• Title/Summary/Keyword: shallow groundwater

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환경물리탐사 기법을 이용한 유류오염 주유소 부지 특성 조사

  • Kim Chang-Ryeol;Go Gyeong-Seok;Kim Jeong-Ho;Park Sam-Gyu;Son Jeong-Sul;Jeong Ji-Min
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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    • 2005.04a
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    • pp.429-432
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    • 2005
  • Geophysical investigations, as a non-invasive method, were conducted at the former gas station site contaminated with fuel hydrocarbons. GPR (Ground Penetrating Radar) survey was performed to locate buried objects such as USTs (Underground Storage Tanks) and fuel pipes which might serve as a origin of the site contamination. Additional GPR investigation and a resistivity survey were conducted to map water table and to characterize shallow geologic structures of the site. The results of the study have shown that seven USTs including one unknown UST and buried fuel pipes are present, and that the groundwater elevation varies with topography from approximately 1.5 to 3m below the surface and the water table is located in the residual soils above the bedrock in the site. The results also show that the geophysical methods can be a very useful tool for the characterization of the contaminated site.

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A numerical analysis of precipitation recharge in the region of monsoon climates using an infiltration model

  • Koo, Min-Ho;Kim, Yongje
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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    • 2003.04a
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    • pp.163-167
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    • 2003
  • Based on the transient finite difference solution of Richards' equation, an infiltration model is developed to analyze temporal variation of precipitation recharge in the region of monsoon climates. Simulation results obtained by using time series data of 20-year daily precipitation and pan evaporation indicate that a linear relationship between the annual precipitation and the annual recharge holds for the soils under the monsoon climates with varying degrees of the correlation coefficient depending on the soil types. A sensitivity analysis reveals that the water table depth has little effects on the recharge for the sandy soil, whereas, for the loamy and silty soils, rise of the water table at shallow depths causes increase of evaporation by approximately 100㎜/yr and a corresponding decrease in recharge. A series of simulations for two-layered soils illustrate that the amount of recharge is dominantly determined by the soil properties of the upper layer, although the temporal variation of recharge is affected by both layers.

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Case Study: Groundwater Recharge Hydrograph in Pyeongchang River (평창강 지하수 함양곡선 연구)

  • Kwak, Jaewon
    • Journal of Wetlands Research
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    • v.23 no.2
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    • pp.173-182
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    • 2021
  • It is important to extract and assess low-flow recession characteristics for water resources management in the upper reaches of a stream. It is difficult to express the groundwater flow recession characteristics for streamflow synthetically. The linear recession model has been widely used by baseflow recession analysis for reason of simplicity and convenience, but recent studies show that nonlinear recession models fit well, and the relationship between the reservoir storage of shallow unconfined aquifers and the groundwater discharge was to be identified as nonlinear in the literature based on the analysis of numerous streamflow recession curves. The objective of the study is to decode these nonlinear characteristics, including evaporation loss, storage, and recharge of groundwater using streamflow. By analyzing the observed time series of streamflow from the study area, which is the Pyeongchang River basin in Korea, the main components of the underlying groundwater balance, namely, discharge, evaporation loss, storage, and recharge, can be identified and quantified. As a result of the study, depletion of groundwater by evapotranspiration losses through the water uptake of tree roots was found to bias the recession curves and the estimated reservoir parameters. The seasonality of both rainfall and potential evaporation, analysis of the recession curves, stratified according to time of the year, allowed the quantification of evapotranspiration loss as a function of a calendar month and stored groundwater storage.

Groundwater Quality and Contamination in Dukpyung area (충북 괴산군 덕평리 일대의 지하수 수질과 오염)

  • 김형돈;우남칠;최미정
    • Journal of the Korean Society of Groundwater Environment
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    • v.5 no.3
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    • pp.141-147
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    • 1998
  • This study was initiated to identify the general groundwater quality and the effects of heavy-metal enrichments in the black shales and coal materials in Dukpyung area. Groundwater quality could be divided into three groups based on the major weathering processes in the groundwater system; Group I of carbonate weathering, Group II of silicate weathering with the probable effects of acidic mine drainage, and Group III of silicate weathering with relatively high concentrations of chloride components in anions. Metal contamination of groundwater was not observed. Locally, however, acidic mine drainage appeared to be produced and recharged into the groundwater system. In addition, contamination by NO$_3$-N ranged 2 to 3 times higher than the drinking water standards, probably due to infiltration of domestic sewage and/or fertilizers into the shallow aquifer.

