• Journal of Korea Water Resources Association
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• v.41 no.1
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• pp.27-34
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• 2008

Groundwater development in coastal areas induces saltwater intrusion. In many cases amount of groundwater resources available for development is limited by a pre-specified limit of additional saltwater intrusion. In this paper a simple equation is developed to assess available groundwater resources which depends on the constraint of acceptable additional saltwater intrusion. Strack#s single-potential analytical solution is used to derive the equation. Available groundwater increases as more additional intrusion is allowed. However, critical points limit both the maximum pumping rate and the allowed saltwater intrusion limit. The equation is presented in the form of design curves from which the maximum pumping rate can be read off quickly. The equation and the design curves are suitable for preliminary estimation of available groundwater resources in coastal areas.

• Journal of Soil and Groundwater Environment
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• v.24 no.2
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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.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.260-264
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• 2005

Effective use of water resources has become a social problem because the deficit of water comes from population growth and Industrial development. Therefore, the conjunctive operation of surface water and groundwater will become an alternative. Groundwater has many advantages for the evaporation and effect of rainfall compared with surface water. Although the available amount of groundwater is small, groundwater dam can be used complementarily because of the sustainable supply of water. A calculating technique of the optimal amount of water resources by the groundwater dam was developed. A pilot site was selected to assess the optial amount of groungwater for the designed groungwater dam. If the developed technique is more refined by the measured data, the groundwater dam will become a good alternative to develope the water resources in the water deficit area.

• Journal of Soil and Groundwater Environment
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• v.20 no.7
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• pp.23-33
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• 2015

This study was conducted to provide the preliminary data on preparation for policy decisions regarding the groundwater supply scheme for N. Korea vulnerable to drought. Agricultural activities oriented to upland field due to the mountainous terrain more than 79% as well as the diversity of rainfall distribution over the country make more vulnerable to structural problems in the drought in N. Korea. Therefore, in anticipation of the expansion of exchange policies in agricultural sector, the available amount of groundwater needed for sustainable water resources supply was estimated for each administrative district after analyzing alluvium and hydrogeology distribution in N. Korea. Overall, the available amount of groundwater was estimated to 22.3 billion m³ (0.18 million m³/km²). The available amount of groundwater per unit area in Ryanggangdo and Gaesungsi was appeared very high in each of 0.56 and 0.39 million m³/km², respectively, and it would be interpreted that two districts have relatively wide area of volcanic rocks and alluvium with highly permeable characteristics, respectively. Finally, to maximize the utilization of this study result, the available amount of groundwater distribution map was developed on the basis of the 1 × 1 km grid network over the entire N. Korea.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.182-182
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• 2017

Many small island nations rely on groundwater as their only other source of freshwater in addition to rainwater harvesting. The volume of groundwater resource of small island nations are further limited by their smaller surface area and specific hydrogeology. The rapid growth of population and tourism has led to increasing water demands and pollution of available groundwater resources. The predicted climate change effects pose significant threats to the already vulnerable freshwater lens of small islands in the form of rise in sea level, coastal inundation, saltwater intrusion, varied pattern of precipitation leading to droughts and storm surges. The effects of climate change are further aggravated by manmade stresses like increased pumping. Thus small island water resources are highly threatened under the effects of climate change. But due to the limited technical and financial capacity most of the small island developing states were unable to conduct detailed technical investigations on the effects of climate change on their water resources. In this study, we investigate how well small island countries are preparing for climate change. The current state of freshwater resources, impacts of predicted climate change along with adaptation and management strategies planned and implemented by small island countries are reviewed. Proper assessment and management practices can aid in sustaining the groundwater resources of small islands under climate change.

