• Proceedings of the Korean Society of Agricultural Engineers Conference
• /
• 2003.10a
• /
• pp.307-310
• /
• 2003

The purpose of this study was to obtain optimal amount of groundwater development for a rural small watershed. The optimal amount of groundwater development in this experimental watershed is 13.8 %($0.67{\times}10^6m^3$) of the annual rainfall by SCS-CN method. The Visual MODFLOW analyses showed the optimal amount of groundwater development were 14.9 %($0.72{\times}10^6m^3$) of the annual rainfall.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2006.04a
• /
• pp.259-262
• /
• 2006

본 연구는 지하처분연구시설(URT : Underground Research Tunnel)시설 건설공사와 관련하여 굴착 후의 지하수유동체계 변화를 예측하기 위하여 수행되었다. 지하수유동체계 모사를 위해 사용된 모델은 연속체 매질 개념의 Visual Modflow이며, URT 주변의 시추공에서 조사된 자료를 초기 입력자료로 이용하였다. 1단계 터널굴착 후에 계측된 지하수위 및 터널 내 지하수 유입량을 토대로 모델교정을 수행하였고, 교정된 모델을 이용하여 2단계 터널굴착 후의 지하수유동체계를 예측하였다. 1단계 굴착 후 약 4.3m의 수위강하가 발생한 KP-2번공은 2단계 굴착 후에는 약 0.05m의 수위강하가 예측되었다. 또한 2단계 굴착 후의 지하수위는 터널 입구를 기준으로 약 108m지점부터 터널 종점부 175m까지는 터널 상부에 분포하며, 종점부 175m지점에서는 지하수위가 터널 천장(roof)부로부터 약 12.7m 상부에 위치하는 것으로 예측되었다. 지하수위의 강하범위는 터널 중심부로부터 반경 약 300m까지 발생되는 것으로 예측되었고, 예상 지하수 유입량은 24.7ton/day로 1단계 공사 후보다. 약 2.7ton/day 증가하며, 공동굴착 전 터널 중심부의 지하수가 지표까지 도달하는 시간은 약 39.8년이 소요되는 것으로 나타났다.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2015.05a
• /
• pp.295-295
• /
• 2015

강우의 시 공간적 불균형이 심한 우리나라는 수자원 확보 및 관리가 어려움에 따라 신규 수자원 확보와 기존 수자원 관리의 중요성에 대한 인식이 높아지고 있다. 최근 대체수자원으로서 대두되고 있는 지하수는 지표수에 비해 이용지점에서 바로 취수하여 사용이 가능하다는 장점이 있으나, 오염이 진행되면 복구에 상당한 기간과 비용이 소요됨에 따라 철저한 관리가 필요하다. 특히 해안지역 수자원의 경우, 내륙지역에 비해 하천이 발달해 있지 않아 지하수에 대한 높은 의존도에 따른 수량적 문제와 해수와 접해있는 면적이 많음에 따라 지하수와 해수간의 유동으로 인한 수질적 문제로 지하수 관리가 더욱 어렵다. 이에 본 연구는 지하수유동해석프로그램인 Visual MODFLOW의 SEAWAT model을 이용하여 지하수위 변화에 따른 해수침투의 영향을 판단하고자 하였다. 연구지역은 태안지역의 근흥1, 근흥2 관측소의 지하수위 데이터를 사용하였으며, 2008 ~ 2014년 까지 매년 지하수위 변동에 따라 해수침투 영향을 분석하였다. 이와 함께 해수침투 영향 판단 인자인 EC, TDS는 각 관측소 데이터를 통한 환산 및 분석 진행하고, $Cl/HCO_3$ 몰비는 참고문헌을 인용하여 모델링에 의한 해수침투 영향과 관측자료 및 이온분석을 통한 영향을 비교하였다.

• Journal of the Korean Geosynthetics Society
• /
• v.14 no.2
• /
• pp.45-55
• /
• 2015

In Incheon area, 1960s of economic development planning and heavy industry center of efforts industrial park and port facilities, It is industrial land reclamation by coastal landfill, these industrial park has the characteristics of Low permeability lipid is embedded in the silty sand that was dredged. In this study, To evaluate the heavy metal adsorption ability to filter of drains that have been developed as environmentally friendly materials by applying the effective zeolite to heavy metal adsorption for soil pollution purification suitable for geological characteristics of Incheon. soil pollution Survey data and Literature search, which is the current through the industry, the most problematic was set to Cadmium (Cd) and Copper(Cu), Lead (Pb). and Using the Numerical Analysis using the Visual Modflow, was presented the most efficient drains set interval and format.

• The Journal of Engineering Geology
• /
• v.14 no.3 s.40
• /
• pp.287-300
• /
• 2004

By using a simple conceptual model, a sensitivity analysis is performed to examine the effects of changing model parameters on the model outputs, the groundwater discharge and the radius of influence, induced by tunnel construction. The results indicate that the model outputs are most sensitive to the tunnel depth and the hydraulic conductivity, and their sensitivities vary with time. It is also revealed that the sensitivity of the specific yield in- creases constantly with time, and therefore it is as important as the hydraulic conductivity for constructing a wet-system tunnel. A transient model is suggested to simulate the stepwise tunnel excavation and the watertight lining. The model is used for a tunnel construction site to predict groundwater mow into the tunnel and the transient response of the surrounding aquifer system. The predicted results are highly sensitive to the hydraulic conductivites assigned by model calibration. Thus, a postaudit should be made to reduce the uncertainty of the predictive model.

