• 한국터널지하공간학회 논문집
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• 제19권2호
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• pp.109-120
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• 2017

터널 내 지하수 침투는 터널붕괴와 그에 따른 지반침하의 주요 원인 중 하나이다. 따라서 터널굴착 중 시간에 따른 지하수 침투량과 간극수압 변화를 적절히 예측하는 것이 중요하다. 실무에서는 균질한 지반조건으로 가정하는 Goodman의 산정법을 사용하여 지하수 침투량을 계산하지만, 터널굴착 중 지하수위 강하와 깊이에 따른 투수계수 변화를 고려하지 않아 설계단계에서 지하수 유입량을 과다하게 산정할 우려가 있다. 따라서 본 연구에서는 지하수위 강하 및 깊이별 투수계수의 감소를 적용한 매개변수분석을 통해 지하수 유입량 변화를 분석 비교하였으며, 시간에 따른 지하수 침투량 변화와 지하수위 및 간극수압 분포 변화를 분석하기 위해 비정상류 해석을 수행하였다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2011년도 학술발표회
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• pp.18-18
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• 2011

Climate change is impacting and will increasingly impact both the quantity and quality of the world's water resources in a variety of ways. In some areas warming climate results in increased rainfall, surface runoff, and groundwater recharge while in others there may be declines in all of these. Water quality is described by a number of variables. Some are directly impacted by climate change. Temperature is an obvious example. Notably, increased atmospheric concentrations of $CO_2$ triggering climate change increase the $CO_2$ dissolving into water. This has manifold consequences including decreased pH and increased alkalinity, with resultant increases in dissolved concentrations of the minerals in geologic materials contacted by such water. Climate change is also expected to increase the number and intensity of extreme climate events, with related hydrologic changes. A simple framework has been developed in New Zealand for assessing and predicting climate change impacts on water resources. Assessment is largely based on trend analysis of historic data using the non-parametric Mann-Kendall method. Trend analysis requires long-term, regular monitoring data for both climate and hydrologic variables. Data quality is of primary importance and data gaps must be avoided. Quantitative prediction of climate change impacts on the quantity of water resources can be accomplished by computer modelling. This requires the serial coupling of various models. For example, regional downscaling of results from a world-wide general circulation model (GCM) can be used to forecast temperatures and precipitation for various emissions scenarios in specific catchments. Mechanistic or artificial intelligence modelling can then be used with these inputs to simulate climate change impacts over time, such as changes in streamflow, groundwater-surface water interactions, and changes in groundwater levels. The Waimea Plains catchment in New Zealand was selected for a test application of these assessment and prediction methods. This catchment is predicted to undergo relatively minor impacts due to climate change. All available climate and hydrologic databases were obtained and analyzed. These included climate (temperature, precipitation, solar radiation and sunshine hours, evapotranspiration, humidity, and cloud cover) and hydrologic (streamflow and quality and groundwater levels and quality) records. Results varied but there were indications of atmospheric temperature increasing, rainfall decreasing, streamflow decreasing, and groundwater level decreasing trends. Artificial intelligence modelling was applied to predict water usage, rainfall recharge of groundwater, and upstream flow for two regionally downscaled climate change scenarios (A1B and A2). The AI methods used were multi-layer perceptron (MLP) with extended Kalman filtering (EKF), genetic programming (GP), and a dynamic neuro-fuzzy local modelling system (DNFLMS), respectively. These were then used as inputs to a mechanistic groundwater flow-surface water interaction model (MODFLOW). A DNFLMS was also used to simulate downstream flow and groundwater levels for comparison with MODFLOW outputs. MODFLOW and DNFLMS outputs were consistent. They indicated declines in streamflow on the order of 21 to 23% for MODFLOW and DNFLMS (A1B scenario), respectively, and 27% in both cases for the A2 scenario under severe drought conditions by 2058-2059, with little if any change in groundwater levels.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 총회 및 춘계학술발표회
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• pp.259-262
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• 2003

In the Republic of Korea, Ministry of Construction & Transportation and Korea Water Resources Corporation manage the national groundwater monitoring network at the 169 stations and will organize the supplementary groundwater monitoring network at the 10,000 stations by 2011 year. The method that organizes the monitoring network was developed using the Analytic Hierarchy Process with pairwise comparison. Several estimation factors for the estimating every district were selected to reflect each district conditions. Their weighting value was decided by pairwise comparison and questions to the experts about groundwater The optimal number of groundwater monitoring well was calculated through the developed method. To verify this method, groundwater was monitored in Jeonju city by way showing the example. The study area In Jeonju city needs 7 stations for the supplementary groundwater monitoring network. The results monitored in 7 stations inferred the groundwater level around the study area by Kriging. The mean of residual between inferred groundwater level value from Kriging and actual groundwater level is rather low. Furthermore, the mean and standard deviation of residual between inferred groundwater level change and actual groundwater change is much lower. The Fact that 7 monitoring stations are sufficient for observing the groundwater condition in the study area makes it possible for suggested monitoring number to be proper.

