• Journal of Soil and Groundwater Environment
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• v.16 no.6
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• pp.66-78
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• 2011

It is getting difficult to manage water resources in South Korea because more than half of annual precipitation is concentrated in the summer season and its intensity is increasing due to global warming and climate change. Artificial recharge schemes such as well recharge of surface water and roof-top rainwater harvesting can be a useful method to manage water resources in Korea. In this study, potential artificial recharge site is evaluated using geographic information system with hydrogeological and social factors. The hydrogeological factors include annual precipitation, geological classification based on geological map, specific capacity and depth to water level of national groundwater monitoring wells. These factors were selected to evaluate potential artificial recharge site because annual precipitation is closely related to source water availability for artificial recharge, geological features and specific capacity are related to injection capacity and depth to water is related to storage capacity of the subsurface medium. In addition to those hydrogeological factors, social aspect was taken into consideration by selecting the areas that is not serviced by national water works and have been suffered from drought. These factors are graded into five rates and integrated together in the GIS system resulting in spatial distribution of artificial recharge potential. Cheongsong, Yeongdeok in Gyeongsangbuk-do and Hadong in Gyeongsangnam-do, and Suncheon in Jeollanam-do were proven as favorable areas for applying artificial recharge schemes. Although the potential map for artificial recharge in South Korea developed in this study need to be improved by using other scientific factors such as evaporation and topographical features, and other social factors such as water-curtain cultivation area, hot spring resorts and industrial area where groundwater level is severely lowered, it can be used in a rough site-selection, preliminary and/or feasibility study for artificial recharge.

• Journal of Environmental Impact Assessment
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• v.4 no.1
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• pp.17-23
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• 1995

To assess preliminarily the contamination potential of water resources including groundwater owing to the hydrogeological characteristics of landfill site and the potential impact to humans and animals through contamination of water resources by leachate, "Landfill Site Preliminary Assessment Model(LASPAS)" was contrived. LASPAS could help them proritization of remediation of landfil sites by the convenient and relatively simple evaluation method of landfill site features. LASPAS was designd to aliot numerical ratings to landfill site related factors undermentioned; 1) hydrogeological factors such as hydraulic conductivity of aquifer, thickness of confining layer over aquifer, topographical slope, net recharge, and subsurface containment 2) water resources contamination factors of impacts on receptors such as proximity to drinking water supply, substitutability of drinking water supply, type of use of water resources, known impact on drinking water supply, and flood potential.

• Economic and Environmental Geology
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• v.35 no.5
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• pp.479-490
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• 2002

The aim of this study is to evaluate the contributions of each hydrogeological factors to groundwater recharge ratios in order to determine areal estimates of recharges in entire inland area of South Korea. For this purpose, various statistical analyses and overlay techniques of GIS were conducted fur entire area and 4 river basins of South Korea. As a result, the spatial distribution of recharge, South Korea were visualized.

• Geomechanics and Engineering
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• v.36 no.5
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• pp.441-453
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• 2024

Sinkhole subsidence and collapse is a common geohazard often formed in karst areas such as the state of Florida, United States of America. To predict the sinkhole occurrence, we need to understand the formation mechanism of sinkhole and its karst hydrogeology. For this purpose, investigating the factors affecting sinkholes is an essential and important step. The main objectives of the presenting study are (1) the development of a machine learning (ML)-based model, namely C5.0 decision tree (C5.0 DT), for the prediction of sinkhole susceptibility, which accounts for sinkhole/subsidence inventory and sinkhole contributing factors (e.g., geological/hydrogeological) and (2) the construction of a regional-scale sinkhole susceptibility map. The study area is east central Florida (ECF) where a cover-collapse type is commonly reported. The C5.0 DT algorithm was used to account for twelve (12) identified hydrogeological factors. In this study, a total of 1,113 sinkholes in ECF were identified and the dataset was then randomly divided into 70% and 30% subsets for training and testing, respectively. The performance of the sinkhole susceptibility model was evaluated using a receiver operating characteristic (ROC) curve, particularly the area under the curve (AUC). The C5.0 model showed a high prediction accuracy of 83.52%. It is concluded that a decision tree is a promising tool and classifier for spatial prediction of karst sinkholes and subsidence in the ECF area.

