• 한국환경과학회지
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• 제24권4호
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• pp.471-480
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• 2015

Hydrologic component analysis was conducted to investigate water budget characteristics the Oedocheon watershed, Jeju Island. For this purpose, integrated SWAT-MODFLOW model was applied to this watershed for continuous surface water-groundwater modeling. Pasture and forest-deciduous are the major land use types and these affect general hydrologic component ratio. The spatio-temporal groundwater recharge can be obtained from SWAT and then distributed groundwater recharge can be reproduced by MODFLOW. The groundwater level variation was simulated with distributed groundwater pumping data. The water budget in this watershed was compared with the previous estimated result by Jeju-Do(2013). As this result considered discharge to the coastal side, the discrepancy was found. However, it was found that the overall tendency of both analyses were similar.

• 한국지하수토양환경학회지:지하수토양환경
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• 제24권5호
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• pp.17-30
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• 2019

Intensive agricultural development in Mexicali valley, Baja-California, Mexico, has induced tremendous strain on the limited water resources. Agricultural water consumption in the valley mainly relies on diversions of the Colorado River, but their water supply is far less than the demand. Hence, the use of groundwater for irrigation purposes has gained considerable attention. To account for these changes, it is important to evaluate surface water and groundwater conditions based on historical water use. This study identified the effects of agricultural activities on groundwater levels and groundwater recharge in the Mexicali valley (in irrigation unit 16) by a comprehensive MODFLOW Farm process (MF-FMP) numerical modeling. The MF-FMP modeling results showed that the water table in the study area is drawn downed, more in eastern areas. The inflow-outflow analysis demonstrated that recharge to the aquifer occurs in response to agricultural supplies. In general, the model provides MF-FMP simulations of natural and anthropogenic components of the hydrologic cycle, the distribution and dynamics of supply and demand in the study area.

• 대한토목학회논문집
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• 제38권4호
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• pp.517-526
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• 2018

지하수 함양은 기후조건, 토지이용, 수리지질학적 비균질성에 의해 시공간적인 변동성을 나타내므로 통합수문해석에 의한 지하수 함양량의 추정이 필요하다. 본 연구에서는 SWAT-MODFLOW 연계모형을 활용하여 장성지역의 물리적 기반의 일단위 지하수 함양량을 산정하였다. 수문분석은 하천에서의 관측유량과 계산유량의 검보정에 이어 부정류 지하수위의 계산값과 관측값의 비교를 통해 모형의 정확도를 평가하였다. 추정된 수문성분은 상호간에 서로 관련이 깊고, 유역내의 비균질한 인자들인 소유역 경사, 토지이용, 토양종류에 따라 지하수 함양량의 공간적 변동이 크게 나타났다. 통합수문모형은 지표수 및 지하수 수문성분 프로세스의 시공간적 변화를 잘 모의하고 있는 것으로 평가되었다. 추정된 함양량의 평균은 약 20.8%로 나타났다.

• 지질공학
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• 제24권2호
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• pp.217-225
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• 2014

대규모 수막재배 시설은 동절기 수막재배 기간 동안 군집 취수정의 영향으로 지하수위가 하강하고 이로 인해 지하수 취수량 확보에 어려움을 겪고 있다. 본 연구에서는 동절기 수막재배지역에서의 집중취수에 따른 정밀한 지하수위 변화 분석을 수행하고자 한다. 대상지역인 청원군의 수막재배지역을 포함한 소유역의 지하수 유동을 모의하기 위해 3차원 유한차분모형인 MODFLOW를 구축하였으며, 중요한 입력자료인 지하수 함양량 시계열 자료는 유역수문모형 SWAT모형을 이용하여 구하였다. 여기에 수막재배지의 일최저기온과 취수가동시간과의 관계를 통해 지하수 이용량을 추정한 선행 연구(Moon et al., 2012)를 참고하여 취수계획을 수립, 지하수 모델링에 반영하였다. 부정류 모델링의 적합도를 평가하기 위해 동절기의 모의된 지하수위 강하 패턴을 관측지하수위 자료와 비교하였다. 모델링 기간은 수막재배가 본격적으로 이루어지는 2012년 11월부터 2013년 3월까지의 107일간으로 정하였다. 모의결과 동절기 지하수위 관측값과 비교적 유사한 지하수 하강을 재현할 수 있었고, 일최저기온을 이용한 취수계획방식이 다른 수막재배지역의 지하수 유동해석에도 적용가능할 것으로 판단되었다.

• 환경영향평가
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• 제16권4호
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• pp.251-265
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• 2007

In this study, the influence of the construction of a large sized building on the flow and level of groundwater in a metropolitan area was investigated with simulation model MODFLOW for a selected area located in Gangseo-gu, Seoul, where a large business center was scheduled to be built. It was simulated that the groundwater level in the study area was suddenly lowered by the construction of a large building and groundwater in the surrounding area fast flowed into the study area. And even after the construction finished, the falling down of groundwater level consistently continued in some degree. The flow state of groundwater appeared to be the same in both cases where a soil cement wall is applied and where it is not during the construction. But for the case of application of a soil cement wall as the amount of groundwater flowing into the study site became reduced, it was estimated that the time for underground watershed getting far away from the site was also reduced and the influence of a building construction on the surrounding groundwater became reduced. Thus, it is deemed necessary that recharging the spilled ground water and rainfall into the construction area to lessen the abrupt change in flow and level of ground water should be considered in design of construction of a large sized building in a metropolitan area.