• 한국지하수토양환경학회지:지하수토양환경
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• 제24권2호
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• pp.23-37
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• 2019

To evaluate the available groundwater supply to the agricultural water demand in the future with the climate change scenarios for 40 sub-regions in Jeju Island, groundwater recharge and the available groundwater supply were estimated using water balance analysis method. Groundwater recharge was calculated by subtracting the actual evapotranspiration and direct runoff from the total amount of water resources and available groundwater supply was set at 43.6% from the ratio of the sustainable groundwater capacity to the groundwater recharge. According to the RCP 4.5 scenario, the available groundwater supply to the agricultural water demand is estimated to be insufficient in 2020 and 2025, especially in the western and eastern regions of the island. However, such a water shortage problem is alleviated in 2030. When applying the RCP 8.5 scenario, available groundwater supply can't meet the water demand over the entire decade.

• 한국지하수토양환경학회지:지하수토양환경
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• 제18권1호
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• pp.1-5
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• 2013

Global climate changes affect the local hydrologic cycle, and subsequently, require changes in water resource management strategies of Korea. Variations in precipitation and urbanization have adverse effects on the reasonable and efficient utilization of groundwater resources. Groundwater management strategies of Korea have been implemented based on the evaluation of "sustainable yield", which is calculated from the amount of annual recharge. However, this sustainable yield has no consideration of natural discharge and dynamic equilibrium of the groundwater system. Therefore, for the effective groundwater management strategies of the following decades, we need representative and reliable observations, and have to develop methods for the systematic analysis and interpretations of the data to draw valid information in linkage of natural and societal environmental changes.

• 지질공학
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• 제29권3호
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• pp.265-277
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• 2019

지구 온난화에 따른 기후 변화, 강수량, 강우 강도, 빈도 그리고 강우 유형의 변화는 지하수 함양과 지하수위 변동에 큰 영향을 미친다. 전 세계적인 총 저수량 변화를 파악하는데, GRACE의 월 중력값 이용되어지고 있다. 그러나 지하수위의 공간적인 분포를 표현하기가 쉽지 않으므로, GRACE자료와 지하수위 자료를 정량적으로 연관시키기는 쉽지 않다. 본 연구에서는 세 가지 국지적인 보간법(크리깅, 역 거리 가중값 및 자연 인접)을 이용하여 2002년부터 2016년 까지 국내 지하수 함양 변화량의 공간적인 분포를 추정하였다. 그리고 추정된 월평균 지하수 함양 변화량과 GRACE의 월별 지하수 저장량 변화값을 비교하였다. GRACE자료와 실측 지하수자료의 함양량 변동값은 미약하지만 시간이 경과할수록 감소추세를 보이고 있으며, 연구기간 동안에 지하수 함양 변화량의 평균값은 -0.01 cm/month, 중앙값은 -0.02 cm/month로 산정되었다.

• 한국습지학회지
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• 제13권3호
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• pp.377-384
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• 2011

강수량변화가 도시 및 해안지역의 지하수함양량에 미치는 영향을 파악하기 위하여 부산광역시 수영구를 포함하는 광역 지하수유역에 강수량자료를 변화시켜 지하수함양량을 산정하고 강수량증감에 따른 지하수함양량의 변화특성을 분석하였다. 그 결과, 강수량 증감에 따라 지하수함양량의 증감량은 차이가 있으나 강수량과 지하수함양량의 변화 양상은 동일한 경향을 나타내었다. 강수량의 변화에 대한 지하수함양률의 변화폭이 최근으로 올수록 적어지는 경향을 나타내었다. 또한 연도가 증가함에 따라 지하수함양률이 감소하는 추세를 나타내었다. 강수량 변화 시의 지하수함양량의 전체 평균 변화율은 강수량이 10 % 증가 시에는 2.23 %, 10 % 감소 시에는 2.20 %, 20 % 증가 시에는 4.39 %, 20 % 감소 시에는 4.36 %로 강수의 변화율에 비하여 지하수함양량은 적은 변화율을 보였다. 이들 결과로부터 강수량의 변화율에 비하여 지하수함양률의 변화가 크지 않음을 알 수 있었다. 따라서 도시지역에서 강수량이 변화할 시에는 지하수함양량의 변화율이 이에 미치지 못함으로 직접유출에 미치는 영향이 그 양만큼 커지게 되어 도시홍수의 발생가능성이 지속적으로 증가하게 됨을 알 수 있었다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제26권5호
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• pp.60-76
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• 2021

