable fractured rock. Eventually, the multi-channel electrical conductivity monitoring system makes an effective key to secure groundwater resources in coastal areas.

• The Journal of Engineering Geology
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• v.16 no.2 s.48
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• pp.125-134
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• 2006

In order to establish the in-situ application of the artificial storage and recovery (ASR) technology which is used the property of the aquifer storage of groundwater. We carried out to the in-situ experiments such as borehole TV logging, pumping test and artificial hydraulic fracturing in volcanic island, Ulleungdo. In-situ experiments were conducted to divide the before- and after-hydraulic fracturing. Pumping test was achieved to confirm the two fracture zones, GL-13m and GL-21m, which are determined by the borehole TV logging. From the results of the before- and after-pumping tests, the hydraulic connectivity was confirmed to locate at GL-13m in the residual deposit zone of pumice media as alluvium. However, in the bedrock tone at GL-21m the hydraulic connectivity could be considered to faulty. Consequently, in this study area the artificial recharge has a little unsatisfied to geo-structural condition and desired to more detail investigation works.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.174-179
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• 2006

본 연구에서는 지하철 노선, 지하수 양수량 및 상수도 누수량 등 도시유역에서 물순환에 큰 영향을 미치는 인공적 요소들을 분포형 수문모형에 반영하여 물순환을 모의하였다. 분포형 수문모형으로는 일본토목연구소에서 개발된 WEP 모형을 사용하였다. 입력자료 구축시 지하철 노선을 따라서 제1투수층, 제1난투수층, 제2투수층의 투수계수를 낮게 설정하여 지하철 노선의 영향을 반영하였으며, 지하철역 및 구별 지하수 양수량, 상수도 누수량을 모형의 입력자료로 구축하였다. 모의결과를 서울시 지하수관측공의 실측 자료와 비교하여 양호한 결과를 얻을 수 있었으며, 유역 스케일에서의 지하수위 분포양상을 모의할 수 있었다. 지하철 노선, 지하수 양수량, 상수도 누수량 등을 고려, 미고려시를 별도로 모의하여 각각 요소가 물순환에 미치는 개별적 종합적 영향에 대해 평가하였다.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2002.10a
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• pp.393-396
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• 2002

The objectives of the paper are to develop the infra-technologies for reclaiming the effluents from wastewater treatment plants and reusing for agriculture water. The Suwon wastewater treatment plant has been selected for wastewater reuse tests and the water quality and treatment efficiencies are investigated. Three levels of wastewater treatments that are the effluent from the plant, sand filtering, and ultra-violet treatment are applied in the pilot system. The randomized block method was applied to wastewater application to paddy rice with five treatments, three blocks, and two replica. The control was the plots with groundwater irrigation, the other treatments are to use polluted stream flow by pumping, in addition to three wastewater treatments. The block test plots and field plots have been monitored for the water quality, soil pollution, and health hazards during the crop stages.

• Proceedings of the Korean Geotechical Society Conference
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• 2001.03a
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• pp.405-410
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• 2001

Bioremediation is a degradation process of existing organic contaminants in soils and groundwater by indigenous or inoculated microorganisms. This process can provide economical solution as well as safe and effective alternative in remediation technologies. However, it has been suggested that the rate of bioremediation process of organic contaminants by microorganisms can be limited by the concentration of nutrients and TEAs(Terminal Electron Accepters). In in-situ bioremediation, conventional pumping techniques have been used for supplying these additives. However, the injection of these additives is difficult in low permeable soils, and also hindered by preferential flow paths resulting from heterogeneities in high permeable ground. Therefore, the Injection of chemical additives is the most significant concern in in-situ bioremediation. Most recently, electrokinetic technique has been applied into the bioremediation and the injection characteristics under electrokinetics have not been examined in various soil types. Therefore, in this study, electrokinetic injection method is investigated in kaolinite and sand, and the concentration of ammonium(nutrients) and sulfate(TEAs) in soil is presented.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.3 no.2
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• pp.39-51
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• 2007

Unconsolidated and permeable alluvial deposit composed of sand and gravel is distributed along the fluvial plain at the Iryong study area. Previous studies on the area show that a single alluvial well can produce at least 1,650m3d-1 of bank infilterated shallow groundwater(BIGW) from the deposit. This study is aimed to evaluate and simulate the influence that seasonal variation of water levels and temperatures of the river have an effect on those of BIGW under the pumping condition and also to compare seasonal variation of COPs when indirectly pumped BIGW or directly pumped surface water are used for a water to water heat pump system as an heat source and sink using 3 D flow and heat transport model of Feflow. The result shows that the magnitude influenced to water level of BIGW by fluctuation of river water level in summer and winter is about 48% and 75% of Nakdong river water level separately. Seasonal change of river water temperature is about $23.7^{\circ}C$, on other hand that of BIGW is only $3.8^{\circ}C$. The seasonal temperatures of BIGW are ranged from minimum $14.5^{\circ}C$ in cold winter(January) and maximum $18.3^{\circ}C$ in hot summer(July). It stands for that BIGW is a good source of heat energy for heating and cooling system owing to maintaining quite similar temperature($16^{\circ}C$) of background shallow groundwater. Average COPh in winter time and COPc in summer time of BIGW and surface water are estimated about 3.95, 3.5, and about 6.16 and 4.81 respectively. It clearly indicates that coefficient of performance of heat pump system using BIGW are higher than 12.9% in winter time and 28.1% in summer time in comparision with those of surface water.

