• Journal of Korean Society of Environmental Engineers
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• v.30 no.1
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• pp.69-78
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• 2008

An integration study of watershed model(HSPF, Hydological Simulation program-Fortran) and reservoir water quality model (CE-QUAL-W2) was performed for the evaluation of turbid water management in Yongdam reservoir. The watershed model was calibrated and analyzed for flow and suspended solid concentration variation during rainy period, their results were inputted for reservoir water quality model as time-variable water temperature and turbidity. Results of the watershed model showed a good agreement with the field measurements of flow and suspended solid. Also, results of the reservoir water quality model showed a good agreement with the filed measurements of water balance, water temperature and turbidity using linkage of the watershed model results. Integration of watershed and reservoir model is an important in turbid water management because flow and turbidity in stream and high turbidity layer in reservoir could be predicted and analyzed. In this study, the integration of HSPF and CE-QUAL-W2 was applied for the turbid water management in Yongdam reservoir, where it is evaluated to be appliable and important.

• Journal of Environmental Impact Assessment
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• v.17 no.6
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• pp.349-356
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• 2008

This paper aims to understand the effects of a turbidity flow intrusion on eutrophication in Daecheong Dam Reservoir. CE-QUAL-W2, a two-dimensional hydrodynamic and water quality model, is applied. The elevation of the reservoir water surface is used to validate the hydrodynamic model parameters and maximum fluctuations in the water surface elevations reaches about 1 m in the reservoir. During the heavy storm season, July, the thermocline submerged to less than 30 m below the surface. The thickness of the thermocline also reduced to 10 to 15 m. While the average TSS in June, the beginning of the monsoon was still low but it peaked in July due to heavy rainfall. Vertical profiles of the TSS regime in July indicated higher concentration in upper water layers and then the regime moves gradually downward in accordance with the time lapse. Due to the dam spillway opening, high concentrations of TSS attributed to storm turbidity ascended to the upper water layer by following the upward current movement and then, the regime precipitated to a layer below 30 to 40 m after September.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.290-290
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• 2019

최근 우리나라 수자원 오염의 심각성에 관한 인식이 커지고 있으며, 수질 및 조류 관리의 필요성이 다양한 분야에서 증가하고 있다. 우리나라의 경우 초여름부터 장마 이전과 장마 이후부터 10월까지 호소의 영양 단계가 조류의 성장에 충분한 상태이기 때문에 남조류가 대량으로 증식된다. 하지만 기상 조건에 따라 조류의 발생 시기와 발생 정도는 매년 다르게 나타날 수 있다. 한편, 조류를 포함한 수질 모의 모형은 현재의 상태에 대한 정확한 모사를 통해 수질 관리와 미래의 예측 등 다양한 방면으로 활용된다. 따라서 복잡한 현상을 모형을 통해 재현하는 것은 중요하다. 본 연구에서는 대청호 지역을 대상으로 CE-QUAL-W2 모형을 이용하여 2016년 1월부터 2018년 7월까지 수질 및 조류의 거동을 모의하였다. 금강의 지류 하천인 소옥천에 위치한 옥천천 측정소부터 대청호 내부의 대청댐5 구간을 상류 및 하류 경계로 설정하였고, 수질 및 조류의 모의를 위해 물환경 정보시스템과 실시간 수질 정보시스템의 관측자료 및 대청댐의 운영 자료, 기상청의 기상관측 자료를 수집하였다. 모형의 안정화(warm up) 기간을 고려하여 2015년 1월부터 2018년 7월까지 주요 수질 항목인 수온, 용존산소, 총 인, 총 질소, 클로로필-a에 대한 분석을 수행하였고, 연구대상 지역 내의 대청댐6 지점의 관측값과 모의 결과를 비교 분석하였다. 수온과 용존산소, 클로로필-a의 경우 모의 결과가 관측 값을 비교적 잘 모사하였지만, 총 인과 총 질소의 경우 자동 수질 측정지점의 값과 일반수질 측정 지점의 측정 방법의 차이로 인해 오차가 다소 발생하는 것을 확인할 수 있었다. 본 연구는 CE-QUAL-W2 모형을 이용한 수질 및 조류 모의에 관한 연구로서, CE-QUAL-W2 모형을 이용한 수질 및 조류 관리에 활용될 수 있을 것으로 판단된다.

