• Title/Summary/Keyword: Groundwater well

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Investigation on Tunneling and Groundwater Interaction Using a 3D Stress-pore Pressure Coupled Analysis (응력-간극수압 3차원 연계해석을 통한 터널굴착과 지하수의 상호작용 고찰)

  • 유충식
    • Journal of the Korean Geotechnical Society
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    • v.20 no.3
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    • pp.33-46
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    • 2004
  • This paper presents the effect of groundwater on tunnel excavation. Fundamental issues in tunneling under high groundwater table are discussed and the effect of groundwater on tunnel excavation was examined using a 3D stress-pore pressure coupled finite-element analysis. Based on the results the interaction mechanism between the tunnelling and groundwater is identified for cases having different lining permeabilities. Examined items include pore pressures around lining and lining stresses. Face deformation behavior as well as ground surface movement patterns was also examined. Besides, the effect of grouting pattern was investigated. The results indicated that the effect of groundwater on tunnel excavation increases lining stresses as well as ground movements, and that the tunnel excavation and groundwater interaction can only be captured through a fully coupled analysis. Implementations of the findings from this study are discussed in great detail.

Application and Assesment of Regrouting Method for Improperly Constructed Wells in Jeju Island (제주도의 오염 방지 시공이 부실한 지하수 관정에 대한 구간 차폐 공법의 적용과 평가)

  • Kim, Mijin;Kang, BongRae;Cho, Heuy Nam;Choi, Sung Ouk;Yang, Won-Seok;Park, Wonbae
    • Journal of Soil and Groundwater Environment
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    • v.25 no.3
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    • pp.43-51
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    • 2020
  • About 90% of groundwater wells in Jeju Island are reported to be under the threat of contamination by infiltration of the surface pollutants. Most of those wells have improperly grouted annulus which is an empty space between the well and the inner casing. As a remedy to this problem, some of the wells were re-grouted by filling the annulus with cement without lifting an inner casing. In order to evaluate whether this method is appropriate for the geological structure of Jeju Island, two wells (W1 and W2) were selected and this method was applied. The water holding capacity did not decrease while the nitrate levels decreased from 16.8 and 20.2 to 6.8 and 13.8 mg/L in W1 and W2, respectively. The higher nitrate level in W2 is deemed to be influenced by the livestock farms located in the upper area of the well. In addition, transmissivity of the vedose zone was higher in W2 than W1, potentially facilitating the transport of nitrate to the groundwater. The overall result of this study suggests re-grouting of wells for the purpose of protecting water quality of goundwater should take into account geological structure of vadose zone as well as appropriate source control of the contaminants.

지하수 폐공 원상복구 개선방안

  • Jeong, Ha-Ik;Lim, Jong-Jin;Yoo, Jun;Kim, Sang-Geun;Oh, In-Gyu;Hong, Seung-Seo
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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    • 2003.09a
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    • pp.244-248
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    • 2003
  • Unused well and improperly abandoned wells are a significant threat to groundwater quality. If abandoned wells is not properly filled with material, it can directly channel to flow contaminated and surface water into subsurface and groundwater. The abandonment process is over viewed and the method of filling with impermeable and permeable material is presented for the purpose of proper well abandonment work.

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Numerical Analysis of Horizontal Collector Well in Riverbank Filtration (수평 방사형 집수정 활용 강변여과 취수 수치 분석)

  • Kim, Hyoung-Soo;Jeong, Jae-Hoon
    • Journal of Soil and Groundwater Environment
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    • v.14 no.1
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    • pp.1-10
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    • 2009
  • Groundwater flow due to intake of horizontal collector well in riverbank filtration site was analyzed by use of numerical groundwater modeling program (FEFLOW 5.1). Drawdowns of groundwater table nearby collector well were evaluated according to variations of several conditions; pumping rate, thickness of aquifer, offset distance from well to shore line of stream, conductance of streambed. It is observed that the drawdowns of groundwater table are clearly changed according to the variations of these conditions. The results of sensitive analysis shows that the thickness of alluvial aquifer and the offset distance are more sensitive than the conductance of streambed in evaluation of drawdown. This result implies that hydrogeological conditions, as like thickness of aquifer and its distribution in the site are important factors in site selection and evaluating the availability of riverbank filtration intake using horizontal collector well system. It is also revealed that numerical modeling using FEFLOW with 1-D discrete element feature can give efficient quantitative evaluation of horizontal collector well and estimation of availability of riverbank filtration site.

