• Journal of the Korean GEO-environmental Society
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• v.16 no.9
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• pp.13-21
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• 2015

Recently, land subsidence and sinkhole are generated due to a change in the groundwater level in the city. For this reason, the necessity for management of stable underground water level is on the rise. In this study, it was conducted for the underground structure that passes through the lower of bus transfer center construction site to examine the influence on the stability for underground structures to changes in the groundwater level and effective stress, the coupled finite element analysis and structural analyses were performed to evaluate stability for underground structure. It is to secure stability for underground structures according to underground water level declines. In this way, effective construction management will be made by previewing and forecasting the influence on the ground behavior and adjacent structures due to changes in the groundwater level.

• The Journal of Engineering Geology
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• v.32 no.2
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• pp.257-270
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• 2022

This study evaluated the hydraulic factors contributing to the decreasing groundwater levels across Jeju island. Time-series data for groundwater level, precipitation, and groundwater usage and information on land use were acquired, and the correlations among them were analyzed to evaluate the causes of the decreasing groundwater. The effects of precipitation and groundwater usage on the fluctuations of groundwater level were quantified using response surface analysis and sensitivity analysis, and methods for groundwater quantity management by region were proposed. The results showed that the rate of groundwater decrease in the western region was larger than that in the eastern region. For the eastern region, the influence of precipitation was large and the rate of decrease in the groundwater level was relatively small. The geological formation of this part of the island and continuous seawater intrusion suggest that although the absolute amount of groundwater extracted for use was large, the decrease in the groundwater level was not seen to be great due to an increase in pressure by seawater intrusion. Overall, precipitation and groundwater usage had the greatest effect on the amount of groundwater in the western region, and thus their data would be most useful for informing groundwater management, whereas other factors (e.g., sea level and the location of the freshwater-seawater transition zone) must be considered when understanding Jeju's eastern region. As the characteristics of groundwater level fluctuations in the eastern and western regions are distinct, an optimal management plan for each region should be proposed to ensure the efficient management of groundwater quantity.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.434-434
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• 2012

현재 지하차도 설계 지하수위는 철도, 지하철 및 공동구의 설계기준과 기존사례를 준용하여 지표면 하 1.0 m를 기준으로 설계하고 있으며, 지하차도 설계시 지하수위 적용에 대한 명확한 기준과 그에 따른 설계와 유지관리지침 등이 마련되어 있지 않아 부득이 기존의 공법을 그대로 답습하고 있다. 또한 대부분 과다설계 요인과 친환경적이지 못하다는 지적받고 있는 부력앵커공법을 적용하고 있는 실정이다. 본 연구에서는 영종하늘도시 사업지구에 시공중인 지하차도 구조물과 관련하여 지하차도 구조물 건설에 따른 지하수 흐름 변화 특성을 평가하여 유도배수공법의 효과를 검토하였다. 지하차도 건설에 의한 흐름변화 분석을 위하여 3차원 지하수 MODFLOW 프로그램을 이용하였으며 지하차도 건설전, 후에 대하여 프로그램을 수행하였다. 수행 결과 지하차도 건설 전 유역의 평균 지하수위는 지표하 1~2m 이상으로 비교적 높은 지하수를 형성하고 있는 것으로 평가되었다. 유도배수공법을 적용한 지하차도 건설 후 지하차도 주변부 지하수위는 건설전에 비하여 약 3~4 m 하강하는 것으로 분석되었으며, U-type 종점부는 지표하 최소 6 m 이상, 시작부는 지표하 최소 3.4 m 이상 아래에 형성되는 것으로 평가된다. 연구 결과는 향후 지하차도 유도배수공법 평가의 기초자료로 활용할 수 있을 것으로 판단된다.