• 한국수자원학회논문집
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• 제49권9호
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• pp.741-748
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• 2016

개착식 하상여과에 대해서 실험실 규모의 모형을 구축하고 중사, 왕사, 화산석, 자갈에 대한 단일 여재를 구성하였다. 실험을 통해 투수계수 및 하상 여과에 대한 취수량을 추정하고, 지하수 유동 모델링인 Visual MODFLOW를 통해 탁도 변화에 따라 수정된 투수계수를 적용하고 미치는 영향을 분석하였다. 각 여재마다 22개의 수정 투수계수 시나리오가 적용되었다. 전체 모델링에서 최소 오차는 화산석(2~5 mm)을 여재로 한 경우 상부에서부터 3개 지층에 대해서 20% 감소된 투수계수를 적용한 시나리오다. 이는 화산석의 특성상 탁도를 유발하는 황토가 여재에 흡착되어 상부에서 3번째 지층까지 영향을 미치는 것으로 추정되었다. 또한 입자의 크기가 작은 중사의 경우 5% 감소된 투수계수를 상부에서 두 번째 지층까지 적용한 시나리오에서도 작은 오차 값을 나타냈다.

• 지질공학
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• 제30권2호
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• pp.119-129
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• 2020

Sand dam is a successful water harvesting method in mountainous areas with ephemeral rivers. The success is dependent on several factors including material type, hydrogeology, slope, riverbed thickness, groundwater recharge, and streamflow. In this study, the effect of a sand dam on the groundwater level in the Chuncheon area, South Korea was assessed using the MODFLOW model. Using the model, multiple scenarios were tested to understand the groundwater head before and after the construction of the sand dam. The effect of groundwater abstraction before and after sand dam construction and the sand material type were also assessed. The results show, the groundwater level increases substantially after the application of a sand dam. The comparison of model outputs, simulated groundwater head before and after sand dam application with and without pumping well, shows a clear difference in the head. The material type has also an effect on the groundwater head. As the conductivity of the material increases, the head showed a significant rise.

• 한국환경과학회지
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• 제24권4호
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• pp.495-504
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• 2015

To estimate water balance of Pyosun watershed in Jeju Island, a three-dimensional finite difference model MODFLOW was applied. Moreover, the accuracy of groundwater flow modeling was evaluated through the comparison of the recharge rate by flow modeling and the existing one from water balance model. The modeling result under the steady-state condition indicates that groundwater flow direction was from Mt. Halla to the South Sea and groundwater gradient was gradually lowered depending on the elevation. Annual recharge rate by the groundwater flow modeling in Pyosun watershed was calculated to 236 million $m^3/year$ and it was found to be very low as compared to the recharge rate 238 million $m^3/year$ by the existing water balance model. Therefore, groundwater flow modeling turned out to be useful to estimate the recharge rate in Pyosun watershed and it would be available to make groundwater management policy for watershed in the future.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.466-474
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• 2008

The purpose of this study was to comparatively analyze the measured values and modelling values when a sample mountain was cut and thereby, assess the fitness of the prediction model. For this purpose, the researcher analyzed the relationship between the groundwater levels measured at 7 monitoring holes set within the area of the underground flow prediction model and the levels of the groundwater monitoring holes before and after mountain cutting. As a result of this analysis, it was found that the MODFLOW program itself was limited and uncertain in terms of calibration of the modelling values. Since the model was based on the assumption that the same amount of rainfalls would permeate into the ground when the sample mountain area was cut up to 50m high, it was deemed inevitable that the result of modelling was different from the actual measurement.

• 자원환경지질
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• 제44권5호
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• pp.433-442
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• 2011

우리나라의 지하수관리는 연간 지하수 함양량을 기반으로 수행되어 왔으나 지히수 함양량과 지표수-지하수 상호작용은 시공간적으로 변동하는 양이므로 지속적인 모니터링과 동적인 분석을 통해 지하수자원의 지속가능성이 평가되어야 할 것이다. 본 연구에서는 무심천 유역을 대상으로 지표수-지하수 통합해석 모형인 SWAT-MODFLOW를 이용하여 다양한 지하수 양수 시나리오(무양수 및 현 이용량의 1~3배)에 대한 수문성분 해석을 수행하였다. 현 이용량으로 양수하는 경우가 비교적 지속가능한 개발량으로 판단되었는데 이때 연간 기저유출량은 16%, 대수층 저류량은 27 mm 감소하는 것으로 나타났다. 지하수의 지속가능성을 평가하기 위해서는 지하수 이용에 따른 수문학적, 생태학적, 사회 경제적, 기술적 영향을 평가하는 총체적 접근법이 도입되어야 하며 이를 위해서는 물리적인 분석과 함께 지역사회의 합의 또한 중요한 의사결정 방식이라고 판단되었다.