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A Study on Significant Parameters for Efficient Design of Open-loop Groundwater Heat Pump (GWHP) Systems (개방형 지열시스템의 효율적 설계를 위한 영향인자에 대한 연구)

  • Park, Byeong-Hak;Joun, Won-Tak;Lee, Bo-Hyun;Lee, Kang-Kun
    • Journal of Soil and Groundwater Environment
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    • v.20 no.4
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    • pp.41-50
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    • 2015
  • Open-loop groundwater heat pump (GWHP) system generally has benefits such as a higher coefficient of performance (COP), lower initial cost, and flexible system size. The hydrogeological conditions in Korea have the potential to facilitate the use of the GWHP system because a large number of monitoring wells show stable groundwater temperatures, shallow water levels, and high well yields. However, few studies have been performed in Korea regarding the GWHP system and the most studies among them dealt with Standing Column Well (SCW). Because the properties of the aquifer have an influence on designing open-loop systems, it is necessary to perform studies on various hydrogeological settings. In this study, the hydrogeological and thermal properties were estimated through various tests in the riverside alluvial layer where a GWHP system was installed. Under different groundwater flow velocities and pumping and injection rates, a sensitivity analysis was performed to evaluate the effect of such properties on the design of open-loop systems. The results showed that hydraulic conductivity and thermal dispersivity of the aquifer are the most sensitive parameters in terms of performance and environmental aspects, and sensitivities of the properties depend on conditions.

Effect of Rainfall Patterns on the Response of Water Pressure and Slope Stability Within a Small Catchment: A Case Study in Jinbu-Myeon, South Korea

  • Viet, Tran The;Lee, Giha;Oh, Sewook;Kim, Minseok
    • Journal of the Korean GEO-environmental Society
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    • v.17 no.12
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    • pp.5-16
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    • 2016
  • This study aims to assess the influence of rainfall patterns on shallow landslides initiation. Doing so, five typical rainfall patterns with the same cumulative amount and intensity components comprising Advanced (A1 and A2), Centralized (C), and Delayed (D1 and D2) were designed based on a historical rainstorm event in Jinbu. Mt area. Those patterns were incorporated as the hydrological conditions into the Transient Rainfall Infiltration and Grid-based Regional Slope-stability Model (TRIGRS) to assess their influences on groundwater pressure and changes in the stability of the slope. The results revealed that not only the cumulative rainfall thresholds necessary to initiate landslides, but also the rate at which the factor of safety decreases and the time required to reach the critical state, are governed by rainfall patterns. The sooner the peak rainfall intensity, the smaller the cumulative rainfall threshold, and the shorter the time until landslide occurrence. Left-skewed patterns were found to have a greater effect on landslide initiation. Specifically, among five rainfalls, pattern (A1) produced the most critical state. The severity of response was followed by patterns A2, C, D1, and D2. Our conclusion is that rainfall patterns have a significant effect on the cumulative rainfall threshold, the build-up of groundwater pressure, and the occurrence of shallow landslides.