• Journal of Korea Water Resources Association
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• v.50 no.12
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• pp.815-825
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• 2017

Groundwater management vulnerability was assessed using TOPSIS (Techniques for Order Performance by Similarity to Ideal Solution) for 21 administrative districts in Nakdong river basin. Ten indicators were selected for 21 administrative districts in the Nakdong river basin by collecting natural, human, and social data sets. The selected indicators were standardized using rescale method, and each indicator was weighted by considering the questionnaire of expert group. The results of the weights determination survey showed that the annual average groundwater level index was 0.157 and this is the highest value. The annual average precipitation index was 0.154 and the annual groundwater recharge index was 0.152. The lowest weighted index was 0.043 for population density. Finally, the result of assessment of groundwater management vulnerability showed that Sangju-si was the most vulnerable to groundwater management among 21 administrative districts in Nakdong river basin because the annual average precipitation, annual average groundwater recharge, and annual average groundwater use indicators were highly vulnerable. The second and the third vulnerable regions were Yecheon-gun and Haman-gun respectively. The assessment of groundwater management vulnerability for the five major river basins in Korea can be a essential basis for the establishment of groundwater management policy.

• Journal of Korea Water Resources Association
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• v.53 no.5
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• pp.337-345
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• 2020

In order to provide information for proper management of groundwater resources, an analysis of the effects of precipitation and groundwater withdrawal on groundwater levels is needed. In this study, we analyzed the correlation of precipitation-groundwater level and groundwater withdrawal-groundwater level using time series data converted by normalized standard deviation (Nor.St.Dev) and cross correlation coefficient (CCC) for nine groundwater monitoring wells in the middle mountainous area in the southeastern Jeju Island. First, the CCCs of precipitation-groundwater level were estimated using daily time series data, and the low CCCs of up to 0.3 were obtained. However, the result of using the Nor.St.Dev showed a clearer correlation by obtaining a CCC of up to 0.8. In addition, in most cases, precipitation variability and groundwater level variability had positive CCCs, whereas groundwater withdrawal variability and groundwater level variability had negative CCCs. Therefore, the groundwater level in this study area was largely influenced by precipitation with little effect of groundwater withdrawal. Lastly, as a result of analyzing the relative effects of Seongpanak and Gyorae rainfall station on the groundwater level, the rainfall at the relatively downstream Gyorae rainfall station has more influence. The analysis method used in this study can be easily used for analyzing the effects of precipitation and groundwater withdrawal on groundwater level variability in other regions in the future.

• The Journal of Engineering Geology
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• v.23 no.2
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• pp.105-115
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• 2013

Increasing the river cross-section by barrage construction causes rises in the average river water levels and discharge rates in the rainy season. The time series patterns for groundwater levels measured at 23 riverside monitoring wells along the lower Nakdong River are compared for two cases: before and after water-filling at the Changnyeong-Haman Barrage. Monthly average groundwater levels indicate a distinct increase in groundwater levels in the upstream riverside close to the barrage. River-water level management by barrage gate control in August, during the rainy season, resulted in a 0.1 m decrease in groundwater levels, while water-filling at the barrage in December caused a 1.3 m increase in groundwater levels. The results of hierarchical cluster analysis indicate that seven groundwater monitoring wells and river water levels were in the same group before barrage construction, but that this number increased to 14 after barrage construction. Principal component analysis revealed that the explanation power of two principal components corresponding to river fluctuation, PC1 and PC2, was approximately 82% before barrage construction but decreased to 45% after construction. This finding indicates that the effect of the river level component that contributes to change in groundwater level, decreases after barrage construction; consequently, other factors, including groundwater pumping, become more important. Continuous surveying and monitoring is essential for understanding change in the hydrological environment. Water policy that takes groundwater-surface water interaction into consideration should be established for riverside areas.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.377-377
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• 2023

