• The Journal of Engineering Geology
• /
• v.18 no.3
• /
• pp.263-276
• /
• 2008

In diverse hydrogeologic fields, estimation of groundwater storage change is one of the most critical issues. Accurate estimation methods for determining groundwater storage change are required more and more. For Yeonyang area of Ulsan Megacity, groundwater storage change was estimated by using water balance method and hydrogeological analyses. The estimates of groundwater storage change was 240 mm corresponding to 18.7% of mean annual precipitation. Direct runoff was calculated as 137 mm (10.6% of mean annual precipitation) by using SCS-CN method. Evapotranspiration based on the Thornthwaite method was calculated as 776 mm (60.5% of mean annual precipitation). Hydraulic properties of the soil types do not show any distinct relation with hydraulic conductivity of the rocks. This fact suggests that hydraulic property on the surface is different from that of subsurface geology. According to multi-linear regression analysis between groundwater storage change and hydraulic parameters, a regression equation of groundwater storage change, which was explained by precipitation and evapotranspiration, was established.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.18 no.3
• /
• pp.35-51
• /
• 2015

The purpose of this study is to improve the previous groundwater contamination vulnerability assessment method, apply it to the study area, and select priority areas for groundwater management based on the quantitative analysis of groundwater contamination vulnerability. For this purpose, first, the previous 'potential contamination' based on groundwater contamination vulnerability assessment method was upgraded to the methodology considering 'adaptation capacity' which reduced contamination. Second, the weight of groundwater contamination vulnerability assessment factors was calculated based on the analytical hierarchy process(AHP) and the result of survey targeting groundwater experts. Third, Gyeonggi-do was selected as the study area and the improved methodology and weight were implemented with GIS and actual groundwater contamination vulnerability assessment was carried out. Fourth, the priority area for groundwater contamination management was selected based on the quantitative groundwater contamination vulnerability assessment diagram. The improved detailed groundwater contamination vulnerability assessment factors in this study were a total of 15 factors, and 15 factors were analyzed as new and improved weight with higher 'adaptation capacity' than the assessment factor corresponding to the previous 'potential contamination' in the weight calculation result using AHP. Also, the result of groundwater contamination vulnerability assessment in Gyeonggi Province using GIS showed that Goyang and Gwangmyeong which were adjacent to Seoul had a high groundwater contamination vulnerability and Pocheon and Yangpyeong County had a relatively low groundwater contamination vulnerability. In this study, the previous groundwater contamination vulnerability assessment was improved and applied to study areas actually. The result of this study can be utilized both directly and indirectly for the groundwater management master plan at national and local government level in the future.

• Environmental Engineering Research
• /
• v.18 no.3
• /
• pp.117-121
• /
• 2013

For underpasses in Yeongjong Sky City business district, the guided drainage system, as a buoyancy prevention system has been designed, and is under construction. This paper investigates the safety of the guided drainage system for underpass structures being constructed in Yeongjong Sky City business district. This paper also calculates the amount of outflowing groundwater generated by the guided drainage system, and proposes alternative usages of the water. In order to investigate safety and field applicability of the guided drainage system for underpasses, characteristics of the surface flow for the area of interest have been analyzed, and the flow change of groundwater following the underpass structure construction has been evaluated using the 3-dimensional groundwater program MODFLOW. The influence of ground water on safety of the underpass structures has been calculated by FLAC2D analysis. For alternative usages for the outflowing groundwater generated by the guided drainage system, utilization methods of the outflowing groundwater in national and international resources have been researched. The amount of an outflowing groundwater to be generated in the area of interest has been analyzed, and efficient potential usages of this groundwater have been researched. When guided drainage technique is applied, the change in flow of groundwater must be evaluated and considered as safety factor relating to the buoyancy of the structure. As a result, safety factor demonstrated more than 1.2, meaning that the underpass structure is safe. The amount of subsoil drain generated by the guided drainage system was also analyzed. The quality and amount of water satisfied the standards and volume requirements, so as to make it applicable for a number of uses, such as X, Y, and Z, and should prove to be a valuable resource as the circumstances of the neighboring area change over time. These resources can be used as basic data for future urban water circulation studies, as well as generating research of alternative water usages.

• Journal of Soil and Groundwater Environment
• /
• v.26 no.4
• /
• pp.27-43
• /
• 2021

Since climate factors, such as precipitation, temperature, etc., show repeated patterns every year, it can be said that future changes can be predicted by analyzing past climate data. As with groundwater, seasonal variations predominate. Therefore, when a drought occurs, the groundwater level is also lowered. Thus, a change in the groundwater level can represent a drought. Like precipitation, groundwater level changes also have a high correlation with drought, so many researchers use Standard Groundwater Level Index (SGI) to which the Standard Precipitation Index (SPI) method is applied to evaluate the severity of droughts and predict drought trends. However, due to the strong interferences caused by the recent increase in groundwater use, it is difficult to represent the droughts of regions or entire watersheds by only using groundwater level change data using the SPI or SGI methods, which analyze data from one representative observation station. Therefore, if the long-term groundwater level changes of all the provinces of a watershed are analyzed, the overall trend can be shown even if there is use interference. Thus, future groundwater level changes and droughts can be more accurately predicted. Therefore, in this study, it was confirmed that the groundwater level changes in the last 5 years compared with the monthly average groundwater level changes of the monitoring wells installed before 2015 appeared similar to the drought occurrence pattern. As a result of analyzing the correlation with the water storage yields of 3,423 agricultural reservoirs that do not immediately open their sluice gates in the cases of droughts or floods, it was confirmed that the correlation was higher than 56% in the natural state. Therefore, it was concluded that it is possible to re-evaluate agricultural droughts through long-term groundwater level change analyses.

