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Prof. Se-Woong Chung
Environmental Engineering, Chungbuk National University, Republic of Korea

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0 Climate Change
0 Water Quality Modeling
0 ecological modelling
0 Algal bloom
0 Turbidity flow

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Journal article
Published: 17 February 2021 in Science of The Total Environment
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The temporal variations in CO2 net atmospheric flux (NAF) in stratified reservoirs are controlled by both physical and biological factors. However, research on the factors and processes affecting CO2 NAF variability over time is insufficient, and as a result, there is considerable uncertainty in present estimations of global reservoir CO2 emissions. In the present study, we analyzed the effects of hydrodynamic and water quality factors on CO2 NAF variability in a stratified reservoir based on field studies and data modeling. Three empirical and four surface renewal gas transfer models were used to characterize the effects of hydrodynamic factors on gas transfer rate and CO2 NAF at the air–water interface. Buoyant turbulence notably affected CO2 NAF when the stratification strength was reduced. As a result, the CO2 NAF (1485 mg-CO2 m−2 day−1) estimated using surface renewal models that considered the effects of buoyant turbulence were twice greater than the NAFs estimated using empirical models that only considered wind force (724 mg-CO2 m−2 day−1). The best linear regression model explained 81.6% of the temporal variation in CO2 NAF using water temperature (Tw), electrical conductivity (EC), pH, chlorophyll a, total organic C (TOC), and alkalinity. The nonlinear parsimonious random forest model explained 84.4% of the temporal change in CO2 NAF using only three independent variables (EC, dissolved oxygen, and TOC). Principal component analysis revealed that the CO2 NAF tended to be large under low Tw, weak stratification, and low pH. These results indicate that the temporal variability of CO2 NAF in the stratified reservoir can be predicted using data-driven modeling with minimal water quality variables and selection of an appropriate gas exchange model. The findings improve the accuracy of estimates of CO2 emissions and monitoring activities in stratified reservoirs.

ACS Style

Hyungseok Park; Sewoong Chung; Sungjin Kim. Effect of buoyant turbulence and water quality factors on the CO2 net atmospheric flux changes in a stratified reservoir. Science of The Total Environment 2021, 776, 145940 .

AMA Style

Hyungseok Park, Sewoong Chung, Sungjin Kim. Effect of buoyant turbulence and water quality factors on the CO2 net atmospheric flux changes in a stratified reservoir. Science of The Total Environment. 2021; 776 ():145940.

Chicago/Turabian Style

Hyungseok Park; Sewoong Chung; Sungjin Kim. 2021. "Effect of buoyant turbulence and water quality factors on the CO2 net atmospheric flux changes in a stratified reservoir." Science of The Total Environment 776, no. : 145940.

Journal article
Published: 06 March 2020 in Water
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Inflow mixing affects the spatiotemporal heterogeneity of water quality in reservoirs. Reservoir water quality management requires accurate prediction of density flow regimes to understand the spatiotemporal distribution of dissolved and particulate nutrients and organics. This study aims to characterize the mixing and circulation of three rivers with different physicochemical properties in a run-of-the-river (ROR) reservoir, using high-frequency monitoring and three-dimensional (3D) hydrodynamic modeling. The Aquatic Ecosystem Model (AEM3D) was constructed for the reservoir and calibrated with high-frequency data obtained from May–June 2016, accurately reproducing the observed spatiotemporal variations of flow velocity, water temperature, and electrical conductivity (EC) in the reservoir. High-frequency data and 3D model results showed that mixing of the rivers in the ROR reservoir is governed by density flow regimes formed by influent water temperature differences. At the confluence, colder and warmer river influents formed underflows and surface buoyant overflows, respectively. The spatial arrangement of flow direction, water residence time, and EC concentration were largely controlled by the buoyancy-driven flow. Stagnant areas with long residence times corresponded with areas of observed algal blooms and hypoxia. High-frequency sensor technology, combined with 3D hydrodynamic modeling, is effective for understanding the complex flow regimes and associated water quality characteristics in ROR-type reservoirs.

ACS Style

Ingu Ryu; Soonju Yu; Sewoong Chung. Characterizing Density Flow Regimes of Three Rivers with Different Physicochemical Properties in a Run-Of-The-River Reservoir. Water 2020, 12, 717 .

AMA Style

Ingu Ryu, Soonju Yu, Sewoong Chung. Characterizing Density Flow Regimes of Three Rivers with Different Physicochemical Properties in a Run-Of-The-River Reservoir. Water. 2020; 12 (3):717.