• Journal of Environmental Science International
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• v.33 no.7
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• pp.511-522
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• 2024

The optimal yield is defined as the amount of groundwater that maintains a dynamic equilibrium state of the groundwater system over a long period. We examined the current problems, improvements, and methods for estimating the optimal groundwater yield in Korea, considering sustainable groundwater development. The optimal yield for individual wells and the sustainable yield for the entire groundwater basin were reviewed. Generally, the optimal yield for individual wells can be determined using long-term pumping and step drawdown tests. The optimal yield can be determined by groundwater quantity and quality, economic, and water use rights factors. The optimal yield of individual wells in the groundwater basin must be determined within the total sustainable amount of the entire groundwater basin, such that the optimal yield of a new well must be less than the remaining total sustainable amount, exempting the total optimal yield of the existing wells. Therefore, the optimal yield may be determined based on the estimated optimal yield at least twice per year. In addition, if groundwater level and pumping quantity data for at least one year are available, it may be effective to use the Hill, Harding, and zero groundwater-level change methods to re-estimate the optimal yield.

• Economic and Environmental Geology
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• v.44 no.6
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• pp.525-532
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• 2011

In this study, the usefulness of underground dam as a means for the sustainable development of groundwater, and its performance in the management of groundwater resources were analyzed. The fully integrated SWAT-MODFLOW was applied to the Ssangcheon watershed in Korea to evaluate the effectiveness of groundwater dam construction. After construction, the groundwater level raised in the upstream area of groundwater dam while lowered in the downstream area. Also, it is shown that the exchange rate of river-aquifer interactions increased in the upper area of the dam. Since the storage capacity of the aquifer largely increased in the upper area of the dam, the exploitable groundwater could be greatly increased as much. This study demonstrated that a groundwater dam was a very useful measure to increase the available storativity of groundwater aquifers. It also represented that the combined analysis using SWAT-MODFLOW was helpful for the design and opeation of groundwater dam in the Ssangcheon watershed.

• Journal of Soil and Groundwater Environment
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• v.26 no.5
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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.

• Journal of the Korean earth science society
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• v.43 no.4
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• pp.481-489
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• 2022

Various types of karst topographies are found worldwide. Owing to their global distribution, karst areas have been extensively studied by scientists who investigate new discoveries by linking the characteristics of karst topographies with their own research fields. However, there have been only a few studies on karsts in the Republic of Korea, and little research exists on their hydrogeology. Fragmentary studies have been conducted on the hydrochemical characteristics of groundwater in limestone areas, the causes of high arsenic concentrations in groundwater, and the hydraulic conductivity of limestone areas. Research on hydrogeological characterization and flow mechanisms in these areas has only began recently. Identification and the proper management of available groundwater resources in karst (limestone) areas is essential as their unique geological characteristics render it difficult to construct reservoirs or dams at appropriate scales. We have reviewed prior work on karsts in the Republic of Korea to provide information that supports water resource security in the karst areas, to improve the understanding of the equitable use of water resources, and to identify the best management practices for groundwater resource resilience improvement.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.389-394
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• 2008

The purpose of this research was to develop a methodology to determine whether conjunctive surface water and groundwater management could significantly reduce deficits in a river basin with a relatively limited alluvial aquifer. The Geum River basin is one of major river basins in South Korea. The upper region of the Geum River basin is typical of many river basins in Korea where the shape of river basin is narrow with small alluvial aquifer depths from 10m to 20m and where most of the groundwater pumped comes quickly from the steamflow. The basin has two surface reservoirs, Daecheong and Yongdam. The most recent reservoir, Yongdam, provides water to a trans-basin diversion, and therefore reduces the water resources available in the Geum River basin. After the completion of Yongdam reservoir, the reduced water supply in the Geum basin resulted in increasing conflicts between downstream water needs and required instream flows, particularly during the low flow season. Historically, the operation of groundwater pumping has had limited control and is administered separately from surface water diversions. Given the limited size of the alluvial aquifer, it is apparent that groundwater pumping is essentially taking its water from the stream. Therefore, the operation of the surface water withdrawals and groundwater pumping must be considered together. The major component of the conjunction water management in this study is a goal-programmin g based optimization model that simultaneously considers surface water withdrawals, groundwater pumping and instream flow requirements. A 10-day time step is used in the model. The interactions between groundwater pumping and the stream are handled through the use of response and lag coefficients. The impacts of pumping on streamflow are considered for multiple time periods. The model is formulated as a linear goal-programming problem that is solved with the commercial LINGO optimization software package.