• Journal of Environmental Impact Assessment
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• v.28 no.4
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• pp.373-386
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• 2019

In The study, is to investigate the spatial characteristics of the Miho stream, which is the main tributary of the Geum River system, and to identify the main factors influencing the water quality using water quality analysis and multivariate analysis. The survey subjects were selected as 7 main sites in the Miho stream water system, From 2012 to 2017, 16 items including weather temperature and weather data were used for multivariate analysis. As a result of the water quality analysis, the average concentration of BOD and COD for 6 years was 3grade (normal) compared with the water quality environmental standard (river) of conditions. The concentrations of nitrogen and phosphorus were highest at th upstream site, then decreased and then increased again by the hydrogeological and geomorphological effect. Cluster analysis of spatial and water quality characteristics, it was evaluated as three clusters and the pollution sources is the greatest impact. As a result of principal component analysis and factor analysis on each cluster and mainstream, three to four major components were extracted. Main stream and the Cluster 1, Cluster 3 first principal factor included nitrogen and seasonal factors,first factor of Cluster 2 included nitrogen and water temperature. Nitrogen is the principal factor which affects water quality in Miho stream.

• Journal of Environmental Science International
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• v.26 no.8
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• pp.939-953
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• 2017

For the development of flow duration curves for the management of 41 Total Maximum Daily Load (TMDL) units of the Nakdong River basin, first, an equation for estimating daily flow rates as well as the level of correlation (correlation and determination coefficients) was extrapolated through regression analysis of discrete (Ministry of Environment) and continuous (Ministry of Land, Infrastructure and Transportation) measurement data. The equation derived from the analysis was used to estimate daily flow rates in order to develop flow duration curves for each TMDL unit. By using the equation, the annual flow duration curves and flow curves, for the entire period and for each TMDL unit of the basin, were developed to be demonstrated in this research. Standard flow rates (abundant-, ordinary-, low- and drought flows) for major flow duration periods were calculated based on the annual flow duration curves. Then, the flow rates, based on percentile ranks of exceedance probabilities (5, 25, 50, 75, and 95%), were calculated according to the flow duration curves for the entire period and are suggested in this research. These results can be used for feasibility assessment of the set values of primary and secondary standard flow rates for each river system, which are derived from complicated models. In addition, they will also be useful for the process of implementing TMDL management, including evaluation of the target level of water purity based on load duration curves.

• Korean Journal of Environmental Biology
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• v.21 no.3
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• pp.223-233
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• 2003

This paper introduces a study on the development of environment assessment technique and biodiversity management system for stream ecosystems and their application to Korean streams. Based on comprehensive field investigations from a series of streams of Bukhangang (North Han River) system as well as on long-term field survey and bibliographic data from streams throughout South Korea, schemes for environmental and biodiversity research of stream ecosystems aye reviewed; types of major environmental damages in Korean streams are classified; a rapid assessment technique for nature quality of stream ecosystems is presented; and a list of environmental and biotic factors for the use of GIS-based biodiversity management system in stream ecosystems is provided. The biodiveysity management system, which is based on ArcView and GEUS programs, is applied to Gapyeong Creek, a typical mid-size stream in Korea.

• Journal of Korean Society on Water Environment
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• v.37 no.1
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• pp.32-46
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• 2021

South Korea has been divided into quantities and water quality, and due to a revision of the Government Organization law in June 2018, the controversial water management system was integrated into the Ministry of Environment. The total Maximum Daily Loads System has been called the flower of water quality control, and since 2004, all three major river systems which have been introduced into the Han River system, despite its various difficult environments, and subsequently leading to all of the four major rivers undergoing obligatory implementation since 2013. Currently, the target TMDL (Han River Phase 1 and Other Water Systems Phase 3) for the 2020 stage has been implemented. The domestic TMDL established a basic plan for calculating the load which complies with the unit watershed's target water quality, as well as an implementation plan for annual load management, both which have been institutionalized in order to evaluate load compliance on a repeated annual basis. Local governments ask external organizations to conduct investigations every year in order to assess the transition, which thereby requires tens of millions of won every year. Therefore, an assessment and management model that can be easily operated at the TMDL personnel level is required. In this study, when the Han river Water System TMDL was implemented in earnest, we confirmed the the water quality improvement effect when TMDL was introduced to major inflow tributaries (TancheonA, JungnangA, AnyangA) under the Seoul City's jurisdiction through the use of the total amount control unit basin evaluation technique. By presenting customized management measures, we propose the guidelines that are necessary for determining more effective water environmental policies.

• Journal of Soil and Groundwater Environment
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• v.26 no.6
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• pp.186-195
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• 2021

In Korea, groundwater quality is monitored through National Groundwater Quality Monitoring Network (NGQMN) administered by Ministry of Environment. For a given contaminant, compliance to groundwater quality standards is assessed on a annual basis by monitoring the number of incidents that concentration exceeds the regulatory limit. However, this approach provides only a fractional information about groundwater quality degradation, and more crucial information such as location and severity of the contamination cannot be obtained. For better groundwater quality management on a watershed, a more spatially informative and intuitive method is required. This study presents two statistical methods to convert point-wise monitoring data into information on groundwater quality status of a watershed by using a proposed grading scale. The proposed grading system is based on readily available reference standards that classify the water quality into 4 grades. The methods were evaluated with NO₃^-, Cl^-, and total coliform data in Geum River basin. The analyses revealed that groundwater in most watersheds of Geum River basin is good for domestic or/and drinking with no treatment. But, there was notable quality degradation in Bunam seawall and So-oak downstream standard watersheds contaminated by NO₃^- and Cl^-, respectively.