Chicago/Turabian Style

Ingu Ryu; Soonju Yu; Sewoong Chung. 2020. "Characterizing Density Flow Regimes of Three Rivers with Different Physicochemical Properties in a Run-Of-The-River Reservoir." Water 12, no. 3: 717.

Journal article
Published: 03 June 2019 in Water
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Following the installation of 16 weirs in South Korea’s major rivers through the Four Rivers Project (2010–2012), the water residence time increased significantly. Accordingly, cyanobacterial blooms have occurred frequently, raising concerns regarding water use and the aquatic ecosystem health. This study analyzed the environmental factors associated with cyanobacterial dominance at four weirs on the Nakdong River through field measurements, and parametric and non-parametric data mining methods. The environmental factors related to cyanobacterial dominance were the seven-day cumulative rainfall (APRCP7), seven-day averaged flow (Q7day), water temperature (Temp), stratification strength (ΔT), electrical conductivity (EC), dissolved oxygen (DO), pH, and NO3–N, NH3–N, total nitrogen (TN), total phosphorous (TP), PO4–P, chlorophyll–a, Fe, total organic carbon (TOC), and SiO2 content, along with biological and chemical oxygen demands. The results indicate that site-specific environmental factors contributed to the cyanobacterial dominance for each weir. In general, the physical characteristics of EC, APRCP7, Q7day, Temp, and ΔT were the most important factors influencing cyanobacterial dominance. The EC was strongly associated with cyanobacterial dominance at the weirs because high EC indicated persistent low flow conditions. A minor correlation was obtained between nutrients and cyanobacterial dominance in all but one of the weirs. The results provide valuable information regarding the effective countermeasures against cyanobacterial overgrowth in rivers.

ACS Style

Sungjin Kim; Sewoong Chung; Hyungseok Park; Youngcheol Cho; Heesuk Lee. Analysis of Environmental Factors Associated with Cyanobacterial Dominance after River Weir Installation. Water 2019, 11, 1163 .

AMA Style

Sungjin Kim, Sewoong Chung, Hyungseok Park, Youngcheol Cho, Heesuk Lee. Analysis of Environmental Factors Associated with Cyanobacterial Dominance after River Weir Installation. Water. 2019; 11 (6):1163.

Chicago/Turabian Style

Sungjin Kim; Sewoong Chung; Hyungseok Park; Youngcheol Cho; Heesuk Lee. 2019. "Analysis of Environmental Factors Associated with Cyanobacterial Dominance after River Weir Installation." Water 11, no. 6: 1163.

Journal article
Published: 06 April 2019 in Water
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The impact of the channel geometry on water quantity and quality simulation of the Soil and Water Assessment Tool (SWAT) was evaluated for the Andong Dam watershed. The new equations to determine the bankfull width of the channels and the bottom width of the floodplains were developed using aerial photographs, and its performance was compared with the current equations of SWAT. The new equations were more exact than the current equations since the current equations tended to overestimate the widths of the channel and floodplain. When compared with the observed data, the streamflow of the scenario 2 (S2, applying the new equations) showed lower deviation and higher accuracy than scenario 1 (S1, applying the current equations) because the peak flow of S2 captured the observed data better due to the impact of the change geometry. Moreover, the water quality results of S2 outperformed S1 regarding suspended solid, total nitrogen, and dissolved oxygen. This is attributed to the variables, such as flow travel time, which is directly related to the channel geometry. Additionally, SWAT was modified to consider the various channel cross-sectional shapes. The results of this study suggest that the channel geometry information for the water quantity and quality estimation should be carefully applied, which could improve the model performance regarding streamflow and water quality simulations.

ACS Style

Jeongho Han; Dongjun Lee; Seoro Lee; Se-Woong Chung; Seong Joon Kim; Minji Park; Kyoung Jae Lim; Jonggun Kim. Evaluation of the Effect of Channel Geometry on Streamflow and Water Quality Modeling and Modification of Channel Geometry Module in SWAT: A Case Study of the Andong Dam Watershed. Water 2019, 11, 718 .

AMA Style

Jeongho Han, Dongjun Lee, Seoro Lee, Se-Woong Chung, Seong Joon Kim, Minji Park, Kyoung Jae Lim, Jonggun Kim. Evaluation of the Effect of Channel Geometry on Streamflow and Water Quality Modeling and Modification of Channel Geometry Module in SWAT: A Case Study of the Andong Dam Watershed. Water. 2019; 11 (4):718.

