• Journal of Environmental Impact Assessment
• /
• v.12 no.3
• /
• pp.189-198
• /
• 2003

The purpose of this paper is to evaluate the groundwater pumping capadty at a catchment area containing interrelated wells without considering their qualities by using numerical simulation in Miyake Island, young volcanic island with very complicated hydro-geological formations. The groundwater pumping capadties of each well and over entire study area were estimated as the IMY(i,t) by individual withdrawals and the SSMY(t) by simultaneous withdrawals. These results can be used to secure a sure source for taking a plan for supplying water use in young volcanic island as Miyake Island. In simultaneous withdrawals, the withdrawals from well no. 5 and 6 should have the roles as the barrier wells against the intrusion of the groundwater of the part adjacent to Tairo Pond into the inner part of study area. Therefore, it can be suggested to adopt the simultaneous withdrawals as the optimal approach of groundwater management for supplying water use with respect to quantity and quality.

• Korean Journal of Agricultural Science
• /
• v.50 no.4
• /
• pp.785-798
• /
• 2023

Considering irrigation facilities are currently insufficient and drought vulnerability due to climate change is high, efficient measures are required to secure water supply for field crops. This study, therefore, calculated the water shortage to secure water for representative field crops. An economic analysis was further conducted by comparing the production income to the input cost for each method. Here, five distinct regions were selected to represent each crop-Cheongyang-gun for chili peppers, Yesan-gun for apples, Dangjin-si for cabbages, Seosan-si for garlic, and Goesan for beans. The regions with insufficient water supply were estimated by calculating the water requirements and the supplied water from public groundwater wells for each area. A comprehensive set of four scenarios was presented as a strategy to ensure water security and manage irrigation facilities. These scenarios comprised the maintenance of existing groundwater wells, the construction of new water storage tanks, the installation of additional groundwater wells, and the utilization of surface water. B/C (benefit/cost) analysis was conducted for each scenario. As a result, the construction of water storage tanks was selected as a facility and water management plan in Cheongyang-gun, Dangjin-si, and Seosan-si. The analysis additionally indicated the economic viability of installing surface water utilization facilities in Yesan-gun and developing water storage tanks and groundwater (aquifer) wells in Goesan-gun. The results of this study are considered to serve as foundation data that may be utilized in the selection of water management plans for drought-prone areas in the future.

• Journal of Soil and Groundwater Environment
• /
• v.13 no.1
• /
• pp.67-76
• /
• 2008

In this study, a combined model of a water-table fluctuation and a soil moisture content model is proposed for the estimation of groundwater recharge rate at a given location. To evaluate the model, groundwater level data from 4 monitoring wells (Pohang Yeonil, Pohang Kibuk, Suncheon Oeseo, Hongcheon Hongcheon) of National Groundwater Monitoring Network from 1996 to 2005 and precipitation data of corresponding years are used. From the proposed methodology, the groundwater recharge rates are estimated to be from 0.5 to 61.4% for Hongcheon Hongcheon, from 1.1 to 27.4% for Pohang Yeonil, from 5.1 to 41.4% for Pohang Kibuk, and from 1.1 to 8.3% for Suncheon Oeseo. The magnitude of variation of the estimated recharge rate depends on the soil type observed near the stations. The groundwater fluctuation model used in this study includes precipitation as a unique source of water-table perturbation and there may exist corollary limitations. To improve the applicability of the proposed method, a capillary-water content constitutive model for unsaturated fractured rock media may be considered. The proposed recharge rate delineation method is physically based and uses minimum numbers of assumptions. The method may be used as a better substitute for the previous tools for delineating recharge rate of a location using water-table fluctuation method and contribute to national groundwater management plan. Further research on the spatial interpolation of the method is under progress.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.38 no.4
• /
• pp.527-535
• /
• 2018

Agricultural activities of western Jeju island has suffered from saltwater intrusion seasonally. Objectives of this study are to prove the occurrence of saltwater intrusion in the coastal aquifer and to consider a management plan using MODFLOW-family code SEAWAT model. Model results show that the saltwater-freshwater interface intrudes inland only a few meters and that upconing phenomenon is rather the cause of the severe disaster of the agricultural water contamination. This study selected Gosan area as a representative site to estimate optimal groundwater development regulation against upconing by seasonal pumping for agriculture. The suggested optimal groundwater development estimation method considers the groundwater levels of representative monitoring wells for regulatory alarms.

• Journal of Soil and Groundwater Environment
• /
• v.21 no.1
• /
• pp.61-71
• /
• 2016

Visual MODFLOW was used for quantifying stream-aquifer interactions caused by seasonal groundwater pumping. A hypothetical conceptual model was assumed to represent a stream-aquifer system commonly found in Korea. The model considered a two-layered aquifer with the upper alluvium and the lower bedrock and a stream showing seasonal water level fluctuations. Our results show that seasonal variation of the stream depletion rate (SDR) as well as the groundwater depletion depends on the stream depletion factor (SDF), which is determined by aquifer parameters and the distance from the pumping well to the stream. For pumping wells with large SDF, groundwater was considerably depleted for a long time of years and the streamflow decreased throughout the whole year. The impacts of return flow were also examined by recalculating SDR with an assumed ratio of immediate irrigation return flow to the stream. Return flow over 50% of pumping rate could increase the streamflow during the period of seasonal pumping. The model also showed that SDR was affected by both the conductance between the aquifer and the stream bed and screen depths of the pumping well. Our results can be used for preliminary assessment of water budget analysis aimed to plan an integrated management of water resources in riparian areas threatened by heavy pumping.

