• Journal of the Korean earth science society
• /
• v.43 no.4
• /
• pp.539-556
• /
• 2022

In the coastal areas of Jeju Island, composed of volcanic rocks, saltwater intrusion occurs due to excessive pumping and geological characteristics. Groundwater level and electrical conductivity (EC) in multi-depth monitoring wells in coastal areas were characterized from 2005 to 2019. During the period of the lowest monthly precipitation, from November 2017 until February 2018, groundwater level decreased by 0.32-0.91 m. During the period of the highest monthly precipitation, from September 2019 until October 2019, groundwater level increased by 0.46-2.95 m. Groundwater level fluctuation between the dry and wet seasons ranged from 0.79 to 3.73 m (average 1.82 m) in the eastern area, from 0.47 to 6.57 m (average 2.55 m) in the western area, from 0.77 to 8.59 m (average 3.53 m) in the southern area, and from 1.06 to 12.36 m (average 5.92 m) in the northern area. In 2013, when the area experienced decreased annual precipitation, at some monitoring wells in the western area, the groundwater level decreased due to excessive groundwater pumping and saltwater intrusion. Based on EC values of 10,000 ㎲/cm or more, saltwater intrusion from the coastline was 10.2 km in the eastern area, 4.1 km in the western area, 5.8 km in the southern area, and 5.7 km in the northern area. Autocorrelation analysis of groundwater level revealed that the arithmetic mean of delay time was 0.43 months in the eastern area, 0.87 months in the northern area, 10.93 months in the southern area, and 17.02 months in the western area. Although a few monitoring wells were strongly influenced by nearby pumping wells, the cross-correlation function of the groundwater level was the highest with precipitation in most wells. The seasonal autoregressive integrated moving average model indicated that the groundwater level will decrease in most wells in the western area and decrease or increase in different wells in the eastern area.

• Journal of the Korean earth science society
• /
• v.41 no.4
• /
• pp.381-390
• /
• 2020

When a radial collector well is installed and operated for agricultural purposes, negative impacts may be observed over time due to the clogging of horizontal arms, such as reduced groundwater discharge and water quality deterioration. When radial collector well No. 2 was rehabilitated using the high-pressure impulse generation technique, the specific capacity and transmissivity were increased by 43.1 and 100.6%, respectively. In contrast, according to air surging, the specific capacity and transmissivity increased by 33.8 and 85.8%, respectively, compared to the initial rate before rehabilitation. During the operation of radial collector wells since construction, the time of well rehabilitation can be effectively determined by continuously monitoring the groundwater level and pumping rate of the radial collector wells, thereby preventing a decrease in productivity.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.65 no.2
• /
• pp.1-11
• /
• 2023

This study analyzed the impact of greenhouse cultivation area and groundwater level changes due to the water curtain cultivation in the greenhouse complexes. The groundwater observation data in the Miryang study area were used and classified into greenhouse and field cultivation areas to compare the groundwater impact of water curtain cultivation in the greenhouse complex. We identified the characteristics of the groundwater time series data by the terrain of the study area and selected the optimal model through time series analysis. We analyzed the time series data for each terrain's two representative groundwater observation wells. The Seasonal ARIMA model was chosen as the optimal model for riverside well, and for plain and mountain well, the ARIMA model and Seasonal ARIMA model were selected as the optimal model. A suitable prediction model is not limited to one model due to a change in a groundwater level fluctuation pattern caused by a surrounding environment change but may change over time. Therefore, it is necessary to periodically check and revise the optimal model rather than continuously applying one selected ARIMA model. Groundwater forecasting results through time series analysis can be used for sustainable groundwater resource management.

• Journal of Soil and Groundwater Environment
• /
• v.15 no.2
• /
• pp.18-23
• /
• 2010

Usability of soil quality monitoring network for ascertaining soil quality changes was evaluated by analysing soil quality monitoring results. Tolerance limits of soil quality monitoring results from 1997 to 2007 were calculated and compared with Korean soil quality standards. This study determined that soil quality was changed if the upper 95% tolerance limit value was greater than the soil quality standard. Fluoride most frequently exceeded the soil quality standard and nickel, zinc, arsenic, copper, lead and cadmium were followed. Analysis on land use showed that tolerance limits of industrial land use most frequently exceeded the soil quality standards and residential, road and various land uses then frequently exceeded. Tolerance limits of land uses expecting high contaminant loads frequently exceeded the soil quality standards. This fact imply that the soil quality monitoring network generates reasonable data to represent change in Korean soil quality. This study also suggested that representative sampling from well identified points should be done to improve data reliability and accurately ascertain soil quality changes.

• Journal of Soil and Groundwater Environment
• /
• v.20 no.1
• /
• pp.65-75
• /
• 2015

An artificial recharge test aimed at investigating transport characteristics of the injected water plume in a fractured rock aquifer was conducted. The test used an injection well for injecting tap water whose temperature and electrical conductivity were different from the groundwater. Temporal and depth-wise variation of temperature and electrical conductivity was monitored in both the injection well and a nearby observation well. A highly permeable fracture zone acting as the major pathway of groundwater flow was distinctively revealed in the monitoring data. A finite element subsurface flow and transport simulator (FEFLOW) was used to investigate sensitivity of the transport process to associated aquifer parameters. Simulated results showed that aperture thickness of the fracture and the hydraulic gradient of groundwater highly affected spatio-temporal variation of temperature and electrical conductivity of the injected water plume. The study suggests that artificial recharge of colder water in a fractured rock aquifer could create a thermal plume persistent over a long period of time depending on hydro-thermal properties of the aquifer as well as the amount of injected water.