A Comparison of Estimated Groundwater Consumption Using Existing Formulae with Actual Pumped Volumes in the Haean Basin, Korea (양구해안분지에서 기존 농업용수 이용량 산정식에 따른 양수량과 실측 양수량 비교)

  • Ryu, Han-Sun;Jeon, Woo-Hyun;Kwon, Kideok;Lee, Jin-Yong
    • Journal of Soil and Groundwater Environment
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    • v.22 no.4
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    • pp.1-8
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    • 2017
  • Efficient groundwater management requires accurate information about the water volume used. The pumped volume of groundwater can be indirectly estimated using empirical formulae based on electric power consumption. The purpose of this study is to test the accuracy of this indirect method. The Haean basin in Gangwon is located in a rural area, where majority of the groundwater extracted is used for irrigation. The pumped volume of groundwater indirectly estimated from electricity usage using these empirical formulae was compared with the actual pumped volume determined by conducting experiments on April 29 and May 19, 2017. The field survey collected data on electricity usage, pumped volume, and groundwater levels. Based on this measured data, correlations were calculated between electricity usage and pumping volume, as well as groundwater level and pumping rate. The results show that electricity usage and pumped volume measured for both wells (YHE1 and YHE2) are highly correlated (r=0.99, p<0.001). However, for YHE1, notably, the correlation between the groundwater level and pumping rate was not significant, and only some correlations were identified for these variables for the YHE2 test well. The average error with respect to the estimation of the actual pumped volume from the existing formula (1) and formulae (2) and (3) are +399% and -88%, respectively. To reduce these errors, these formulae need to consider other factors affecting the pumped volume.

A Modification of SWMM for a Groundwater Pumping Simulation (지하수 양수 모의를 위한 SWMM의 수정)

  • Lee, Sang-Ho;Lee, Jung-Min
    • Journal of Korean Society on Water Environment
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    • v.23 no.5
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    • pp.628-635
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    • 2007
  • As the hydrologic cycle is transformed by the expansion of impermeable area as a result of the urbanization, the function of an ecosystem is deteriorated by the transformed hydrologic cycle. In this study, a SWMM code was modified to have a groundwater pumping option about rivers-aquifer interaction to be possible. The modified SWMM was applied to continuous simulations of urban runoff from Hakuicheon watershed and it was used to analyse the effect of a groundwater pumping. The modified SWMM overcame the limitation of the ground subroutine that it only simulate groundwater inflow from ground to rivers. The result of continuous simulation of groundwater pumping is that surface runoff, groundwater runoff and groundwater level are well simulated, and Modified SWMM expressed groundwater runoff by negative number (-) when groundwater level is less than river stage.

A study of the pollution of ground water in the basin of the river Baem Nae Chun, Sorae-Myun, Shihoong-gon, Kyonggi-Do, Korea (경기도 시흥군 소래면 뱀내하천 유역의 지하수 오염에 관한 연구)

  • 김윤종;정봉일
    • Water for future
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    • v.6 no.2
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    • pp.19-29
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    • 1973
  • The progressive contamination of water resulted from man's activity and the use of fertilizers is not restricted only to surface water, but also the shallow groundwater is affected. This type of groundwater contamination is mainly restricted to areas composed of permeable, nonconsolidated sediments forming a shallow aquifer. The chloride and the sulfate resulted from man's activity and the use of fertilizers were measured to study the variations of the groundwater contamination. In general, (1) When water level rises, the rate of groundwater contamination becomes less and when water level declines, the rate of contamination is increased. (2) The highly contaminated season is the early-summer and the less contaminated season is the winter or after rainy season. (3) The groundwater in weathering zone without covering layer. (4) The degree of contamination of wells is increased with the increase of well depth and lowing the water table, because of increasing contaminated water from enlargement of the area of influence of the well.

