• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 추계학술발표회
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• pp.213-216
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• 2003

Efforts for better understanding of the interaction between groundwater recharge and thermal regime of the subsurface medium is gaining momentum for its diverse applications in water resources. A numerical model is developed to simulate temperature variations of the subsurface under time varying groundwater recharge. The model utilizes MacCormack scheme for finite difference approximation of the partial differential equation describing the conductive and advective heat transport. For the estimation of recharge rate, optimization of the model is realized by searching for the unknown parameters which minimize the root-mean-square error between simulated and measured temperatures. Simulation results for 22-year time series data of temperature measurements reveal that the proposed model can accurately simulate subsurface temperature variations resulting from the redistribution of the heat due to the movement of water and it can also estimate temporal variations of recharge. Seasonal variations of recharge and a linear relationship between precipitation and recharge are clearly reflected in the simulated results.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2004년도 학술발표회
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• pp.691-695
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• 2004

In recent years, mary studies for efact estimation of groudwater recharge has been performed. They can be categorized into three groups : analytical method by means of groundwater recession curve, water budget analysis based on watershed, and the method using groundwater model. Since groundwater recharge rate shows the spatial-temporal variability due to hydrogeological heterogeneity, existing studies have various limits to deal with these characteristics. The method of estimating daily recharge rate with spatial-temporal variation based on rainfall-runoff model is suggested in this study for this purpose. This method is expected to enhance existing indirect method by means of reflecting climatic conditions, land use and hydrogeological heterogeneity.

• 지질공학
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• 제21권4호
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• pp.305-312
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• 2011

지하수 함양량은 기후조건, 토지이용, 수리지질학적 비균질성에 의해 시공간적인 변동성을 나타내는 수문량이므로 통합지표수-지하수 모델 기반의 시공간변동성을 갖는 일단위 함양량의 추정이 필요하다. 진천지역을 대상으로 SWAT-MODFLOW 통합모형이 일단위 함양량 추정에 사용되었으며 추정된 함양량의 시변성은 국가 지하수 관측망과 기초조사 기간(2009-2010)중에 설치된 자동관측망 자료와 잘 부합하는 것을 확인하였다. 진천지역을 포함한 미호천 유역 평균 지하수 함양률은 강수대비 20.8%로 나타났는데 이는 해석적 방법인 기저유출 분리법의 결과와도 잘 일치하였다. 통합모델링 기반의 함양량 산정은 국가 지하수 관리를 위해 유용하게 활용될 수 있을 것으로 판단된다.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 추계학술발표회
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• pp.515-518
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• 2003

Groundwater recharge rate can be estimated from groundwater head rebound due to rainfall. Groundwater level changes are monitored for 10 months at Yugu area. Difference between two recharge rates calculated by rainfall and by effective rainfall is 1.1%~1.6%. Since this method ignores soil water percolation during groundwater level regression, the actual recharge rate may be higher than estimated one by cumulative rainfall and groundwater level change.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2002년도 추계학술발표회
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• pp.28-31
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• 2002

The water level fluctuation (WLF) method is a conventional method for quantifying groundwater recharge by multiplying the specific yield to the water level rise. A 2-D unconfined flow model with a time series of the recharge rate is developed. It is used for elucidating the errors of the WLF method which is implicitly based on the tank model where the horizontal flow in the saturated zone is ignored. Simulations show that the recharge estimated by the WLF method is underestimated for the observation well near the discharge boundary. This is due to the fact that the hydraulic stress resulting from the recharge is rapidly dissipating by the horizontal flow near the discharge boundary Simulations also reveal that the recharge was significantly underestimated with increase in the hydraulic conductivity and the recharge duration, and decrease in the specific yield.

• 한국수자원학회논문집
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• 제38권7호
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• pp.517-526
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• 2005

현재 우리나라에서 주로 사용되는 지하수 함양량 추정방법은 지하수 감수곡선에 의한 기저유출분리법과 관측공의 자료를 이용한 지하수위 변동법으로 대별된다. 기저유출분리법은 연단위기반의 집중형 개념의 접근법을 사용하며, 지하수위변동곡선해석법은 유역단위의 물수지 개념보다는 국지적인 지하수 관측정의 변화에 주로 의존하고 있다. 한편 지하수 함양량은 기후조건, 토지이용, 관개와 수리지질학적 비균질성에 의해 현저한 시공간적 변동성을 나타내고 있어서 위의 두 가지 방법으로는 이같은 특성을 고려하는데 여러 가지 한계를 보인다. 이에 본 연구에서는 준분포형 강우-유출모형인 SWAT모형을 이용하여 공간적변동성을 고려한 일단위 함양량 산정기법을 제시하였다. 이 방법을 이용하면 기존의 유역 대표 함양량 대신 각 소유역의 비균질한 특성을 반영한 함양량의 분포를 산정할 수 있다. 산정된 일단위 함양량은 기후조건 토지이용 및 수리지질학적 비균질성과 토양층에서의 지체등 물리적인 거동까지 반영된 것이어서 기존의 간접적 추정방식에 의한 연단위 함양률을 크게 개선할 수 있을 것으로 기대된다.