• Journal of Soil and Groundwater Environment
• /
• v.22 no.6
• /
• pp.1-11
• /
• 2017

This study was conducted to investigate the performance of four commercial chemical agents in stabilizing arsenic (As) in soil at the forest area near the former Janghang smelter site. After amending the stabilizing agents (A, B, C, and D) into As-contaminated soil samples, synthetic precipitation leaching procedure (SPLP) and solubility bioavailability research consortium (SBRC)-extractable As concentrations significantly decreased except for agent D, which is mainly composed of fly ash and calcium carbonate. Increase of SPLP and SBRC-extractable As concentrations in four soil samples (S1, S2, S3, and J2) was attributed to desorption of As adsorbed on iron oxides due to high pH generated by agent D. It is therefore necessary to consider application conditions according to soil characteristics such as pH and buffering capacity. Results of sequential extraction showed that readily extractable fractions of As in soil (i.e., sum of $SO_4-$ and $PO_4-extractable$ As in soil) were converted into non-readily extractable fractions by amending agents A, B, and C. Such changes in the As distribution in soil resulted in the decrease of SPLP and SBRC-extractable As concentration. A series of follow-up monitoring and management plan has been suggested to assess the longevity of the stabilization treatments in the site.

• Journal of Korea Water Resources Association
• /
• v.40 no.6 s.179
• /
• pp.469-483
• /
• 2007

Nitrate and chloride are the most common contaminants in groundwater and their concentrations increase easily due to fertilizer consumption and urbanization. The number of time series data for groundwater quality at a single site was not sufficient to analyze trends on Jeju Island. Therefore rectangle grids were drawn for the whole island and single grid was determined to be $500m{\times}500m$ after considering similar stream density, homogeneous hydraulic coefficients, geologic features of volcanic rock and low topographic slopes. All data within each lattice were collected and arranged in time series order and analyzed using Sen's method. 10.6 % of the total lattices for chloride and 22.4% for nitrate showed upward trends from the early 1990's to the early 2000's. Especially, upward trends for nitrate concentration are distinct in the low mid-mountainous areas of western and southern watersheds. Many septic tanks and much domestic waste from the urbanization of the low mid-mountainous area have produced this upward trend. Additionally, the agricultural region has dramatically increased since the 1990's and this has led to an increase of fertilizer consumption and, as a result, nitrate concentration. Therefore, the target of any management plan for groundwater quality on Jeiu Island needs to be focused on careful land use decisions in the mid-mountainous areas which are near Halla Mountain.

• Journal of the Korean Society of Groundwater Environment
• /
• v.4 no.1
• /
• pp.5-13
• /
• 1997

The Island of Cheju plans massive ground water development to meet predicted water demand. Effective management of ground water resources requires impact assessment study. Due to the nature of the island, effects of sea water must be considered. In this work, salt water intrusion, due to hypothetical ground water development in Eastern and Central Cheju Watersheds, is predicted using a sharp-interface model. The model considers simultaneously hydrodynamics of both freshwater and saltwater. The hypothetical ground water development was designed such that it follows closely the regional ground water development plan. The numerical model predicted that the saltwater wedge may intude over 1km depending on the location. This observation leaves doubt on impact assement studies based on freshwater-flow only modeling.

• Journal of Environmental Impact Assessment
• /
• v.22 no.4
• /
• pp.345-359
• /
• 2013

The Ministry of Environment established a plan for advancement of livestock manure management in July 2011 and finalized the "Comprehensive Measures for Advancement of Livestock Manure Management" in May 2012 complementing and strengthening the plan. In this process, it was necessary to investigate the status of discharge of livestock manure and its environmental impact, for example on rivers, groundwater, arable outflow water and soil. We investigated types of livestock husbandry, discharge of livestock manure, and production and use of organic fertilizers and presented the improvement measures of livestock manure management and organic fertilizer use. First, it is necessary to come up with measures to calculate appropriate density and numbers of livestock animals and prevent overcrowded breeding. Second, as many of the private livestock manure treatment facilities are out-dated and their long-term aerated reaction tanks are not regularly managed, it is necessary to find ways to improve those facilities through inspection and diagnosis. In addition, since existing public treatment facilities are designed to add clean water to belt filter press, additional water is needed. Therefore, it is necessary to improve belt filter press in order to decrease the extra water. Finally, although large-scale organic fertilizer plants and resources recycling centers produce good organic (liquid) fertilizers with proper components, it is necessary to establish standards for maturity of liquid fertilizers in order to facilitate efforts to turn livestock manure into resources.

• Journal of Soil and Groundwater Environment
• /
• v.29 no.1
• /
• pp.39-50
• /
• 2024

Slags from steel-making industry have been recycled at a target rate of 95% and most of them are recycled as media-contact type such as fill and cover materials in Korea. However, as they contain free phase CaO during their generation, they may not only expand and collapse upon contact with water, but high pH leachate and heavy metals leaching may occur. In this study, the Korean leaching procedure (KLP) and up-flow percolation test were performed for the samples collected from 17 steel-making production plants in Korea. The waste quality criteria were met in all tests, but pH of the samples was above 10. There are no regulations on the pH of leachate in most of the countries, however, Germany, Italy, and Australia have set a pH range of 10 to 13 for the leachates. Although slag leachate cannot be considered hazardous based only on its high pH, it is necessary to reduce the pH of leachate to minimize the impact on the surrounding environment. Furthermore, conflicting regulations on wastes handling and management in Korea created confusion on the types of wastes subject to recycling. Therefore, an appropriate management plan for steel-making slags needs to be established. To this end, this study attempted to provide a guideline for managing steel-making slag waste by considering international guidelines and current management practices in Korea.