• Journal of Korean Society on Water Environment
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• v.36 no.6
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• pp.508-520
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• 2020

Dam reservoirs have been reported to contribute significantly to global carbon emissions, but unlike natural lakes, there is considerable uncertainty in calculating carbon emissions due to the complex of emission pathways. In particular, the method of calculating carbon dioxide (CO2) net atmospheric flux (NAF) based on a simple gas exchange theory from sporadic data has limitations in explaining the spatiotemporal variations in the CO2 flux in stratified reservoirs. This study was aimed to analyze the spatial and temporal CO2 distribution and mass balance in Daecheong Reservoir, located in the mid-latitude monsoon climate zone, by applying a two-dimensional hydrodynamic and water quality model (CE-QUAL-W2). Simulation results showed that the Daecheong Reservoir is a heterotrophic system in which CO2 is supersaturated as a whole and releases CO2 to the atmosphere. Spatially, CO2 emissions were greater in the lacustrine zone than in the riverine and transition zones. In terms of time, CO2 emissions changed dynamically according to the temporal stratification structure of the reservoir and temporal variations of algae biomass. CO2 emissions were greater at night than during the day and were seasonally greatest in winter. The CO2 NAF calculated by the CE-QUAL-W2 model and the gas exchange theory showed a similar range, but there was a difference in the point of occurrence of the peak value. The findings provide useful information to improve the quantification of CO2 emissions from reservoirs. In order to reduce the uncertainty in the estimation of reservoir carbon emissions, more precise monitoring in time and space is required.

• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.6
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• pp.65-76
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• 2012

Agricultural reservoir water quality simulation model (ARSIM-rev) was developed in this study for water quality simulation of a small and shallow agricultural reservoir with limited observed water quality data. Developed ARSIM-rev is a zero-dimensional water quality model because of little spatial differences in water quality between stations in a small and shallow agricultural reservoir. ARSIM-rev used same water quality reaction equations with WASP except for several equations, and daily based input parameters such as settling rate, release rate from sediment, and light extinction coefficient changed yearly based input parameters in ARSIM-rev. A number of pre- and post-processors were developed such as auto calibration and scenario analysis for ARSIM-rev. CE-QUAL-W2, WASP, and developed ARSIM-rev were applied to Mansu agricultural reservoir to evaluate model performance, and ARSIM-rev demonstrated similar model performance with CE-QUAL-W2 and WASP when low number of observed data was used for agricultural reservoir water quality simulation. Overall, developed ARSIM-rev was feasible for water quality simulation in a small and shallow agricultural reservoir with limited observed water quality data, and it can simulate agricultural reservoir water quality precisely enough like common water quality model such as CE-QUAL-W2 and WASP within a limited time.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.52-52
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• 2015

강수량이 적은 갈수기에는 하천수량이 적어 소량의 오염물질의 유입으로도 하천수질의 악화를 불러일으킬 수 있다. 특히 2014년에는 한강수계의 강수량이 예년의 46%정도이며 이로 인한 저수율은 예년의 75%정도로 저조하여 봄철 갈수기에 수질악화가 우려된다. 한강은 비교적 수질이 양호하여 녹조가 발생하는 일이 낙동강, 금강, 영산강보다 적으나 가뭄의 영향으로 하천수질 악화 및 녹조현상이 발생할 우려가 있다. 그래서 본 연구에서는 남한강과 북한강의 봄철 수질전망을 통한 녹조발생 위험도를 예측하고자 하였다. 수질예측에 사용된 모형은 미국공병단(USACE)에서 개발한 2차원 하천수리 수질모형인 CE-QUAL-W2이며, 본 연구에 이용된 CE-QUAL-W2는 K-water 통합수질예측시스템(SURIAN)을 이용하여 구축하였다. 연구 대상지역은 북한강의 소양강댐 하류와 팔당호지점, 남한강의 강천보, 여주보, 이포보 지점에 대해 조류농도에 대한 예측을 수행하였다. 미래 수질예측을 위한 유량 자료는 평년 빈도유량을 사용하였으며, 기상자료는 유사는 분석을 통해 과거기상과 가장 유사한 패턴을 보이는 년도의 기상자료를 사용하여 모형을 구동하였다. 2~4월 남한강과 북한강의 Chl-a농도에 대하여 2013~2014년 평균치와 2015년 수질예측치를 비교한 결과 북한강은 4월에 예년대비 최고 61% Chl-a 농도가 증가하는 것으로 나타났으며, 남한강은 2월에 Chl-a농도가 최고 106% 증가되는 것으로 예측되었다. 본 연구를 통해 2015년 봄철 갈수기 녹조가 예년보다 증가 할 것으로 나타났으며, 다른 수계보다 비교적 적은 농도이지만 주기적인 수질예측과 하천 모니터링을 통해 하천수질을 관리하고 수질오염을 예방하는 노력을 기울여야 할 것이다.