• Journal of Soil and Groundwater Environment
• /
• v.17 no.3
• /
• pp.39-48
• /
• 2012

Visual MODFLOW, a three dimensional groundwater flow model, was used to analyze effects of a weir construction in an alluvial stream on the nearby groundwater flow system. A hypothetical conceptual model was developed to investigate how the groundwater level and the water budget could change after a weir construction depending on the location of tributary streams. A site example, dealing with the Juksan weir installed in the Yeongsan River, was also demonstrated to predict the effects of the weir construction. Model results show that impacts of a weir construction on the groundwater flow system greatly vary depending on how far a tributary is located and whether it is located downstream or upstream from the weir. Therefore, consideration of the location of tributaries in planning the location of a weir could effectively minimize the impacts of a weir construction on the groundwater flow system. It is also demonstrated that model results are highly dependent upon how the model is dealing with small tributaries and agricultural drainage channels, which can be easily found nearby the main streams, acting as major water bodies for groundwater discharge. The model for the Juksan area shows that the weir construction will change the direction of groundwater flow in some areas, leading to changes of groundwater quality and interaction of the Yeongsan River to the aquifer from a gaining to a losing stream. The model also predicted the areas where rise of groundwater level caused by the Juksan weir could adversely affect plant growth, and thereby suggested installing new drainage channels as a countermeasure to drawdown the groundwater level.

• Journal of Korean Society of Disaster and Security
• /
• v.10 no.1
• /
• pp.19-27
• /
• 2017

In recent years, ground subsidence has been frequently occurred by underground cavities due to the excessive groundwater inflow, caused by poor construction and management, during tunnel excavation and underground structure construction. In this study, a numerical model (SEEFLOW3D) was developed to estimate groundwater fluctuations for saturated-unsaturated poros media, evaluates the impact on ground excavation with open cut and non-open cut scenarios. In addition, the visual MODFLOW was applied to demonstrate the verification of the model compared with both results. Our results indicated that the RMSE and NRMSE was obtained to range over -3.95~5.7% and 0.56~4.62%, respectively. The developed model was expected to estimate groundwater discharges and apply analysis tool for optimum design of waterproof wall in future.

• Journal of the Korean GEO-environmental Society
• /
• v.17 no.8
• /
• pp.29-37
• /
• 2016

In order to prevent leakage of contaminants in offshore landfill, vertical barrier should be installed. Vertical barrier should be installed at designed depth of seabed to prevent the horizontal transport of contaminant in the subsurface. In this study, the seepage and contaminant transport in the subsurface according to embedded depth of vertical barrier were analyzed by using 2-D finite element analysis program SEEP/W and 3-D finite difference analysis program Visual Modflow. Numerical modelling results show that seepage flux and contaminant transport in seabed was greatly reduced when vertical barrier was installed at certain depth of low permeable layer. Therefore, the determination of minimum embedded depth for preventing contaminant leakage is helpful to design the economical vertical barrier.

• Journal of Soil and Groundwater Environment
• /
• v.21 no.1
• /
• pp.61-71
• /
• 2016

Visual MODFLOW was used for quantifying stream-aquifer interactions caused by seasonal groundwater pumping. A hypothetical conceptual model was assumed to represent a stream-aquifer system commonly found in Korea. The model considered a two-layered aquifer with the upper alluvium and the lower bedrock and a stream showing seasonal water level fluctuations. Our results show that seasonal variation of the stream depletion rate (SDR) as well as the groundwater depletion depends on the stream depletion factor (SDF), which is determined by aquifer parameters and the distance from the pumping well to the stream. For pumping wells with large SDF, groundwater was considerably depleted for a long time of years and the streamflow decreased throughout the whole year. The impacts of return flow were also examined by recalculating SDR with an assumed ratio of immediate irrigation return flow to the stream. Return flow over 50% of pumping rate could increase the streamflow during the period of seasonal pumping. The model also showed that SDR was affected by both the conductance between the aquifer and the stream bed and screen depths of the pumping well. Our results can be used for preliminary assessment of water budget analysis aimed to plan an integrated management of water resources in riparian areas threatened by heavy pumping.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2022.05a
• /
• pp.450-450
• /
• 2022

The study aims to develop scenarios for efficient groundwater use using existing wells in order to prepare for an eventual drought. In the recent decades, droughts are not only intensifying, but they are also spreading into territories where droughts used to be less intense and relatively infrequent. With the increasing disaster, efficient groundwater use is urgently needed not only to prevent the problem of groundwater depletion but also drought risk reduction. Thus, the research addressed the problem of efficient aquifer use as source of water during drought and emergencies. The research focused on well network system applied to Yanggok-ri in Korea using simulation models in visual MODFLOW. The approach consists to variate groundwater pumping rate in the most important wells used for irrigation across the study area and evaluate the pumping effect on water level fluctuation. From the evaluation, the pumping period, appropriate pumping rate of each well and the most vulnerable wells are determined for a better groundwater management. The project results divide the study area into two different regions (A and B), where the wells in the region A (western part of the region) show a crucial drop in water level from May to early July and in august as consequence of water pumping. While wells in region B are also showing a drawdown in groundwater level but relatively less compare to region A. The project suggests a scenarios of wells which should operate considering water demand, groundwater level depletion and daily pumping rate. Well Network System in relevant project, by pumping in another well where water is more abundant and keep the fixed storage in region A, is a measure to improve preparedness to reduce eventual disaster. The improving preparedness measure from the project, indicates its implication to better groundwater management.