Chicago/Turabian Style

Jeongho Han; Dongjun Lee; Seoro Lee; Se-Woong Chung; Seong Joon Kim; Minji Park; Kyoung Jae Lim; Jonggun Kim. 2019. "Evaluation of the Effect of Channel Geometry on Streamflow and Water Quality Modeling and Modification of Channel Geometry Module in SWAT: A Case Study of the Andong Dam Watershed." Water 11, no. 4: 718.

Article
Published: 07 November 2018 in Climatic Change
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Long-term discharge of turbid water from reservoirs after flood events is a major socioenvironmental problem in many countries, including Korea. This study used a suite of mathematical models to simulate the fate of turbidity flows in the Soyanggang Reservoir in Korea, an important source of drinking water for the Seoul Capital Area, in response to extreme floods based on the Representative Concentration Pathway 4.5 climate scenario. It evaluated the effectiveness of the selective withdrawal facility (SWF), installed recently in the Soyanggang Reservoir to control persistent turbidity. Extreme floods with a maximum daily inflow rate greater than the historical maximum observed in 2006 were projected to occur four times in this century. The fate and transport of turbidity flows were highly influenced by both the thermal stability of the reservoir and the season in which the flood event occurred. Thus, SWF operations should consider the timing of extreme events (i.e., the imminence of the autumn turnover) to mitigate the impact of high turbidity on the water supply and downstream ecosystem. It was found to be ineffective under extreme events if these occurred in two consecutive years. Current reservoir operations, which rely heavily on the SWF, are likely to be inadequate to overcome the negative effects of extreme-turbidity events on reliably providing safe water supplies. Coping with the worst event expected to occur in the future would require additional countermeasures such as bypassing high-turbidity water.

ACS Style

Hyungseok Park; Sewoong Chung; Eunju Cho; Kyoungjae Lim. Impact of climate change on the persistent turbidity issue of a large dam reservoir in the temperate monsoon region. Climatic Change 2018, 151, 365 -378.

AMA Style

Hyungseok Park, Sewoong Chung, Eunju Cho, Kyoungjae Lim. Impact of climate change on the persistent turbidity issue of a large dam reservoir in the temperate monsoon region. Climatic Change. 2018; 151 (3-4):365-378.

Chicago/Turabian Style

Hyungseok Park; Sewoong Chung; Eunju Cho; Kyoungjae Lim. 2018. "Impact of climate change on the persistent turbidity issue of a large dam reservoir in the temperate monsoon region." Climatic Change 151, no. 3-4: 365-378.

Journal article
Published: 28 September 2018 in Water
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This study explores the dynamic changes in the partial pressure of CO2 (pCO2) with depth, and the temporal variations of CO2 net atmospheric flux (NAF) in a stratified reservoir. A total of 16 field campaigns were conducted from the summer stratification to fall turnover period in 2017. A random forest (RF) model was developed to estimate the pCO2 using concurrently measured water quality variables. The results showed that the vertical distribution of pCO2 and associated temporal variations of the NAF are closely related to the stratification strength of the reservoir. The reservoir surface pCO2 was supersaturated (1542 µatm) in summer (July 11), but this decreased to undersaturation as algae grew. Meanwhile, dissolved CO2 continuously accumulated below the reservoir mixed-layer due to the thermal stratification barrier and organic-rich floodwater intrusion. Vertical mixing began instantly as the stratification strength began to weaken in mid-October, and the surface pCO2 increased sharply up to 1934 µatm. Consequently, the NAF drastically increased to 3235 mg−CO2 m−2·day−1, which implies that the NAF changes seasonally and large CO2 pulsing occurs during the turnover events. The results provide valuable information about pCO2 variability and physical mixing processes, as well as carbon budget estimation in stratified reservoirs, and offer an improved understanding of these phenomena.

ACS Style

Hyungseok Park; Sewoong Chung. pCO2 Dynamics of Stratified Reservoir in Temperate Zone and CO2 Pulse Emissions During Turnover Events. Water 2018, 10, 1347 .

AMA Style

Hyungseok Park, Sewoong Chung. pCO2 Dynamics of Stratified Reservoir in Temperate Zone and CO2 Pulse Emissions During Turnover Events. Water. 2018; 10 (10):1347.

Chicago/Turabian Style

Hyungseok Park; Sewoong Chung. 2018. "pCO2 Dynamics of Stratified Reservoir in Temperate Zone and CO2 Pulse Emissions During Turnover Events." Water 10, no. 10: 1347.