• 지질공학
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• 제30권3호
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• pp.269-278
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• 2020

본 연구에서는 현장 주입 시험 및 3차원 수치모델을 이용하여 상류 소분지에서의 수직정을 이용한 지하수 인공함양 효과를 예비 평가하였다. 현장 주입 시험의 주입량, 지하수위 및 입도 분석 자료에 의한 수리전도도 등을 이용하여 모델의 공당 주입량을 20, 37.5, 60, 75 ㎥/day로 설정하였으며, 주입 간격에 따른 총 28개의 경우에 대하여 MODFLOW를 활용한 수치모델을 실시하여 지하수위 및 물수지 변화를 분석하였다. 주입 후 주변 관측정에서의 지하수위 상승이 공당 주입량과 비례적인 선형 관계를 보이진 않았으며, 주입 간격이 길어지면 누적 효과가 감소하여 최대 수위상승 시기가 짧아지는 것으로 나타났다. 또한 4가지 경우의 공당 주입량을 매일 연속으로 주입하여 총량 1,200 ㎥을 주입할 경우, 주입량 대비 36.5~65.3%의 함양 효과가 나타나는 것으로 분석되었다. 그러나 장기간의 가뭄에 대응하고 보다 지속적인 양수를 위해서는 차수벽 등 지하수 저류시설을 병행한다면 보다 효과적일 것으로 보이며, 추후 주입 시설의 최적화 및 함양-취수의 시나리오 확보를 통하여 안정적인 인공함양 시스템 구축이 가능할 것이다.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2006년도 총회 및 춘계학술발표회
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• pp.293-297
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• 2006

Submarine groundwater discharge (SGD) and the interface between seawater and freshwater in an unconfined coastal aquifer was evaluated by numerical modeling. A two-dimensional vertical cross section of the aquifer was constructed. Coupled flow and salinity transport modeling were peformed by using a numerical code FEFLOW In this study, we investigated the changes in groundwater flow and salinity transport in coastal aquifer with hydraulic condition such as the magnitude of recharge flux, hydraulic conductivity. Especially, transient simulation considering tidal effect and seasonal change of recharge rate was simulated to compare the difference between quasi-steady state and transient state. Results show that SGD flux is in proportion to the recharge rate and hydraulic conductivity, and the interface between the seawater and the freshwater shows somewhat retreat toward the seaside as recharge flux increases. Considered tidal effect, SGD flux and flow directions are affected by continuous change of the sea level and the interface shows more dispersed pattern affected by velocity variation. The cases which represent variable daily recharge rate instead of annual average value also shows remarkably different result from the quasi-steady case, implying the importance of transient state simulation.

• 한국환경과학회지
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• 제17권2호
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• pp.257-267
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• 2008

Groundwater recharge characteristics in a fractured granite area, Mt. Geumjeong, Korea. was interpreted using bedrock groundwater and wet-land water data. Time series analysis using autocorreclation, cross-correlation and spectral density was conducted for characterizing water level variation and recharge rate in low water and high water seasons. Autocorrelation analysis using water levels resulted in short delay time with weak linearity and memory. Cross-correlation function from cross-correlation analysis was lower in the low water season than the high water season for the bedrock groundwater. The result of water level decline analysis identified groundwater recharge rate of about 11% in the study area.

• 한국지하수토양환경학회지:지하수토양환경
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• 제16권6호
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• pp.34-45
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• 2011

For the Hancheon drainage area in Jeju island, a groundwater flow model using Visual MODFLOW was developed to simulate artificial recharge through injection wells installed in the Hancheon reservoir. The model was used to analyze changes of the groundwater level and the water budget due to the artificial recharge. The model assumed that $2{\times}10^6m^3$ of storm water would recharge annually through the injection wells during the rainy season. The transient simulation results showed that the water level rose by 39.6 m at the nearest monitoring well and by 0.26 m at the well located 7 km downstream from the injection wells demonstrating a large extent of the affected area by the artificial recharge. It also shown that, at the time when the recharge ended in the 5th year, the water level increased by 81 m at the artificial reservoir and the radius of influence was about 2.1 km downstream toward the coast. The residence time of recharged groundwater was estimated to be no less than 5 years. The model also illustrated that 15 years of artificial recharge could increase the average linear velocity of groundwater up to 1540 m/yr, which showed 100 m/yr higher than before. Increase of groundwater storage due to artificial recharge was calculated to be $2.4{\times}10^6$ and $4.3{\times}10^6m^3$ at the end of the 5th and 10th years of artificial recharge, respectively. The rate of storage increase was gradually diminished afterwards, and storage increase of $5.0{\times}10^6m^3$ was retained after 15 years of artificial recharge. Conclusively, the artificial recharge system could augment $5.0{\times}10^6m^3$ of additional groundwater resources in the Hancheon area.