• Journal of the Korean GEO-environmental Society
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• v.12 no.12
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• pp.13-20
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• 2011

The main objective of this paper is finding the influence factors and their degree of importance to steel liner's safety by investigating and evaluating the buckling incidents of steel tunnel liner under external water pressure. The study was based on the detailed investigation to the design conditions and incident shapes at 2m diameter waterway tunnel with a partially buckled internal steel liner and concrete backfilled lining as the raw water transmission pipe line of regional water supply project. Appropriate buckling theory capable of applying this incident points was selected by referring the existing literature and compared with the results of investigation. Also, hydrogeological characteristics of this site on buckling pressure was evaluated. The result of this study was shown that both the hydrogeological characteristics of upper geologic layers and proper tunnel construction are important factors on buckling at steel liner, and hydraulic gradient level should be decided according to the hydrogeological characteristics. This incident case analysis on steel liner of pressurized waterway tunnel was expected to provide more information for realizing the problems and improvements at each design, construction and maintenance stages.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.09a
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• pp.155-159
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• 2001

A study on multivariate statistical classification of ground water hydrographs was conducted. The vast data of national ground water monitoring network (78 sites of alluvium) were used. 6 factors were selected to classify the ground water level change. Factor analysis was proved to be useful tool for classifying vast hydrogeological data.

• Spatial Information Research
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• v.4 no.1
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• pp.1-11
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• 1996

DRASTIC system developed by U.S.EPA, is widely used for assessing groundwater pollution potential The system can be applied to site selection of well or waste disposal, Ianduse planning for groundwater protection, and monitoring. In this study, GIS(Geographic Information System) was established hydrogeological database of DRASTIC system and cartographic modeling to asre:; regional groundwater pollution potential around Chungju Lake. Hydrogeological factors of the system were depth to water, net recharge, aquifer media, soil media, slope and hydraulic conductivity. Risk of groundwater pollution to non -point source pollution, was also analyzed by incorporation of actual pollution sources(N, P) and DRASTIC system. The GIS data could be very quickly analysed hydrogeological characteristics of the study area by graphic user interface programs devel¬oped with AML(ARC Macro Language) of ARC/INFO.

• The Journal of Engineering Geology
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• v.11 no.1
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• pp.37-50
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• 2001

Through the modeting study on the groundwater now system around the underground stockpile site of crude oil near Seoul, we carried out the research on the influence of the groundwater yield near the site, the effect of the water curtain construction in order to reduce the influence of water yield, and the realized case study by measuring the water level change after the construction of the water curtain. For the simu1ation of the water yield and the water curtain, the nwnerical analysis code, MODFLOW has been utilized. Groundwater levels of the observation wells which were established to observe the hydraulic head around underground oil storage cavern of the study area have been changed in the range of from EL.+30 to +60 meter, while the simulation study revealed that groundwater levels changed in the range of from EL.+20 to +5Om. The hydrogeological condition of the underground oil storage cavern becomes stable by injection water to maintain the groundwater level around the cavern. The result shows the proper input of the hydrogeological factors helps the management to be effective for the oil stockpile site.

• Journal of Soil and Groundwater Environment
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• v.18 no.5
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• pp.26-38
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• 2013

In this study, priority for groundwater contamination management was assessed based on regional vulnerability in Goyang-si area, Gyonggi-do, Korea using analytic hierarchy process (AHP) and geographic information system (GIS). We proposed a concept for regional vulnerability to groundwater contamination with using socio-environmental vulnerability factors, which can be classified into three properties including regional hydrogeological property, contamination property, and groundwater use property. This concept is applied to Goyang-si area. For AHP analysis, an expertise-targeted survey was conducted. Based on the survey, a total of 10 factors (criteria) and corresponding weights for regional vulnerability assessment were determined. The result shows that regional contamination property is the most weighted factor among the three property groups (hydrogeological property: contamination property: groundwater use property = 0.3: 0.4: 0.3). Then, database layers for those factors were constructed, and regional vulnerability to groundwater contamination was assessed by weighted superposition using GIS. Results show that estimated regional vulnerability score is ranged from 22.7 to 94.5. Central and western areas of Goyang-si which have groundwater tables at shallow depths and are mainly occupied by industrial and residential areas are estimated to be relatively highly vulnerable to groundwater contamination. Based on assessed regional vulnerability, we classified areas into 4 categories. Category 1 areas, which are ranked at the top 25% of vulnerability score, take about 2.8% area in Goyang-si and give a high priority for groundwater contamination management. The results can provide useful information when the groundwater management authority decide which areas should be inspected with a high priority for efficient contamination management.

• Journal of the Korean Society of Groundwater Environment
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• v.6 no.1
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• pp.33-41
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• 1999

Time-lag and amplitudes of the fluctuation of groundwater level are used to determine hydraulic parameters around Han River. The groundwater level at observation wells fluctuates between highest and lowest responding to the Han River level. The factors affecting the groundwater fluctuation are examined. The transmisivity of the Han River alluvium calculated from the measured water table fluctuations measured ranges from 9.39${\times}$10$^1$to 4.02${\times}$10$^3$㎡/day. Based on the hydrogeological data along the river sides, the flow characteristics of groundwater for water level fluctuations were simulated using a ground water flow model MODFLOW.