Journal article
Published: 01 May 2018 in Science of The Total Environment
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Inland waters are substantial sources of atmospheric carbon, but relevant data are rare in Asian monsoon regions including Korea. Emissions of CO to the atmosphere depend largely on the partial pressure of CO (pCO) in water; however, measured pCO data are scarce and calculated pCO can show large uncertainty. This study had three objectives: 1) to examine the spatial variability of pCO in diverse surface water systems in Korea; 2) to compare pCO calculated using pH-total alkalinity (Alk) and pH-dissolved inorganic carbon (DIC) with pCO measured by an in situ submersible nondispersive infrared detector; and 3) to characterize the major environmental variables determining the variation of pCO based on physical, chemical, and biological data collected concomitantly. Of 30 samples, 80% were found supersaturated in CO with respect to the overlying atmosphere. Calculated pCO using pH-Alk and pH-DIC showed weak prediction capability and large variations with respect to measured pCO. Error analysis indicated that calculated pCO is highly sensitive to the accuracy of pH measurements, particularly at low pH. Stepwise multiple linear regression (MLR) and random forest (RF) techniques were implemented to develop the most parsimonious model based on 10 potential predictor variables (pH, Alk, DIC, Uw, Cond, Turb, COD, DOC, TOC, Chla) by optimizing model performance. The RF model showed better performance than the MLR model, and the most parsimonious RF model (pH, Turb, Uw, Chla) improved pCO prediction capability considerably compared with the simple calculation approach, reducing the RMSE from 527-544 to 105μatm at the study sites.

ACS Style

Sewoong Chung; Hyungseok Park; Jisu Yoo. Variability of pCO2 in surface waters and development of prediction model. Science of The Total Environment 2018, 622-623, 1109 -1117.

AMA Style

Sewoong Chung, Hyungseok Park, Jisu Yoo. Variability of pCO2 in surface waters and development of prediction model. Science of The Total Environment. 2018; 622-623 ():1109-1117.

Chicago/Turabian Style

Sewoong Chung; Hyungseok Park; Jisu Yoo. 2018. "Variability of pCO2 in surface waters and development of prediction model." Science of The Total Environment 622-623, no. : 1109-1117.

Journal article
Published: 30 November 2016 in Journal of The Korean Society of Agricultural Engineers
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Application of EFDC Model to an Agricultural Reservoir for Assessing the Effect of Point Source Bypassing Agricultural Reservoir;Eutrophication;Water Quality;EFDC;Point Source Bypass; Agricultural reservoirs in Korea have been recognized as an emerging resource for recreational and cultural activities for residents. However, most of the reservoirs are eutrophic and showing high level of contamination with nuisance algal bloom and offensive odor during the summer. For better management and restoration of the reservoirs' water quality, scientific modeling approaches could be used to diagnose the problems and evaluate the efficacy of alternative control measures. The objectives of this study were to validate the performance of a three-dimensional (3D) hydrodynamic and water quality model (Environmental Fluid Dynamics Code, EFDC) for a eutrophic agricultural reservoir and assess the effect of bypassing of the effluent from a wastewater treatment plant on the reservoir water quality. The 3D model successfully simulated the temporal variations of water temperature, DO, TOC, nitrogen and phosphorus species and Chl-a observed in 2014 and also captured their spatial heterogeneity in the reservoir. The simulation results indicated that the point source bypassing may reduce the T-N and T-P concentrations of the reservoir by 6.6 ~ 8.2 %, and 1.7 ~ 16.8 %, respectively. The bypassing, however, showed a marginal effect on the control of TOC due to the increased algal biomass associated with the increased water retention time after bypassing as well as the lower TOC level of the effluent compared to the ambient reservoir water.

ACS Style

Ng Min Kim; Hyung Seok Park; Se Woong Chung. Application of EFDC Model to an Agricultural Reservoir for Assessing the Effect of Point Source Bypassing. Journal of The Korean Society of Agricultural Engineers 2016, 58, 9 -21.

AMA Style

Ng Min Kim, Hyung Seok Park, Se Woong Chung. Application of EFDC Model to an Agricultural Reservoir for Assessing the Effect of Point Source Bypassing. Journal of The Korean Society of Agricultural Engineers. 2016; 58 (6):9-21.

Chicago/Turabian Style

Ng Min Kim; Hyung Seok Park; Se Woong Chung. 2016. "Application of EFDC Model to an Agricultural Reservoir for Assessing the Effect of Point Source Bypassing." Journal of The Korean Society of Agricultural Engineers 58, no. 6: 9-21.