Hydrogeochemical Assessment of Groundwater Quality Security in the Collection Conduit Area, Naeseong-Cheon (내성천 집수매거의 수질 확보를 위한 충적층 지하수의 수질 특성 평가)

  • Shin, Kyung-Hee;Cha, Eun-Jee;Son, Yeong-Cheol;Lee, Seung-Hyun;Kim, Gyoo-Bum
    • The Journal of Engineering Geology
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    • v.23 no.1
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    • pp.1-17
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    • 2013
  • It is sometimes necessary to change the location of the collection conduit, which is constructed in shallow sediments in a stream, if the concentrations of $Fe^{2+}$ and $Mn^{2+}$ become too high for water treatment. A total of nine wells, including four shallow wells with a depth of 3 m and five deeper wells with a depth of 6 m, were installed in the study area at Naeseong-cheon in Yecheon-gun. The change in hydrogeochemical features of groundwater and the concentrations of $Fe^{2+}$ and $Mn^{2+}$ were examined at the wells during 5 hours of pumping. As pumping was performed, the velocity of groundwater flow was increased around the pumping well and aeration conditions were developed to precipitate iron and manganese oxides in an oxidizing environment. In addition, the concentrations of $Ca^{2+}$ and $Cl^-$ at the pumping well were increased following the mixing of surface water and groundwater. It is suggested that the center region of the stream would be more suitable for a new collection conduit, considering the concentrations of $Fe^{2+}$ and $Mn^{2+}$ in groundwater and their reducing effect during pumping. The installation of a collection conduit based on field tests performed to ensure water quality enables a reduction in the construction and management costs at water treatment facilities.

Groundwater Quality in the Shallow Aquifer at the Plastic Film Houses Area near Livestock Area in Kyongan River Basin (경안천유역내 축산단지 인근 시설원예지역의 천층지하수 수질특성)

  • 김진호;문광현;안승구
    • Journal of Korea Soil Environment Society
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    • v.5 no.3
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    • pp.77-85
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    • 2001
  • This study was carried out to show the groundwater quality in the shallow aquifer at the plastic film houses area near livestock areas in Kyong=n river. The study was conducted at 31 sites in Pogok Myon. Yongin City, Kyonggi Province on March, June and August in 1998, Medium value of CO $D_{cr}$ by survey months was as follows ; June(8.0mg/L) > April(4.4mg/L) > August(3.2mg/L). And the value of $NH_3$-N showed same tendency ; June (0.21mg/L) > April(0.08mg/L) > August (0.04mg/L). In case of nitrate- nitrogen, the changes by survey months were shown similar. But 28% of survey sites exceeded to agricultural groundwater quality reference level(20mg/L). And sulfur concentrations at some survey sites exceeded the reference level(50mg/L). But the other items of water quality were shown to suitable level for agriculture. The result showed that groundwater quality management should be taken for agricultural using at the livestock and plastic film house areas.

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Effect of groundwater fluctuation on load carrying performance of shallow foundation

  • Park, Donggyu;Kim, Incheol;Kim, Garam;Lee, Junhwan
    • Geomechanics and Engineering
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    • v.18 no.6
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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.

Water Quality Changes in Wastewater Effluent from the Unsaturated and Saturated Soil Aquifer Treatment(SAT) Columns Simulating Shallow Aquifer (얕은 불포화 및 포화 대수층을 모사한 SAT 토양칼럼에서의 하수처리장 방류수 처리 수질 변화)

  • Cha Woo-Suk;Kim Jung-Woo;Choi Hee-Chul;Won Jong-Ho;Kim In-Soo;Cho Jae-Weon
    • Journal of Soil and Groundwater Environment
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    • v.10 no.5
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    • pp.18-24
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    • 2005
  • Water quality changes of wastewater effluent in the shallow aquifier condition was investigated using laboratory unsaturated and saturated SAT columns for over five months. Average DOC removal was 31.9% in the unsaturated SAT column whereas no removal occurred in the saturated SAT column. Under the shallow aquifer condition, nitrification was not completed in the unsaturated SAT column, releasing residual ammonium nitrogen into the saturated SAT column. Short retention time (one day) in the shallow unsaturated SAT column rendered DO of about 2 mg/L to the influent of the saturated SAT column. Phosphate was not removed at all in the unsaturated SAT column while complete removal was achieved in the saturated column. Consequently, organic and inorganic compounds were removed under the shallow aquifer condition as effectively as was in deep aquifer, except for the release of ammonium and relatively high DO into the saturated SAT column.