• 한국지하수토양환경학회지:지하수토양환경
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• 제13권1호
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• pp.67-76
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• 2008

본 연구에서는 지하수위 변동모델과 비포화대 함수모델을 적용한 지하수 함양율 산정 기법을 제안하였다. 기법의 적용성을 살펴보기 위하여 연구지역인 국내 4개 국가지하수 관측소를 선정하였으며 1996년부터 2005년에 이르는 국가 지하수 관측망(포항 연일, 기북, 순천 외서, 홍천 홍천) 수위자료와 포항, 순천, 홍천의 기상청 강우자료가 이용되었다. 각 관측소 주변 토양형에 따른 지하수 함양율은 홍천 관측소가 최소 0.5%에서 최대 61.4%, 포항 연일 관측소는 1.1%에서 27.4%, 포항 기북 관측소는 5.1%에서 41.4%, 및 순천 외서 관측소는 1.1%에서 8.3%의 분포를 보였다. 본 연구에서 이용된 지하수위 변동예측 모델은 지하수위 변동이 강우에 의해서만 발생하는 것으로 가정하였으며 향후 보다 정확한 지하수위 예측을 위해서 지하수 채수나 증발산의 영향을 추가 고려할 필요가 있을 것이라 판단된다. 또한 제안된 기법의 보다 넓은 범위의 적용을 위해서는 비포화 암반의 함수 모델을 도입할 필요가 있을 것이라 판단된다. 현재 본 연구를 공간적으로 확장하여 지역화 하기 위한 연구가 진행 중이다. 본 연구에서 제안하는 지하수 함양율 산정 기법은 가정을 최소화함으로써 방법론적으로 합리적이며 실제 지하수 시스템을 잘 반영하는 과학적인 모델로 기존 지하수 함양율 산정 기법을 충분히 대체할 수 있을 것이라 판단된다.

• 대한토목학회논문집
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• 제33권6호
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• pp.2277-2284
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• 2013

본 연구에서 개발하고자 하는 지하수위 변동 해석모델은 지하수의 흐름과 관련된 반응계수 및 함양형태와 관련된 비산출율을 매개변수로 하여 부정류상태에서의 지하수위 변동특성을 해석한다. 모델의 시험적용을 위해 제주도 한천지역의 JD 용담1과 JW 공항지점의 5년(2006-2010)간의 지하수위 관측자료를 이용하였다. 매개변수 산정결과, JD 용담1지점에서는 비산출율 0.023, 반응계수 0.039로 추정되었고, JW 공항지점에서는 각각 0.009와 0.028로 추정되었다. 본 연구에서 개발한 모델을 이용하면, 지하수위에 의한 함양량 및 포화대에서의 매개변수를 추정할 수 있어 수문모형의 매개변수 및 비포화대에서의 침루특성을 확인하는 수단으로 활용되기를 기대한다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제16권3호
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• pp.17-27
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• 2011

Recently, a physically based model of water-table fluctuation due to precipitation is developed based on aquifer water balance model. In the model, it was assumed that the water infiltration into ground surface is advection dominant and immediately reaches to water-table. The assumption may be suited for the sites where the water-table is shallow and/or the permeability of the unsaturated zone is high. However, there are more cases where the model is not directly applicable due to thick and low permeable unsaturated zone. For the low permeability unsaturated zone, the pattern of water flux passing through unsaturated zone is diffusive as well as advective. In this study, to improve the previously developed water-table fluctuation model, we combined the delayed drainage model, which has long been used in well hydraulics, to the water-table fluctuation model. To test the validity of the development, we apply the developed model to 5 different domestic sites. The model parameters are calibrated based on the groundwater hydrograph and the precipitation time series, and the correlation analyses among the parameters are pursued. The overall analyses on the delineated model parameters indicate that the delayed drainage parameters or delay index used in the developed model are able to reveal drainage information in the unsaturated zones.

• 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.

• 한국환경과학회지
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• 제26권10호
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• pp.1135-1146
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• 2017

At riverbank filtration sites, groundwater levels of alluvial aquifers near rivers are sensitive to variation in river discharge and pumping quantities. In this study, the groundwater level fluctuation, pumping quantity, and streamflow rate at the site of a riverbank filtration plant, which produces drinking water, in the lower Nakdong River basin, South Korea were interrelated. The relationship between drawdown ratio and river discharge was very strong with a correlation coefficient of 0.96, showing a greater drawdown ratio in the wet season than in the dry season. Autocorrelation and cross-correlation were carried out to characterize groundwater level fluctuation. Autoregressive model analysis of groundwater water level fluctuation led to efficient estimation and prediction of pumping for riverbank filtration in relation to river discharge rates, using simple inputs of river discharge and pumping data, without the need for numerical models that require data regarding several aquifer properties and hydrologic parameters.