Journal article
Published: 30 September 2016 in Journal of Korean Society on Water Environment
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ACS Style

Se-Woong Chung; Ji-Su Yoo; Hyung-Seok Park; S. Geoffrey Schladow. Estimation of CO 2 Emission from a Eutrophic Reservoir in Temperate Region. Journal of Korean Society on Water Environment 2016, 32, 433 -441.

AMA Style

Se-Woong Chung, Ji-Su Yoo, Hyung-Seok Park, S. Geoffrey Schladow. Estimation of CO 2 Emission from a Eutrophic Reservoir in Temperate Region. Journal of Korean Society on Water Environment. 2016; 32 (5):433-441.

Chicago/Turabian Style

Se-Woong Chung; Ji-Su Yoo; Hyung-Seok Park; S. Geoffrey Schladow. 2016. "Estimation of CO 2 Emission from a Eutrophic Reservoir in Temperate Region." Journal of Korean Society on Water Environment 32, no. 5: 433-441.

Journal article
Published: 31 August 2016 in Journal of Environmental Impact Assessment
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ACS Style

Hyung Seok Park; Sung Wan Yoon; Se Woong Chung; Hyun Sik Hwang. Effect of Pollutants Control Measures in So-oak Watershed on the Control of Algae Growth in Daecheong Reservoir. Journal of Environmental Impact Assessment 2016, 25, 248 -260.

AMA Style

Hyung Seok Park, Sung Wan Yoon, Se Woong Chung, Hyun Sik Hwang. Effect of Pollutants Control Measures in So-oak Watershed on the Control of Algae Growth in Daecheong Reservoir. Journal of Environmental Impact Assessment. 2016; 25 (4):248-260.

Chicago/Turabian Style

Hyung Seok Park; Sung Wan Yoon; Se Woong Chung; Hyun Sik Hwang. 2016. "Effect of Pollutants Control Measures in So-oak Watershed on the Control of Algae Growth in Daecheong Reservoir." Journal of Environmental Impact Assessment 25, no. 4: 248-260.

Journal article
Published: 01 June 2016 in Environmental Modelling & Software
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Sensitivity and uncertainty analysis of contaminant fate and transport modeling have received considerable attention in the literature. In this study, our objective is to elucidate the uncertainty pertaining to micropollutant modeling in the sediment-water column interface. Our sensitivity analysis suggests that not only partitioning coefficients of metals but also critical stress values for cohesive sediment affect greatly the predictions of suspended sediment and metal concentrations. Bayesian Monte Carlo is used to quantify the propagation of parameter uncertainty through the model and obtain the posterior parameter probabilities. The delineation of periods related to different river flow regimes allowed optimizing the characterization of cohesive sediment parameters and effectively reducing the overall model uncertainty. We conclude by offering prescriptive guidelines about how Bayesian inference techniques can be integrated with contaminant modeling and improve the methodological foundation of uncertainty analysis.

ACS Style

Eunju Cho; George Arhonditsis; Jeehyeong Khim; Sewoong Chung; Tae-Young Heo. Modeling metal-sediment interaction processes: Parameter sensitivity assessment and uncertainty analysis. Environmental Modelling & Software 2016, 80, 159 -174.

AMA Style

Eunju Cho, George Arhonditsis, Jeehyeong Khim, Sewoong Chung, Tae-Young Heo. Modeling metal-sediment interaction processes: Parameter sensitivity assessment and uncertainty analysis. Environmental Modelling & Software. 2016; 80 ():159-174.

Chicago/Turabian Style

Eunju Cho; George Arhonditsis; Jeehyeong Khim; Sewoong Chung; Tae-Young Heo. 2016. "Modeling metal-sediment interaction processes: Parameter sensitivity assessment and uncertainty analysis." Environmental Modelling & Software 80, no. : 159-174.

Journal article
Published: 28 February 2015 in Journal of Environmental Impact Assessment
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ACS Style

Hyung Seok Park; Hwan Gyu Choi; Se Woong Chung. Analysing the effect of impervious cover management techniques on the reduction of runoff and pollutant loads. Journal of Environmental Impact Assessment 2015, 24, 16 -34.

AMA Style

Hyung Seok Park, Hwan Gyu Choi, Se Woong Chung. Analysing the effect of impervious cover management techniques on the reduction of runoff and pollutant loads. Journal of Environmental Impact Assessment. 2015; 24 (1):16-34.