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Sensitivity Analysis of Artificial Recharge in Consideration of Hydrogeologic Characteristics of Facility Agricultural Complex in Korea : Hydraulic Conductivity and Separation Distance from Injection Well to Pumping Well (국내 시설농업단지의 수리지질 특성을 고려한 인공함양 민감도 분석 : 수리전도도 및 주입정과 양수정의 이격거리)

  • Choi, Jung Chan;Kang, Dong-hwan
    • Journal of Environmental Science International
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    • v.28 no.9
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    • pp.737-749
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    • 2019
  • In this study, the sensitivity analysis of hydraulic conductivity and separation distance (distance between injection well and pumping well) was analyzed by establishing a conceptual model considering the hydrogeologic characteristics of facility agricultural complex in Korea. In the conceptual model, natural characteristics (topography and geology, precipitation, hydraulic conductivity, etc.) and artificial characteristics (separation distance from injection well to pumping well, injection rate and pumping rate, etc.) is entered, and sensitivity analysis was performed 12 scenarios using a combination of hydraulic conductivity ($10^{-1}cm/sec$, $10^{-2}cm/sec$, $10^{-3}cm/sec$, $10^{-4}cm/sec$) and separation distance (10 m, 50 m, 100 m). Groundwater drawdown at the monitoring well was increased as the hydraulic conductivity decreased and the separation distance increased. From the regression analysis of groundwater drawdown as a hydraulic conductivity at the same separation distance, it was found that the groundwater level fluctuation of artificial recharge aquifer was dominantly influenced by hydraulic conductivity. In the condition that the hydraulic conductivity of artificial recharge aquifer was $10^{-2}cm/sec$ or more, the radius of influence of groundwater level was within 20 m, but In the condition that the hydraulic conductivity is $10^{-3}cm/sec$ or less, it is confirmed that the radius of influence of groundwater increases sharply as the separation distance increases.

Determination of the Groundwater Yield of horizontal wells using an artificial neural network model incorporating riverside groundwater level data (배후지 지하수위를 고려한 인공신경망 기반의 수평정별 취수량 결정 기법)

  • Kim, Gyoo-Bum;Oh, Dong-Hwan
    • The Journal of Engineering Geology
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    • v.28 no.4
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    • pp.583-592
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    • 2018
  • Recently, concern has arisen regarding the lowering of groundwater levels in the hinterland caused by the development of high-capacity radial collector wells in riverbank filtration areas. In this study, groundwater levels are estimated using Modflow software in relation to the water volume pumped by the radial collector well in Anseongcheon Stream. Using the water volume data, an artificial neural network (ANN) model is developed to determine the amount of water that can be withdrawn while minimizing the reduction of groundwater level. We estimate that increasing the pumping rate of the horizontal well HW-6, which is drilled parallel to the stream direction, is necessary to minimize the reduction of groundwater levels in wells OW-7 and OB-11. We also note that the number of input data and the classification of training and test data affect the results of the ANN model. This type of approach, which supplements ANN modeling with observed data, should contribute to the future groundwater management of hinterland areas.

Predicting the Impact of Subsurface heterogeneous Hydraulic Conductivity on the Stochastic Behavior of Well Draw down in a Confined Aquifer Using Artificial Neural Networks

  • Abdin Alaa El-Din;Abdeen Mostafa A. M.
    • Journal of Mechanical Science and Technology
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    • v.19 no.8
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    • pp.1582-1596
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    • 2005
  • Groundwater flow and behavior have to be investigated based on heterogeneous subsurface formation since the homogeneity assumption of this formation is not valid. Over the past twenty years, stochastic approach and Monte Carlo technique have been utilized very efficiently to understand the groundwater flow behavior. However, these techniques require lots of computational and numerical efforts according to the various researchers' comments. Therefore, utilizing new techniques with much less computational efforts such as Artificial Neural Network (ANN) in the prediction of the stochastic behavior for the groundwater based on heterogeneous subsurface formation is highly appreciated. The current paper introduces the ANN technique to investigate and predict the stochastic behavior of a well draw down in a confined aquifer based on subsurface heterogeneous hydraulic conductivity. Several ANN models are developed in this research to predict the unsteady two dimensional well draw down and its stochastic characteristics in a confined aquifer. The results of this study showed that ANN method with less computational efforts was very efficiently capable of simulating and predicting the stochastic behavior of the well draw down resulted from the continuous constant pumping in the middle of a confined aquifer with subsurface heterogeneous hydraulic conductivity.