• 한국지구물리탐사학회:학술대회논문집
• /
• 2009.10a
• /
• pp.119-123
• /
• 2009

Gravity changes due to variations of groundwater level were measured at a ground water monitoring well, which is located at Kum-san, Korea, from November 2008 to September 2009 using Portable Earth Tide (PET) gravimeter. Groundwater level was monitored simultaneously with gravity observations. To extract gravity information from groundwater, we reduced gravity effect from atmospheric surface pressure, earth tides and its loading effect, polar motion and meter drift. In addition, in June 4, 2009, there was a pumping test at he observation well, and groundwater level and gravity variations were observed together successfully. Observation of gravity along with groundwater level is potentially useful for monitoring of aquifer water mass balance and water resources.

• Journal of the Korean earth science society
• /
• v.43 no.1
• /
• pp.165-175
• /
• 2022

Earthquakes have occurred owing to movements on a fault since several billion years ago. Research on the relationship between earthquakes and groundwater began in the 1960s in the United States, but related works, including hydrogeochemistry research, only began in the 2010s in South Korea. In this study, domestic studies on the relationship between earthquakes and groundwater until 2021 were collected from the Web of Science and characterized by subject area (groundwater level, hydrogeochemistry, combination of the two, and others). The results showed that the number of published articles per year was positively correlated with the 2011 Tohoku earthquake, 2016 Gyeongju earthquake, and 2017 Pohang earthquake, with the maximum numbers observed in 2011, 2018, 2019, and 2020. Most studies on the relationship between earthquakes and groundwater level addressed groundwater level fluctuations in the duration of the subject earthquake, with little consideration of the precursors. Groundwater level monitoring data, as well as hydrogeochemical information and microbial communities, may contribute to a more detailed understanding of groundwater flow and chemical reactions in bedrock caused by earthquakes. Therefore, the establishment of a national groundwater monitoring network for seismic monitoring and prediction is required.

• Journal of Environmental Science International
• /
• v.28 no.9
• /
• pp.737-749
• /
• 2019

In this study, the sensitivity analysis of hydraulic conductivity and separation distance (distance between injection well and pumping well) was analyzed by establishing a conceptual model considering the hydrogeologic characteristics of facility agricultural complex in Korea. In the conceptual model, natural characteristics (topography and geology, precipitation, hydraulic conductivity, etc.) and artificial characteristics (separation distance from injection well to pumping well, injection rate and pumping rate, etc.) is entered, and sensitivity analysis was performed 12 scenarios using a combination of hydraulic conductivity ($10^{-1}cm/sec$, $10^{-2}cm/sec$, $10^{-3}cm/sec$, $10^{-4}cm/sec$) and separation distance (10 m, 50 m, 100 m). Groundwater drawdown at the monitoring well was increased as the hydraulic conductivity decreased and the separation distance increased. From the regression analysis of groundwater drawdown as a hydraulic conductivity at the same separation distance, it was found that the groundwater level fluctuation of artificial recharge aquifer was dominantly influenced by hydraulic conductivity. In the condition that the hydraulic conductivity of artificial recharge aquifer was $10^{-2}cm/sec$ or more, the radius of influence of groundwater level was within 20 m, but In the condition that the hydraulic conductivity is $10^{-3}cm/sec$ or less, it is confirmed that the radius of influence of groundwater increases sharply as the separation distance increases.

• Journal of Soil and Groundwater Environment
• /
• v.20 no.4
• /
• pp.41-50
• /
• 2015

Open-loop groundwater heat pump (GWHP) system generally has benefits such as a higher coefficient of performance (COP), lower initial cost, and flexible system size. The hydrogeological conditions in Korea have the potential to facilitate the use of the GWHP system because a large number of monitoring wells show stable groundwater temperatures, shallow water levels, and high well yields. However, few studies have been performed in Korea regarding the GWHP system and the most studies among them dealt with Standing Column Well (SCW). Because the properties of the aquifer have an influence on designing open-loop systems, it is necessary to perform studies on various hydrogeological settings. In this study, the hydrogeological and thermal properties were estimated through various tests in the riverside alluvial layer where a GWHP system was installed. Under different groundwater flow velocities and pumping and injection rates, a sensitivity analysis was performed to evaluate the effect of such properties on the design of open-loop systems. The results showed that hydraulic conductivity and thermal dispersivity of the aquifer are the most sensitive parameters in terms of performance and environmental aspects, and sensitivities of the properties depend on conditions.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.65 no.6
• /
• pp.93-103
• /
• 2023

This study aimed to analyze the impact of water curtain cultivation in the greenhouse complexes on groundwater's electric conductivity and water temperature. The greenhouse complexes are mainly situated along rivers to secure water resources for water curtain cultivation. We classified the groundwater monitoring well into the greenhouse (riverside) and field cultivation areas (plain) to compare the groundwater impact of water curtain cultivation in the greenhouse complex. The groundwater observation network in Miryang, Gyeongsangnam-do, located downstream of the Nakdong River, was selected for the study area. As a result of analyzing the electric conductivity and water temperature, the following differences were found in the observed characteristics by region. 1) The electric conductivity and water temperature of the riverside area, where the permeability is high and close to rivers, showed a constant pattern of annual changes due to the influence of river flow and precipitation. 2) The flat land in general agricultural areas showed general characteristics of bedrock observation in the case of water temperature. Still, it seemed more affected by the surrounding well's water use and water quality. The electric conductivity did not show any particular trend and was influenced by the surrounding environment according to the location of each point.