Chicago/Turabian Style

Hyung Seok Park; Hwan Gyu Choi; Se Woong Chung. 2015. "Analysing the effect of impervious cover management techniques on the reduction of runoff and pollutant loads." Journal of Environmental Impact Assessment 24, no. 1: 16-34.

Journal article
Published: 30 September 2014 in Journal of Korean Society on Water Environment
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ACS Style

Sung Wan Yoon; Gwan Yeong Park; Se Woong Chung; Boo Sik Kang. Projection of the Climate Change Effects on the Vertical Thermal Structure of Juam Reservoir. Journal of Korean Society on Water Environment 2014, 30, 491 -502.

AMA Style

Sung Wan Yoon, Gwan Yeong Park, Se Woong Chung, Boo Sik Kang. Projection of the Climate Change Effects on the Vertical Thermal Structure of Juam Reservoir. Journal of Korean Society on Water Environment. 2014; 30 (5):491-502.

Chicago/Turabian Style

Sung Wan Yoon; Gwan Yeong Park; Se Woong Chung; Boo Sik Kang. 2014. "Projection of the Climate Change Effects on the Vertical Thermal Structure of Juam Reservoir." Journal of Korean Society on Water Environment 30, no. 5: 491-502.

Journal article
Published: 01 September 2014 in Science of The Total Environment
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There has been an increasing concern in recent years over the presence of numerous micropollutants in river water. Simultaneously, risk assessment of micropollutants has become increasingly important due to their high toxicity. Therefore, the aims of this study were to characterize the levels of micropollutants in rivers, to identify the sources of these pollutants, and to evaluate their risk quotients (RQ) to the ecological system. Monitoring data from 159 sites distributed across four major rivers in Korea were collected from the Ministry of the Environment (KME) reports. Tests were performed to check for the presence of 35 pollutants in river waters, from which 29 pollutants were detected. Organochlorine pesticides (OCPs) occurred most frequently, at low concentrations, whereas volatile organic compounds (VOCs) and phthalates were detected at higher concentrations. Based on this study, it was suggested that the factories near the sampling sites where pollutants were found represent one of the main sources of chemicals. After comparing the industrial activities with the measured pollutants, although the released amounts were not reported, representative intermediate chemicals were found in the river water. The RQs of most VOCs were below one, despite their concentration range being higher, compared with other pollutants. Methyl bromide and di-n-octyl phthalate occurred frequently in the Han River Basin and the Nakdong River Basin, respectively, and their RQs were consistently high, so further studies should focus on their exact emission source in order to reduce ecological risk. The results suggest that it will be necessary to develop methods of risk assessment that are more tailored to the various micropollutants present in river water, in addition to the implementation of water treatment systems to reduce ecological risk.

ACS Style

Eunju Cho; Jeehyeong Khim; Sewoong Chung; Dongil Seo; Younggyu Son. Occurrence of micropollutants in four major rivers in Korea. Science of The Total Environment 2014, 491-492, 138 -147.

AMA Style

Eunju Cho, Jeehyeong Khim, Sewoong Chung, Dongil Seo, Younggyu Son. Occurrence of micropollutants in four major rivers in Korea. Science of The Total Environment. 2014; 491-492 ():138-147.

Chicago/Turabian Style

Eunju Cho; Jeehyeong Khim; Sewoong Chung; Dongil Seo; Younggyu Son. 2014. "Occurrence of micropollutants in four major rivers in Korea." Science of The Total Environment 491-492, no. : 138-147.

Journal article
Published: 28 July 2014 in Ecological Modelling
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A three-dimensional coupled hydrodynamic and ecological model, ELCOM–CAEDYM, was extended to include buoyancy control dynamics for cyanobacteria, and validated in the stratified Daecheong Reservoir (Korea). Specifically, the model was used to explore the physical and biological processes that determined the temporal and spatial variability of Microcystis aeruginosa (hereafter Microcystis) biomass during an abnormally intense mono-specific bloom event. Inclusion of the buoyancy control function within the coupled model considerably improved the model predictability by capturing the biomass accumulation at the surface during the bloom, and the shift of the dominant group from green algae to cyanobacteria. Results indicated that physical processes, particularly inflow mixing, played a dominant role in determining the spatial heterogeneity of Microcystis biomass through the local control of nutrient availability. In addition, the shallow mixed layer depth (zm) relative to the euphotic depth (zp) under a stable thermal stratification provided a perfect physical habitat for the dominance of this cyanobacteria relative to other species, due to their buoyancy control capability. This work demonstrates that the coupled hydrodynamic and ecological modeling has advanced to a stage where it may be used to interpret field data and subject to a suitable level of validation, the model may be used as a management decision support tool.