• 한국지하수토양환경학회지:지하수토양환경
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• 제18권5호
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• pp.65-76
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• 2013

The water-table fluctuation (WTF) method has been often used for estimating groundwater recharge by analysis of waterlevel measurements in observation wells. An important assumption inherent in the method is that the water level rise is solely caused by precipitation recharge. For the observation wells located near a stream, however, the water-level can be highly affected by the stream level fluctuations as well as precipitation recharge. Therefore, in applying the WTF method, there should be consideration regarding the effect of stream-aquifer interactions. Analysis of water-level hydrographs from the National Groundwater Monitoring Wells of Korea showed that they could be classified into three different types depending on their responses to either precipitation recharge or stream level fluctuations. A simple groundwater flow model was used to analyze the errors of the WTF method, which were associated with stream-aquifer interactions. Not surprisingly, the model showed that the WTF method could greatly overestimate recharge, when it was used for the observation wells of which the water-level was affected by streams. Therefore, in Korea, where most groundwater hydrographs are acquired from wells nearby a stream, more caution is demanded in applying the WTF method.

• Geomechanics and Engineering
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• 제18권6호
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• pp.575-584
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• 2019

The groundwater level (GWL) is an important subsoil condition for the design of foundation. GWL tends to fluctuate often with seasonal variation, which may cause unexpected, additional settlements with some reductions in the safety margin of foundation. In this study, the effects of fluctuating GWL on the load carrying and settlement behavior of footing were investigated and quantified. A series of model load tests were conducted for various GWL and soil conditions using a hydraulically-controlled chamber system. Changes in load level and rising and falling GWL fluctuation cycle were considered in the tests. Settlements during GWL rise were greater than those during GWL fall. The depth of the GWL influence zone ($\underline{d}_{w,inf}$) varied in the range of 0.3 to 1.5 times footing width and became shallower as GWL continued to fluctuate. Design equations for estimating GWL-induced settlements for footings were proposed. The GWL fluctuation cycle, load level and soil density were considered in the proposed method. Changes in settlement and factor of safety with GWL fluctuation were discussed.

• 대한토목학회논문집
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• 제33권6호
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• pp.2285-2291
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• 2013

본 연구에서는 Kim et al. (2013)이 개발한 부정류상태에서의 지하수위 변동 해석모델을 이용하여 단위시간별 함양량을 산정하였다. 지하수위 변동 해석모델은 지하수의 흐름과 관련된 반응계수와 함양에 관련된 비산출율을 매개변수로 이용한다. 해석모델의 적용을 위해 제주도 한천지역의 관측정 중 강우에 대한 반응이 양호한 JW 공항과 JD 용담1지점에 대한 5년(2006-2010)간의 지하수위 관측자료를 이용하였다. 지하수위 해석모델은 국지적인 규모에서의 단위시간별(일별) 함양량 산정이 가능하며 지하수위 자료와 비교한 결과, 함양량과 매개변수가 지하수위를 잘 반영하고 있었다. 함양량 산정결과 JD 용담1 지점은 520.4~904.0mm (32.7~61.8%), JW 공항지점은 447.4~633.4mm (24.0~45.1%)로 나타났다. 개발된 해석모델은 지하수위 자료를 이용하여 매개변수를 추정과 단위시간별 함양량을 산정하는 방안으로 활용되기를 기대된다.

• 대한토목학회논문집
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• 제34권5호
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• pp.1409-1420
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• 2014

지하수위 변동 해석모델을 이용하여 제주지역의 대수층 수리지질 매개변수인 반응계수와 배수가능공극을 추정하고 고도에 따른 분포특성 및 민감도분석을 실시하였다. 대수층 매질의 특성치인 배수가능공극은 고도에 대해 일정한 경향성을 보이지 않으며 지하수의 흐름 특성치인 반응계수는 고도가 높아질수록 낮아지는 뚜렷한 경향성을 보였다. 매개변수들에 대한 민감도를 알아보기 위해 매개변수의 평균 및 관계식을 이용하여 추정함양량을 비교한 결과, 전 유역(강정천, 외도천, 천미천, 한천)에 대한 매개변수 관계식을 적용하여도 미계측 유역내 매개변수의 추정이 가능할 것으로 판단된다. 따라서 본 연구의 결과를 통해 대표적인 수리지질 매개변수의 분포특성을 파악하여 미계측지역에서 매개변수를 추정함으로써 지하수모델링의 기초자료로도 활용 가능할 것으로 기대한다.

• 한국농공학회논문집
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• 제65권2호
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• pp.1-11
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• 2023

This study analyzed the impact of greenhouse cultivation area and groundwater level changes due to the water curtain cultivation in the greenhouse complexes. The groundwater observation data in the Miryang study area were used and classified into greenhouse and field cultivation areas to compare the groundwater impact of water curtain cultivation in the greenhouse complex. We identified the characteristics of the groundwater time series data by the terrain of the study area and selected the optimal model through time series analysis. We analyzed the time series data for each terrain's two representative groundwater observation wells. The Seasonal ARIMA model was chosen as the optimal model for riverside well, and for plain and mountain well, the ARIMA model and Seasonal ARIMA model were selected as the optimal model. A suitable prediction model is not limited to one model due to a change in a groundwater level fluctuation pattern caused by a surrounding environment change but may change over time. Therefore, it is necessary to periodically check and revise the optimal model rather than continuously applying one selected ARIMA model. Groundwater forecasting results through time series analysis can be used for sustainable groundwater resource management.