• Journal of Korean Society on Water Environment
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• v.23 no.2
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• pp.228-235
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• 2007

For efficient turbid water withdrawal in the Imha reservoir, a selective withdrawal facility was recently installed and operated during summer season of year 2006. In this research, CE-QUAL-W2 model was utilized to assess the efficiency of the selective withdrawal facility, in comparison with the original surface withdrawal, on turbid water management. Model calibration was carried out using data observed at four automatic monitoring stations in the reservoir. It was found that the model appropriately simulated, with the RMSE less than 5.2 NTU, the observed vertical and horizontal distributions of water temperature and turbidity as well as the location of maximum turbid water at each monitoring station. The analysis results showed that selective withdrawal is more effective in removing high turbid water than surface withdrawal as selective withdrawal contributed to reducing $35Mm^3$ of high turbidity water (> 100 NTU) in the reservoir by increasing outflows of high turbid water. Therefore, effective management of turbid water in the reservoir can be achieved by changing locations of intake depending on turbid water distribution conditions. The results of this study will provide some basic information for establishing better operation strategies to cope with turbid water problems.

• Journal of Korean Society on Water Environment
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• v.23 no.1
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• pp.52-63
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• 2007

The objectives of this study were to setup a laterally-averaged two-dimensional eutrophication model in Daecheong Reservoir, and to validate the model under two different hydrological conditions; drought year (2001) and wet year (2004). The suggested modeling approach was found to be very effective to simulate the dynamic variations of water temperature, nutrients, dissolved oxygen, and algae in the reservoir. The model satisfactorily replicated the algal bloom that happened between Janggae (Sta.4) and Haenam (Sta.5) during summer of 2001, although the peak concentration was slightly underestimated due to the laterally averaged assumption. The allochthonous phosphorus and algae induced from upstream and So-oak stream during several rainfall events were found to be most significant sources of algal bloom in 2001. In contrast to draught year, the flood events happened during summer months of 2004 tended to remove the hypolimnetic anaerobic conditions and dilute the dissolved phosphorus in the upper reach of the reservoir, and in turn mitigated algal bloom. It implies that the impact of hydrological and hydrodynamic conditions on the reservoir water quality is highly significant, and a drought year may be more vulnerable to algal bloom in the reservoir.

• Journal of Korea Water Resources Association
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• v.48 no.10
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• pp.857-868
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• 2015

Hydraulic and water quality models with high reliability are necessary for the efficient management of water quality in the reservoir. The model capacity can be demonstrated by the application for the various hydrological conditions. CE-QUAL-W2 model is laterally averaged two-dimensional hydraulic and water quality model. The W2 model, which is suitable for the narrow reservoir like the Jinyang reservoir as compared with the depth and length of waterbody, has been frequently used by many researchers. Namgang watershed is expected to increase the water demand. In this study, the W2 model is validated under two different hydrological conditions; wet year (2011) and normal year (2009). Using hydrological and water quality condition for calibration, 2011, the effect of water intake increase was simulated. The simulation results showed that the increase of water intake led to increase the concentrations in total nitrogen, total phosphorus and Chlorophyll-${\alpha}$ concentration. Especially the concentration increase was appeared during the dry season in each of up to 62.53% (Total nitrogen), 39.07% (Total phosphorus) and 232.19% (Chlorophyll-${\alpha}$). The changes of chlorophyll-${\alpha}$ is similar to those of total phosphorus concentration.

• Journal of Korea Water Resources Association
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• v.38 no.8 s.157
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• pp.655-664
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• 2005

A real-time monitoring and modeling system (RTMMS) for rainfall-induced turbidity flow, which is one of the major obstacles for sustainable use of reservoir water resources, is under development. As a prediction model for the RTMMS, a laterally integrated two-dimensional hydrodynamic and water quality model, CE-QUAL-W2 was tested by simulating the temperature stratification, density flow regimes, and temporal and spatial distributions of turbidity in a reservoir. The inflow water temperature and turbidity measured every hour during the flood season of 2004 were used as the boundary conditions. The monitoring data showed that inflow water temperature drop by 5 to $10^{\circ}C$ during rainfall events in summer, and consequently resulted in the development of density flow regimes such as plunge flow and interflow in the reservoir. The model showed relatively satisfactory performance in replicating the water temperature profiles and turbidity distributions, although considerable discrepancies were partially detected between observed and simulated results. The model was either very efficient in computation as the CPU run time to simulate the whole flood season took only 4 minutes with a Pentium 4(CPU 2.0GHz) desktop computer, which is essentially requited for real-time modeling of turbidity plume.