ACS Style

S.W. Chung; J. Imberger; M.R. Hipsey; H.S. Lee. The influence of physical and physiological processes on the spatial heterogeneity of a Microcystis bloom in a stratified reservoir. Ecological Modelling 2014, 289, 133 -149.

AMA Style

S.W. Chung, J. Imberger, M.R. Hipsey, H.S. Lee. The influence of physical and physiological processes on the spatial heterogeneity of a Microcystis bloom in a stratified reservoir. Ecological Modelling. 2014; 289 ():133-149.

Chicago/Turabian Style

S.W. Chung; J. Imberger; M.R. Hipsey; H.S. Lee. 2014. "The influence of physical and physiological processes on the spatial heterogeneity of a Microcystis bloom in a stratified reservoir." Ecological Modelling 289, no. : 133-149.

Journal article
Published: 30 August 2013 in Journal of Environmental Impact Assessment
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ACS Style

Yoon Cheol Cha; Se Woong Chung; Sung Wan Yoon. Forecasting the Effect of Global Warming on the Water Temperature and Thermal Stratification in Daecheong Reservoir. Journal of Environmental Impact Assessment 2013, 22, 329 -343.

AMA Style

Yoon Cheol Cha, Se Woong Chung, Sung Wan Yoon. Forecasting the Effect of Global Warming on the Water Temperature and Thermal Stratification in Daecheong Reservoir. Journal of Environmental Impact Assessment. 2013; 22 (4):329-343.

Chicago/Turabian Style

Yoon Cheol Cha; Se Woong Chung; Sung Wan Yoon. 2013. "Forecasting the Effect of Global Warming on the Water Temperature and Thermal Stratification in Daecheong Reservoir." Journal of Environmental Impact Assessment 22, no. 4: 329-343.

Journal article
Published: 30 June 2013 in Journal of Hydro-environment Research
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The fate and transport of contaminants induced into a deep and stratified reservoir after flood events are largely governed by the thermal structure of the reservoir. For last two decades, diverse three-dimensional (3D) hydrodynamic and water quality models have been developed and applied for supporting reservoir water quality management, but validation of the models to simulate stratification processes in deep and dendritic reservoirs in monsoon climate region is rare. The study was aimed to evaluate the performance of a 3D hydrodynamic model, ELCOM, in a deep and dendritic reservoir located in Geum River of Korea for simulating heat fluxes and stratification processes. The model was applied to two different hydrological years; dry (2008) and normal (2009), and validated against extensive field data. The model showed satisfactory performance in simulating the water temperature profiles within the acceptable errors at all monitoring stations. The turbid density flows induced by flood events incurred a significant modification of the structure of thermal stratification, and which was well replicated by the model. In addition, the model reasonably captured the instant surface vertical mixings that observed during flood and strong wind events. The net heat flux across the free surface was positive (gain heat) from April to September, which resulted in the development of thermal stratification in the reservoir.

ACS Style

Heungsoo Lee; Sewoong Chung; Ingu Ryu; Jungkyu Choi. Three-dimensional modeling of thermal stratification of a deep and dendritic reservoir using ELCOM model. Journal of Hydro-environment Research 2013, 7, 124 -133.

AMA Style

Heungsoo Lee, Sewoong Chung, Ingu Ryu, Jungkyu Choi. Three-dimensional modeling of thermal stratification of a deep and dendritic reservoir using ELCOM model. Journal of Hydro-environment Research. 2013; 7 (2):124-133.

Chicago/Turabian Style

Heungsoo Lee; Sewoong Chung; Ingu Ryu; Jungkyu Choi. 2013. "Three-dimensional modeling of thermal stratification of a deep and dendritic reservoir using ELCOM model." Journal of Hydro-environment Research 7, no. 2: 124-133.

Journal article
Published: 31 December 2011 in Journal of Korea Water Resources Association
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ACS Style

Se-Woong Chung; Jung-Hyun Lee; Heung-Soo Lee; Seung-Jin Maeng. Uncertainty of Discharge-SS Relationship Used for Turbid Flow Modeling. Journal of Korea Water Resources Association 2011, 44, 991 -1000.

AMA Style

Se-Woong Chung, Jung-Hyun Lee, Heung-Soo Lee, Seung-Jin Maeng. Uncertainty of Discharge-SS Relationship Used for Turbid Flow Modeling. Journal of Korea Water Resources Association. 2011; 44 (12):991-1000.