기후변화로 인한 국내 수문기상 환경의 변화는 기존의 강수 패턴의 변화를 야기하고, 이는 수문학적 측면에서 유역 내 지하수 함양량의 변화를 야기할 수 있다. 상시 취수가 가능한 대규모 하천 인근 지역 외의 지역은 가용 수량의 확보를 위하여 생·농·공 용수 확보를 위하여 지하수를 적극적으로 이용하고 있다. 유역의 수자원 관리를 위하여 하천, 저수지, 댐 등으로 대표되는 지표수자원의 관리와 함께 지하수자원 관리의 중요성이 대두되고 있다. 지하수자원의 관리를 위해서는 기존 지하수 이용시설의 지하수 이용량에 대한 정확한 정보를 수집하는 것이 중요하지만 지하수 함양량을 정량적으로 평가하는 것 또한 매우 중요하다. 지하수 함양량을 산정하기 위한 방법으로는 물수지 분석, MIKE, SWAT 등 모형을 이용한 분석 등 다양한 평가 방법이 있으나 유역의 지하수 함양에 영향을 줄수 있는 수문환경에 대한 정확한 정보가 있어야 하기 때문에 권역 내 표준유역 전반에 대한 지하수 함양량을 산정하기 어려운 단점이 있다. 본 연구에서는 지하수위 관측자료와 강수량 관측자료를 이용한 지하수위 변동법을 적용하여 표준유역 별 지하수 함양량을 산정하였다. 최근 5년간의 자료를 이용하여 표준유역 별 지하수 함양량 산정 결과를 제안함으로써 표준유역 단위 수자원 관리에 기여하고자 하였다. 본 연구 결과는 표준 유역 별 가뭄 대응 방안을 도출하는데 기초 자료로써 활용 될 수 있을 것으로 기대된다

• Journal of the Korean Geotechnical Society
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• v.21 no.7
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• pp.63-72
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• 2005

Grounwater level applied on dredged and reclaimed clay layer was assumed to be the same value under design criterion as field test one, but actually differences are found through the monitoring test. In this study, a case study of measuring residual groundwater level is performed in ground improvement construction of Gwangyang container terminal and hinterland. With priority given to residual groundwater level measured during construction and management period of 9 years, it is investigated that residual groundwater level (R. GWL) could be applied reasonably to the design, construction, and use stages of the container harbor and land development.

• The Journal of Engineering Geology
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• v.33 no.3
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• pp.461-474
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• 2023

The study area is located in Hyeonseo-myeon and Andeok-myeon of Cheongsong-gun, Korea around the Yeongcheon dam waterway tunnel, and in this paper, it is analyzed whether the groundwater level is recovered or not compared to groundwater level before waterway tunnel construction by measuring the groundwater level of 156 wells which were installed in areas near and away from the waterway tunnel. From September 2017 to August 2018, the groundwater level of the well was measured at least once a month, and as a result of groundwater level observation survey, the groundwater level of wells distributed in the directly affected zone by the waterway tunnel is relatively lower than that of the indirectly affected zone apart from the waterway tunnel. These results are estimated to be predominantly affected by the effect of waterway tunnel acting on geologic discontinuities rather than by terrain conditions, i.e. groundwater flows being leaked to the waterway tunnel through direct or indirect channels. Continuous monitoring and further investigation will be required to maintain groundwater facilities and preserve groundwater environments in the future.

• Journal of Korea Water Resources Association
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• v.55 no.3
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• pp.191-203
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• 2022

This study is a follow-up study of vulnerable areas according to the vulnerability assessment of groundwater resource management in Korea. In this study, an optimal operation plan for groundwater resource management was proposed for areas vulnerable to groundwater resource management in Korea derived from previous studies. Prior to presenting the optimal operation plan for groundwater resource management, this study grasped the current status of changes in groundwater level and seawater penetration area for vulnerable areas using MODFLOW, a groundwater flow analysis program. As a result of the analysis using basic data for 10 years from 2009 to 2018, the groundwater level fell and the sea infiltration area increased. The final purpose of this study, the optimal operation plan for groundwater resource management, was selected as a total of four alternatives that can be expected to have positive effects to increase groundwater level and reduce seawater penetration. As a result of analyzing the amount of change in groundwater level and seawater penetration by applying the selected optimal operation plan, positive effects were found in all methods. It is expected that the optimal operation plan for groundwater resource management proposed in this study will be applied not only to vulnerable areas of groundwater resources in Korea but also to areas requiring development to establish efficient groundwater resource management measures.