The concept of resilience seems applicable for sustainable groundwater management. The resilience is broadly defined as the ability of a system to resist changes by external forces (EFs), and has been used for disaster management and climate change adaptation, including the groundwater resilience to climate change in countries where groundwater is a major water resource, whereas not yet in the geological society of South Korea. The resilience is qualitatively assessed using the absorptive, adaptive, and restorative capacity representing the internal robustness, self-organization, and external recovery resources, respectively, while quantitatively using the system impact (SI) and recovery effort (RE). When the groundwater is considered a complicated system where physicochemical, biological, and geological components interact, the groundwater resilience can be defined as the ability of groundwater to maintain the targeted quality and quantity at any EFs. For the quantitative assessment, however, the resilience should be specified to an EF and measurable parameters should be available for SI and RE. This study focused on groundwater resilience to two EFs in urban areas, i.e., pollution due to land use change and groundwater withdrawal for underground structures. The resilience to each EF was assessed using qualitative components, while measurements for SI and RE were discussed.

• 한국지하수토양환경학회지:지하수토양환경
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• 제27권2호
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• pp.61-75
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• 2022

This study evaluated the potential threat of agricultural and human activities to groundwater in the Noseong stream watershed, a typical agricultural area, through hydrogeochemical characteristics and microbial community analyses. The groundwater in the study area was Ca-SO₄ and Ca-HCO₃ types alluvial aquifer mainly used for agricultural and living purposes, and contained high levels of NO₃^- and Cl^- ions generated from anthropogenic sources such as fertilizer, livestock wastewater, and domestic sewage. Proteobacteria was most abundant in all samples with an average of 46.1% while Actinobacteria, Bacteroidetes, and Cyanobacteria were dominant on an occasional basis. The prevalence of aerobic bacteria such as the genus Mycobacterium, Flavobacterium, and Sphingomonas suggests that groundwater was well connected with the surface layer. The potential pathogen Mycobacterium was detected in most samples, and other pathogenic bacteria were also widely distributed, indicating the vulnerability to contamination. Therefore, an integrated management system is required to secure the sustainable use of groundwater in agricultural areas with high groundwater dependence.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2018년도 학술발표회
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• pp.145-145
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• 2018

Small islands rely heavily on groundwater resources in addition to rainwater as the source of freshwater since surface water bodies are often absent. The groundwater resources are vulnerable to sea level rise, coastal flooding, saltwater intrusion, irregular pattern of precipitation resulting in long droughts and flash floods. Increase in population increases the demand for the limited groundwater resources, thus aggravating the problem. In this study, the effects of climate change on Tongatapu Island, Kingdom of Tonga, a small island in Pacific Ocean, are investigated using a sharp interface transient groundwater flow model. Twenty nine downscaled General Circulation Model(GCM) predictions are input to a water balance model to estimate the groundwater recharge. The temporal variation in recharge is predicted over the period of 2010 to 2099. A set of GCM models are selected to represent the ensemble of 29 models based on cumulative recharge at the end of the century. This set of GCM model predictions are then used to simulate a total of six climate scenarios, three each (2010-2039, 2040-2069, and 2070-2099) under RCP 4.5 and RCP 8.5. The impacts of predicted climate change on groundwater resources is evaluated in terms of freshwater volume changes and saltwater ratios in pumping wells compared to present conditions. Though the cumulative recharge at the end of the century indicates a wetter climate compared to the present conditions the large variability in rainfall pattern results in frequent periods of groundwater drought leading to saltwater intrusion in pumping wells. Thus for sustaining the limited groundwater resources in small islands, implementation of timely assessment and management practices are of utmost importance.