Chicago/Turabian Style

Se-Woong Chung; Jung-Hyun Lee; Heung-Soo Lee; Seung-Jin Maeng. 2011. "Uncertainty of Discharge-SS Relationship Used for Turbid Flow Modeling." Journal of Korea Water Resources Association 44, no. 12: 991-1000.

Journal article
Published: 01 May 2011 in Water Science and Technology
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Persistent turbidity in reservoirs and their downstream after flood events is one of most important environmental issues in Korea. Recently, modification of withdrawal facility and installation of a new selective withdrawal structure (SWS) have been implemented for the mitigation of downstream impact and sediment loading into water treatment facilities. This study was to explore the characteristics of flood density flow induced into Soyang Reservoir and the transport processes of suspended sediments (SS) through application of coupled two-dimensional hydrodynamic and particle dynamic models (TM-1, TM-2 and TM-3). The TM-3 including a turbidity attenuation rate as a lumped parameter showed best performance in reproducing the magnitude and distribution of SS in the reservoir. The validated model was applied to evaluate the effectiveness of SWS, which was designed for the reservoir, with 6 different historical flood events. The magnitude of vertical mixing of the turbidity plume and its persistence within the reservoir were closely correlated to the ratio of the volume of turbidity flow to the total reservoir storage (the θ value). The operation of SWS showed a positive effect as long as θ is between 0.3 and 0.6 but negative when θ = 0.83 for the study reservoir, thus it should be optimized based on the θ value for a better management of the reservoir.

ACS Style

I. G. Ryu; S. W. Chung; S. W. Yoon. Modelling a turbidity current in Soyang reservoir (Korea) and its control using a selective withdrawal facility. Water Science and Technology 2011, 63, 1864 -1872.

AMA Style

I. G. Ryu, S. W. Chung, S. W. Yoon. Modelling a turbidity current in Soyang reservoir (Korea) and its control using a selective withdrawal facility. Water Science and Technology. 2011; 63 (9):1864-1872.

Chicago/Turabian Style

I. G. Ryu; S. W. Chung; S. W. Yoon. 2011. "Modelling a turbidity current in Soyang reservoir (Korea) and its control using a selective withdrawal facility." Water Science and Technology 63, no. 9: 1864-1872.

Journal article
Published: 01 June 2010 in Journal of Environmental Sciences
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The aim of this study was to determine the unit load of NPS (non-point source) pollutants including organic variables such as BOD (biochemical oxygen demand), COD (chemical oxygen demand) and DOC (dissolved organic carbon), nitrogen and phosphorus constituents, and suspended solids (SS) and their event mean concentration (EMC) of runoff flows from a water-shed of mixed forest land use by intensive field experiments. Field monitoring for continuous measurements of rainfall, flow, and water quality was conducted over 12 storm events during 2008–2009 using automated and manual sampling methods. The EMCs of individual runoff event were estimated for each water quality constituent based on the flow rate and concentration data of runoff discharge. The average EMCs of BOD, COD, DOC, SS, TN (total nitrogen), NH4+-N, NO3−-N, TP (total phosphorus), PO43−-P from the mixed forest land were 1.794, 3.498, 1.462, 10.269, 0.862, 0.044, 0.634, 0.034, and 0.005 mg/L, respectively. The annual unit loads of BOD, COD, DOC, SS, TN, NH4+-N, NO3−-N, TP and PO43−-P were estimated as 66.9, 133.2, 55.5, 429.8, 36.5, 1.6, 26.9, 1.3 and 0.1 kg/(ha·yr), respectively. In addition, affecting parameters on the EMCs were investigated by statistic analysis of the field data. As a result, significant correlations with precipitation, rainfall intensity, and total runoff flows were found in most constituents.

ACS Style

Sung Wan Yoon; Se Woong Chung; Dong Geun Oh; Jae Woon Lee. Monitoring of non-point source pollutants load from a mixed forest land use. Journal of Environmental Sciences 2010, 22, 801 -805.

AMA Style

Sung Wan Yoon, Se Woong Chung, Dong Geun Oh, Jae Woon Lee. Monitoring of non-point source pollutants load from a mixed forest land use. Journal of Environmental Sciences. 2010; 22 (6):801-805.

Chicago/Turabian Style

Sung Wan Yoon; Se Woong Chung; Dong Geun Oh; Jae Woon Lee. 2010. "Monitoring of non-point source pollutants load from a mixed forest land use." Journal of Environmental Sciences 22, no. 6: 801-805.