• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3B
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• pp.291-300
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• 2006

In this study a statistical water quality monitoring network design of Kyung-An stream is proposed. Water quality data for the design is obtained by QUAL2E model simulation. The observed monthly average water quality data from March to November in Kyung-An stream has been applied to this study. HEC-RAS model is also used for QUAL2E hydrauric parameter estimation. Before QUAL2E water quality parameter estimation, FORA is performed to reduce the number of parameters to be estimated, and then water quality parameters are calibrated with a observed monthly average data. Using these simulated water quality data, the number of gage station and its location are estimated by kriging theory and branch & boundary method. Such a network design is based on two case; average flow and low flow case, respectively. Next, proportional sampling method is applied to estimate the sampling frequency.

• Journal of Korea Water Resources Association
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• v.38 no.6 s.155
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• pp.505-515
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• 2005

Two representative river water quality models have been compared in this paper. The steady water quality model, QUAL2E, and the unsteady model, CE-QUAL-RIV1, have been chosen for comparative simulations. Under same reaction coefficients and boundary conditions, the water quality of the Geum river below the Daechung dam has been simulated using two different models, and the water quality equations are compared each other. Since basic model algorithm is very close, the input data required for model run is very similar. Upon the simulation under steady condition, the results of two models show very good agreement especially for BOD, DO, and $NH_3-N$, while the results of specific constituent such as dissolved P is quite different. As a result, dominant water quality parameters to compute each corresponding water quality variables are summarized and tablized through the sensitivity analysis.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.1343-1347
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• 2005

본 연구에서는 영산강 유역을 대상유역으로 영산강을 양질의 수자원으로 보전함으로서 수생태계 회복 및 영산호 수자원의 다목적 이용을 도모하기 위한 기초자료를 제시하였다. 이를 위해 영산강 유역을 11개 소유역으로 구분하고, 각 소유역별로 조사$\cdot$분석된 자료를 QUAL2E모형에 입력하여 장래수질예측을 실시하였다. 수질예측 결과를 토대로 각 하도구간에 설정된 목표수질을 만족하도록 오염부하량을 삭감하여 소유역별 최대허용오염부하량(Total Maximum Daily Load)을 제시하였다.

• Journal of Korean Society on Water Environment
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• v.20 no.3
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• pp.223-230
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• 2004

The QUAL2E and Box-Jenkins time series model were applied to the Miho river, a main tributary of the Geum river, to predict water quality. The models are widely used to predict water quality in rivers and watersheds because of its accuracy. As results of the study, we concluded as follows: Pollutant loadings in upper stream of Miho river were determined to 57,811 kgBOD/d, 19,350 kgTN/d, and 5,013 kgTP/d. The loading of TN in Mushim river was 19,450 kgTN/d, respectively. As the mass loadings were compared with pollutant sources, it concluded that the farming livestock contributed highly to mass emissions of BOD and TP and the population contributed to TN mass loading. The observed water quality values were applied to the models to verify and the models were used to predict the water quality. The QUAL2E Model predicted the concentrations of DO, BOD, TN and TP with high accuracy, but not for E-Coli. The Box-Jenkins time series model also showed high prediction for DO, BOD and TN. However, the concentrations of TP and E-Coli were poorly predicted. The result shows that the QUAL2E model is more applicable in Miho basin for prediction of water quality compared to Box-Jenkins time series model.

• Journal of Environmental Impact Assessment
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• v.18 no.2
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• pp.99-109
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• 2009

In general, manual calibration is commonly used for the stream water quality modelling. Because the manual calibration depends upon the subjectivity and experience of the researcher, it has a problem with the objectivity of the modelling. Thus, the interest about the automatic calibration by the optimization technique is deeply increased. In this study, Influence coefficient algorithm and Genetic algorithm are introduced to develop an automatic calibration model for the QUAL2K that are the latest version of the QUAL2E. Genetic algorithm, used in this study, is very simple and easy to understand but also applicable to any complicated mathematical problem, and it can find out the global optimum solution effectively. The developed automatic calibration model is applied to the Gangneung Namdaecheon. The calibration results about the 11 water quality variables show the good correspondence between the calculated and observed water quality values.