• Journal of Korean Society on Water Environment
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• v.25 no.6
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• pp.863-871
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• 2009

For the assessment of climate change impacts on river flow condition, CGCM 3.1 T63 is selected as future climate information. The projections come from CGCM used to simulate the GHG emission scenario known as A2. Air temperature and precipitation information from the GCM simulations are converted to regional scale data using the statistical downscaling method known as MSPG. Downscaled climate data from GCM are then used as the input data for the modified TANK model to generate regional runoff estimates for 44 river locations in Nakdong river basin. Climate change is expected to reduce the reliability of water supplies in the period of 2021~2030. In the period of 2051~2060, stream flow is expected to be reduced in spring season and increased in summer season. However, it should be noted that there are a lot of uncertainties in such multiple-step analysis used to convert climate information from GCM-based future climate projections into hydrologic information.

• Journal of Korean Society on Water Environment
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• v.35 no.6
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• pp.580-588
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• 2019

The flow of the middle and downstream of the Yeongsan River is stagnant by two weirs of Seungchon and Juksan and the estuary dam and maintained in freshwater. In this study, the Environmental Fluid Dynamics Code-National Institute of Environment Research(EFDC-NIER) model was applied to the Yeongsan River to simulate water flow, temperature, and salinity stratification. The EFDC-NIER model is an improved model which can simulate multi-functional weirs operation, multiple algal species, and the vertical movement mechanism of algal based on the EFDC model. The simulation results for the water level, water temperature, velocity, and salinity reproduced the observed values well. The mean absolute error(MAE) of the model calibration in the annual variations of the water level was 0.1-0.3 m, water temperature was 0.8-1.7 ℃, velocity was 4.5-7.1 cm/sec, and salinity was 1.5 psu, respectively. In the case of scenario simulation for the full opening of the estuary dam, the water level of the estuary dam was directly impacted by the tide so it was predicted to rise - 1.35 m to 0.2 m on average sea level. The velocity was also predicted to increase from 2.7 cm/sec to 50.8 cm/sec, and the flow rate to increase from 53 ㎥/sec to 5,322 ㎥/sec.

• Journal of Korean Society on Water Environment
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• v.31 no.6
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• pp.732-738
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• 2015

Water quality in four major river basin in Korea was managed with Total Maximum Daily Load (TMDL) System. The unit watershed in TMDL system has been evaluated with Target Water Quality (TWQ) assessment using average water quality, without considering its volume of water quantity. As results, although unit watershed are obtained its TWQ, its allocated loads were not satisfied and vice versa. To solve these problems, a number of TWQ assessments with using Load Duration Curve (LDC) have been studied at other watersheds. The purpose of this study was to evaluate achievement of TWQ with Flow Duration Curve (FDC) and Load Duration Curve(LDC) at 26 unit watersheds in Han river basin. The results showed that achievement rates in TWQ assessment with current method and with LDC were 50~56 % and 69~73%, respectively. Because of increasing about 20% of achievement rates with using LDC, the number of exceeded unit watershed at Han river Basin was decreased about 4~6 unit watersheds.

• Journal of Korea Water Resources Association
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• v.52 no.spc2
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• pp.765-776
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• 2019

The purpose of this study is to provide the legal and institutional guidelines and standards that can be used in the whole river restoration project and to analyze and evaluate the performance of the river project. We constructed an assessment system of four biological taxa that can represent the river environments, namely, evaluation indexes and standards of vegetation and birds, benthic invertebrates and fishes. Specifically, the assessment indicator and criteria of biological characteristics are summarized, so that in case of vegetation community, vegetation diversity, vegetation complexity, and vegetation naturalness can be quantitatively assessed through the combination of three indices. Based on the scientific basis of the advanced techniques, benthic invertebrates, fishes, and birds were proposed to quantitatively evaluate assessment grades according to the classification of biological data. In order to evaluate biological characteristics, which are a part of river environmental naturalness, we proposed a comprehensive biological index and evaluation grade applying the weight of these four biological taxa, and it clearly reflects the characteristics of river environment in test bed.

• Journal of Environmental Impact Assessment
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• v.21 no.1
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• pp.93-104
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• 2012

In this research LCA methodology was adapted and analyzed in quantifying estimation of estuarine environment. The analysed objects of estuarine environment were construction methods, facility, and input material into water, and estuarine ecosystem. In this research the function of LCA of estuarine environment was river with the view of controling water, utilizing water, and hydrophilic function. According to the result of research, environmental damage indicator of facility was decreased 346 Pt from 453 Pt at pre-maintenance to 107 pt at post-maintenance. Among raw and subsidiary materials, remicon, stone-netting bag, and pebbles were showing heavy environmental load in the order. Evironmental impact of input material into water system was analyzed from 1,827 Pt environmental load before construction to 1,080 Pt of post-maintenance, and damage indicator was improved at 747 Pt. Water quality was improved from 1,827 Pt (before construction) to 1,080 Pt(after construction), and ecosystem was improved after maintenance. Environmental indicator in ecosystem was analyzed 427 Pt(before construction) to 348 Pt(after construction), and damage indicator of Sumnjingang riverine system was improved as much as 79 Pt. In the conclusion, estuarine environmental monitoring through LCA in the area of facility, input material into water and ecosystem showed that close-to-nature stream was 1,172 Pt better than artificial stream in environmental aspects.