• Journal of Soil and Groundwater Environment
• /
• v.28 no.2
• /
• pp.1-11
• /
• 2023

Groundwater-surface water interaction was evaluated using water quality parameters (temperature and electrical conductivity), distributions of stable water isotopes (δ²H and δ ¹⁸O), and Rn-222 in lagoon water, groundwater, and seawater at three coastal lagoons (Songji (SJ), Youngrang (YR), and Sunpo (SP) Lagoon) in South Korea. From the results of composition and distributions of δ²H and δ¹⁸O, it was found that groundwater fraction of lagoon water in YR Lagoon (76%) was slightly higher than those of SJ (42%), and SP (63%) Lagoon. Based on Rn-222 mass balance model, groundwater discharge into SJ Lagoon in summer 2020 was estimated to be (3.2±1.1)×10³ m³ day^-1, which showed a similar or an order of magnitude higher than the results of previous studies conducted in coastal lagoons. This study can provide advanced techniques to evaluate groundwater-surface water interaction in coastal lagoons, wetlands, and lakes, and help to determine the effects of groundwater on coastal ecosystems.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2003.04a
• /
• pp.418-421
• /
• 2003

Surfactant enhanced in-situ soil flushing was peformed to remediate the soil and groundwater at an oil contaminated site, and the effluent solution was treated by the chemical treatment process including DAF(Dissolved Air Flotation). A section from the contaminated site(4.5m$\times$4.5m$\times$6.0m) was selected for the research, which was composed of heterogeneous sandy and silt-sandy soils with average Hydraulic conductivity of 2.0$\times$10$^{-4}$ cm/sec. Two percent of sorbitan monooleate(POE 20) and 0.07% of iso-prophyl alcohol were mixed for the surfactant solution and 3 pore volumes of surfactant solution were injected to remove oil from the contaminant section. Four injection wells and two extraction wells were built in the section to flush surfactant solution. Water samples taken from extraction wells and the storage tank were analyzed by GC(gas-chromatography) for TPH concentration with different time. Five pore volumes of solution were extracted while TPH concentration in soil and groundwater at the section were below the Waste Water Discharge Limit(WWDL). Total 18.5kg of oil (TPH) was removed from the section. The concentration of heavy metals in the effluent solution also increased with the increase of TPH concentration, suggesting that the surfactant enhanced in-situ flushing be available to remove not only oil but heavy metals from contaminated sites. Results suggest that in-situ soil flushing and chemical treatment process including DAF could be a successful process to remediate contaminated sites distributed in Korea.

• Journal of Korea Water Resources Association
• /
• v.37 no.6
• /
• pp.509-515
• /
• 2004

In this study, comprehensive evaluation on the fully coupled SWAT-MODFLOW model is performed. Since combined model can consider the spatially varied daily recharge rate, groundwater modeling would be greatly enhanced. Also, combined model has been able to generate the distribution of groundwater heads with time, surface-subsurface flow modeling would be greatly advanced. River-aquifer interaction is well established in the combined model considering two-way interactions. Consequently, the reliability of groundwater discharge and total runoff of watershed would be greatly enhanced when combined model is used.

• Journal of Korean Society of Water and Wastewater
• /
• v.35 no.6
• /
• pp.497-505
• /
• 2021

This paper investigates the current status of Jeju special self-governing province (JSSGP)'s water infrastructure and recommends directions for improvement. JSSGP relies on groundwater for most of its water resources. Recently, water usage has been steadily increasing due to the increase of residents and tourists while the quality of groundwater has been steadily worsening. Deterioration in water quality of groundwater can be seen through the increase in concentration of nitrate nitrogen and microorganisms. To overcome such problems, water consumption must be reduced by water demand management in all fields including residential and agricultural water use. The quality of water resources should be preserved through the management of pollutants. For efficient management of water resources, great efforts should be made to reduce the leakage rates in household and agricultural water, which is currently at the highest level in the country. Furthermore, diversification of water intake sources other than groundwater is needed, especially for agricultural water supply. For water and sewerage facilities, compliance with drinking water quality standards and discharge water quality standards must be achieved through the optimization of operation management. This process requires recruiting professionals, improving existing workers' expertise, and improving facilities.

• Journal of Soil and Groundwater Environment
• /
• v.14 no.5
• /
• pp.29-40
• /
• 2009

In general, understanding groundwater flow in fractured bedrock is critical during tunnel and underground cavern construction. In that case, borehole data may be useful to examine groundwater flow properties of the fractured bedrock from pre-excavation until completion stages, yet sufficient borehole data is not often available to acquire. This study evaluated groundwater discharge rate into Jikri tunnel in Gyeonggi province using hydraulic parameters, groundwater level data in the later stage of tunneling, national groundwater monitoring network data, and electrical resistivity survey data. Groundwater flow rate into the tunnel by means of analytical method was estimated $7.12-74.4\;m^3/day/m$ while the groundwater flow rate was determined as $64.8\;m^3/day/m$ by means of numerical modeling. The estimated values provided by the numerical modeling may be more logical than those of the analytical method because the numerical modeling could take into account spatial variation of hydraulic parameters that was not possible by using the analytical method. Transient modeling for a period of one year from the tunnel completion resulted in the recovery of pre-excavation groundwater level.