• The Journal of Engineering Geology
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• v.18 no.2
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• pp.185-190
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• 2008

Nine wells have been developed for uses of thermal waters at the Icheon hot spa area. Drilling depths of those hot spring wells range from 166 to 294 m and their piezometric heads are located at about 50 m below the surface. Using the differences between the surface and bottom temperatures within all boreholes, we can simply estimate geothermal gradient in this area. Thus, we obtained the highest, lowest and average gradient values as $64^{\circ}C/km$ from SB-2 well, $45^{\circ}C/km$ from SB-1 well and approximately $54.28^{\circ}C/km$, respectively. However, observing the MRD-2 well additionally drilled into the depth of 996 m, we found out that this study area has widely experienced the temperature disturbance due to thermal groundwater penetration through the fracture systems within the depth of 720 m. Unlikely this phenomenon, we can conclude that the groundwater flow below the depth of 720 m does not exist. Therefore, using only those temperature data below the 720 m depth, we can estimate reasonable geo-thermal gradient values as $33^{\circ}C/km$ in this study area. Pumping test shows that outflowing temperature is $36^{\circ}C$ corresponding to the temperature logging data at 720 m depth.

• Journal of Soil and Groundwater Environment
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• v.14 no.5
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• pp.41-50
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• 2009

Water levels in groundwater monitoring wells of Jeju Island were analyzed using parametric and non-parametric trend analyses. Number of used monitoring wells in the analysis are 94 among totally 106 monitoring wells and the monitoring period is greater than single year, from 2001 to 2009. For the trend analysis, both parametric (linear regression) and nonparametric (Mann-Kendall trend test and Sen's trend test) methods were adopted. Results of the linear regression analysis on daily basis indicated that about 58.5% of the monitoring wells showed a decreasing trend, and analysis using monthly median indicated that about 79.8% showed a decreasing trend. The Mann-Kendall trend test and Sen's trend test with monthly median values in confidence levels of 95% and 99% showed the same analysis results. In confidence level of 95%, 32% were decreased, 3% were increased and the remains showed no trend. However, in confidence level of 99%, 16% were decreased, 2% were increased and the remains showed no trend. The largest decline rates of water levels were detected mainly at the coast of the northwestern and southwestern parts, which is expected to closely related to the increased pumping in the urban area and tourist resort.

• Journal of Korea Water Resources Association
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• v.33 no.6
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• pp.765-774
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• 2000

The purpose of this study are to develop a realistic methodology to estimate agricultural water supply for rice paddy fields from reservoirs, pumping stations, intake structures, and tube wells on river basin scale. Agricultural water supply from irrigation reservoirs are estimated using the daily or ten day's storage rate data and DIROMmaily Inigation Reservoir Operation Model) model. Estimation of daily water supply from pumping station are carried out from the annual water use with typical water supply patterns. The daily groundwater withdrawn are investigated from the gross water requirement for rice and the design capacity of tube well. And, the daily intake discharge are estimated the minimum amount from the gross water requirement, stream discharge, and the design capacity. During 1993 to 1997, the annual water supply for irrigation in the Han river basin ranged from 569 to 709 million $\textrm{m}^3/yr$, and the mean was estimated to be 640 million $\textrm{m}^3/yr$.

• The Journal of Engineering Geology
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• v.12 no.2
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• pp.151-166
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• 2002

Groundwater development as a means of acquiring subsidiary water resource is very important for the persistent security of water resource. Nowadays, pneumatic fracturing technology which was developed in the advanced countries is applied for increasing pumping rate and eliminating contaminants. This study gives an experimental data to clarify permeability characteristics of the single discontinuity which is newly developed or increased in aperture by the pneumatic fracturing or damage propagation of the natural barrier for the nuclear waste disposal. On the basis of understanding the relationship between permeability and hydraulic aperture the result could apply as one of the basic data for researches concerned with increasing pumping rate and eliminating contaminants. Hydraulic aperture is decreased exponentially with increasing confining pressure and proportioned to permeability in the same confining pressure. Especially, with the increasing aperture permeability of coarse- and medium- grained granite shows the more rapid increasing than that of fine- grained granite.