• 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 Environmental Policy
• /
• v.9 no.2
• /
• pp.157-184
• /
• 2010

Global climate change is destroying the water circulation balance by changing rates of precipitation, recharge and discharge, and evapotranspiration. The Intergovernmental Panel on Climate Change (IPCC 2007) makes "changes in rainfall pattern due to climate system changes and consequent shortage of available water resource" a high priority as the weakest part among the effects of human environment caused by future climate changes. Groundwater, which occupies a considerable portion of the world's water resources, is related to climate change via surface water such as rivers, lakes, and marshes, and "direct" interactions, being indirectly affected through recharge. Therefore, in order to quantify the effects of climate change on groundwater resources, it is necessary to not only predict the main variables of climate change but to also accurately predict the underground rainfall recharge quantity. In this paper, the authors selected a relevant climate change scenario, In this context, the authors selected A1B from the Special Report on Emission Scenario (SRES) which is distributed at Korea Meteorological Administration. By using data on temperature, rainfall, soil, and land use, the groundwater recharge rate for the research area was estimated by period and embodied as geographic information system (GIS). In order to calculate the groundwater recharge quantity, Visual HELP3 was used as main model for groundwater recharge, and the physical properties of weather, temperature, and soil layers were used as main input data. General changes to water circulation due to climate change have already been predicted. In order to systematically solve problems associated with how the groundwater resource circulation system should be reflected in future policies pertaining to groundwater resources, it may be urgent to recalculate the groundwater recharge quantity and consequent quantity for using via prediction of climate change in Korea in the future and then reflection of the results. The space-time calculation of changes to the groundwater recharge quantity in the study area may serve as a foundation to present additional measures for the improved management of domestic groundwater resources.

• Proceedings of the Korean Society of Agricultural Engineers Conference
• /
• 2003.10a
• /
• pp.311-314
• /
• 2003

This research recognized change of the specific yield(Sy) by groundwater level in small size tube well of the farm village area. The result research basin aquifer could quality that the specific yield according to geological quality of aquifer changes showed value of $0.0004{\sim}0.081$ extents according to groundwater level decline.

• Journal of Soil and Groundwater Environment
• /
• v.27 no.2
• /
• pp.36-40
• /
• 2022

To respond to rapidly changing water circumstances such as climate change, drought, etc., the korean government (MOE) established four advanced strategies for integrated groundwater management. The first strategy is watershed-based management of groundwater. The second strategy is total quantity management of groundwater including improvement of groundwater preservation area policy and procedure of investigation for groundwater influence area, additional construction of groundwater dam, installation of large-scale public wells, extention of spilled groundwater use. The third strategy is prevention of groundwater contamination including expansion of monitoring wells, introducing declaration of groundwater contamination. The last strategy is advancement of groundwater information management including integrated management of data, setting up a big-data based open platform. The above-mentioned four strategies will be reflected in the 4th National Groundwater Management Plan to secure implementation power, and it is expected to laid the foundation for advanced and rational groundwater management system.

• The Journal of the Convergence on Culture Technology
• /
• v.6 no.3
• /
• pp.369-375
• /
• 2020

The section of this study is the geological vulnerable zone where groundwater leakage occurred through the tunnel barrier during excavation of the shield tunnel boring machine(TBM) for the construction of the electric power unit. Therefore, a Three D imensions(3D) numerical analysis was performed to analyze the actual situation from before construction to the time when the change in groundwater level occurred, and to reflect the surrounding ground conditions based on the observed change in groundwater level during construction. As a result of the study, the correlation between groundwater level change and tunnel construction around the site was identified. Therefore, it was similar to the measurement result of groundwater level at the target ground. The amount of groundwater discharge to the entrance of the tunnel construction was also similar to the actual measured result, and the numerical analysis method and modeling in this study were analyzed to reflect the site conditions.

• Journal of Soil and Groundwater Environment
• /
• v.20 no.2
• /
• pp.1-9
• /
• 2015

Groundwater has been a very precious resource for human life and economic development in the world. With increasing population and food demand, the groundwater use especially for agriculture is largely elevated worldwide. The very much large groundwater use results in depletion of major aquifers, land subsidences in many large cities, anthropogenic groundwater contamination, seawater intrusion in coastal areas and accompanying severe conflicts for water security. Furthermore, with the advent of changing climate, securing freshwater supply including groundwater becomes a pressing and critical issue for sustainable societal development in every country because prediction of precipitation is more difficult, its uneven distribution is aggravating, weather extremes are more frequent, and rising sea level is also threatening the freshwater resource. Under these difficulties, can groundwater be sustaining its role as essential element for human and society in the near future? We have to focus our efforts and wisdom on answering the question. Korean government should increase its investment in securing groundwater resources for changing climate.