• Korean Journal of Remote Sensing
• /
• v.37 no.6_1
• /
• pp.1589-1597
• /
• 2021

Submarine groundwater discharge (SGD) in coastal areas is gaining importance as a major transport route that bring nutrients and trace metals into the ocean. This paper describes the analysis of the seasonal changes and spatiotemporal characteristicsthrough the modeling monthly SGD for 35 years from 1986 to 2020 for the Nakdong river basin. In this study, we extracted 210 watersheds and SGD estimation points using the SRTM (Shuttle Radar Topography Mission) DEM (Digital Elevation Model). The average annual SGD of the Nakdong River basin was estimated to be 466.7 m²/yr from the FLDAS (Famine Early Warning Systems Network Land Data Assimilation System) recharge data of 10 km which is the highest resolution global model applicable to Korea. There was no significant time-series variation of SGD in the Nakdong river basin, but the concentrated period of SGD was expanded from summer to autumn. In addition, it was confirmed that there is a large amount of SGD regardless of the season in coastal area nearby large rivers, and the trend has slightly increased since the 1980s. The characteristics are considered to be related to the change in the major precipitation period in the study area, and spatially it is due to the high baseflow-groundwater in the vicinity of large rivers. This study is a precedentstudy that presents a modeling technique to explore the characteristics of SGD in Korea, and is expected to be useful as foundational information for coastal management and evaluating the impact of SGD to the ocean.

• Journal of Korea Water Resources Association
• /
• v.55 no.12
• /
• pp.1011-1020
• /
• 2022

Previous studies for the assessment of submarine groundwater discharge (SGD) were perfomed for areas where a large amount of SGD was observed. Newly developed assessment methods were proposed that was based on an analytic solution using sharp interface model. The proposed mathematical equations used the existing observed groundwater level and hydrogeological data of Jeju Island as input data. The quantitatively assessed FSGD values were compared to the basin-scale recharge estimation values in Seong-San area in eastern Jeju. As a result of the study, it was estimated that the amount of FSGD in the Seongsan area ranges from about 2.65 to 9.15% of the amount of areal-recharge. Through the analysis of the FSGD combined with the analytic model, it is to be provided as a scientific tool to establish a more reasonable coastal water resource management plan.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.4 no.3
• /
• pp.38-48
• /
• 2001

A wetland is an ecosystem which is the most useful and highly-energetic transition area. This study has been carried out to develop the wetland function assessment methods and apply on the natural wetlands (Mul-young-ari wetland in Jeju-island and Bangdong wetland in Taejon Metropolitan city) using RAM (Rapid Assessment Method). The RAM is useful method for assessing the wetland functions in terms of general functions acquired by once or twice onsite surveying. Eight functions of 2-12 variables each are analyzed for assessing the wetland functions. The results are as follows : 1) The conservation values of two wetlands are "High". 2) In Mul-young-ari wetland, such functions as groundwater discharge, floral diversity and wildlife habitat, shoreline/stream bank protection are relatively high, but some functions such as flood/storm water storage, aesthetics and recreation are "Moderate" - "High". 3) In Bangdong wetland, such functions as floral diversity and wildlife habitat, groundwater discharge, flood/storm water storage, aesthetics and recreation are high, and another functions are "Moderate" - "High". The taxonomy of this study stems from assessing functions of inland wetlands using indices of RAM. So It is needed that consequent studies are to be performed with verifying the variables and indices.

• Journal of the Korean Society of Groundwater Environment
• /
• v.4 no.3
• /
• pp.111-115
• /
• 1997

Discrete fracture model has become one of the alternatives for the classical continuum model to simulate the irregular aspects of the fluid flow and the solute transport in fractured rocks. It is based on the assumptions that the discharge in a single fracture is proportional to the cube of the aperture and the fractured rock can be represented by the statistical assemblage of such single fractures. This study is intended to evaluate the effect of the fracture junction on the cubic law. Numerical solution of flow in junction system was obtained by using the Boundary-Fitted Coordinate System (BFCS) method. Results with different intersection angles in crossing fractures show that the geometry of the junction affects the discharge pattern under the same simulation conditions. Therefore, strict numerical and experimental examinations on this subject are required.

• Ocean and Polar Research
• /
• v.25 no.1
• /
• pp.75-87
• /
• 2003

The water balance calculation in the IRL shows that fresh groundwater discharge is the primary factor, with surface runoff from gaged and ungaged areas as the second freshwater contributor. Precipitation and evaporation are almost in balance fer the entire IRL. Due to high freshwater discharge from ground-water, the annual net flow is outward from the IRL to the continental shelf of the Atlantic Ocean resulting in a relatively short flushing time, denoted as $T_{0.5}$ (50% flushing time) and $T_{0.99}$ (99% flushing time). $T_{0.5}$, and. $T_{0.99}$ without a tidal effect in the Northern IRL are 17 and 114 days, respectively, during the dry season. During the wet season, they are 10 and 65 days, respectively. Tidal flushing effects are considered in central IRL due to the proximity to Sebastian Inlet. In the Northern Central zone during dry season, $T_{0.5}$, and. $T_{0.99}$ are 6 and 43 days, respectively and during the wet season 5 and 33 days. In the Southern Central zone they are 2 and 16 days for the dry season,2 and 15 days for the wet season. High groundwater seepage into the IRL is considered to be a positive effect in maintaining relatively good water quality condition even with few narrow inlets.