• Journal of environmental and Sanitary engineering
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• v.15 no.3
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• pp.101-119
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• 2000

In order to establish water quality management planning in some watershed, water quality of the future of the watershed should be predicted first. The Yongsan river various pollutant sources ; sewage, industry, livestock, farming and so on. And pollutants from these sources are likely to increase even though a number of publicly owned treatment works(POTWs) are founded. Therefore, it is estimated that water quality if the river would be even worse than now in near future. In this study, water quality of the future(2001, 2006) on the Yongsan river was simulated with QUAL2E model. Concentration of three water quality parameters(BOD, T-N, T-P) was predicted according to dry season, low flow season, average flow season of the river with and without POTWs. The results of this study showed the significant contrast in concentration between with and without POTWs, specially in terms of T-N and T-P. Therefore, POTWs must be founded around the Yongsan river and more advanced treatment should be considered. And because these parameters are mostly affected by polluants from upper watershed, including Kwangiudcheon, water quality management planning on the Yongsan river might be focused on this area.

• Korean Journal of Environmental Agriculture
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• v.14 no.1
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• pp.7-14
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• 1995

This research was conducted to apply the QUAL2E model to be adopted to the Nam river under current water quality conditions. The survey area of total 60 Km was divided into five reaches. Each reach was then subdivided into the uniform computational elements of 1.5 Km. Based on the stream characteristics, nine sampling stations consisting of six at main streams and three at tributaries were selected. The field data were obtained from the selected stations twice during October of 1991 and May of 1992, which represented the cold weather and low flow, also the warm weather and low flow conditions, respectively. As the results of sensitivity analysis of the model, the important parameters were the rates of BOD decay, Org-N oxidation, $NH_3-N$ oxidation, Org-P decay. The calibrated and verified results by QUAL2E model were correlation coefficient of $0.45{\sim}0.94$. The results displayed a good agreement between the variables of the field measurements and the model simulations, indicating a potential use of the QUAL2E model for the water quality assessment in the Nam River.

• Journal of Korea Water Resources Association
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• v.37 no.9
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• pp.719-727
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• 2004

Water quality models can be applied to manage the regional water quality problems and to estimate the target and allowable pollution load in watershed effectively. The optimization of state variables in the given water quality model Is necessary to build up more effective model. The least-squares method is applied to fit field observations in QUAL2E developed by U.S. EPA, which is most widely used one in the world to simulate the stream water quality, and the optimization model with constraints is constructed to estimate the parameters. The objective function of the optimization model is solved by Solver in Microsoft Excel and Monte Carlo simulation is conducted to know the influence of parameter in conventional pollutants. It is found that this technique is easily implemented and rapidly convergent computational procedure to calibrate the parameters after appling this approach in Anyang stream located in Kyonggi province mainly.

• Journal of Environmental Science International
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• v.10 no.1
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• pp.21-25
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• 2001

The Keum river has been utilized for drinking water supply of several city including Kunsan city and is deepening pollution state due to numerous municipal and industrial discharges. The concentration BOD in river is affected by the organic loading from a tributary and the algae biomass that largely happen to under eutrophication state. In the eutrophic water mass such as the Keum river, the autochthonous BOD was very important part for making a decision of water quality management, because it was accounted for majority of the total BOD. The predict of water quality has important meaning for management of water quality pollution of the Keum river. The purpose of this study will manage and predict water quality of the Keum river using QUAL-2E model considering the autochthonous BOD. The estimation of autochthonous BOD represented that the relationship between BOD and chlorophyll a. The regression equation was shown to be autochthonous BOD=$\beta$(sub)5$\times$chlorophyll a. The results of this study may be summarized as followed; The QUAL-2E model was calibrated with the data surveyed in the field of the study area in June, 1998. The calculated value by QUAL-2E model are in good agree to measured value within relative error of 7.80~20.33%. Especially, in the case of the considering autochthonous BOD, the calculated value of BOD were fairly good coincided with the observed values within relative error of 15%. But the case of not considering autochthonous BOD, relative error of BOD was shown to be 43.2%. In order to attain II grade of water quality standard in Puyo station which has a intake facility of water supply, we reduced to the pollutants loading of tributaries. In the case of removed 100% BOD of tributaries, the BOD of Puyo station was 4.07mg/$\ell$, belong to III grade of water quality standard. But in the case of removed 88% nutrient of tributaries, it was satisfied to II grade of water quality standard as below 3mg/$\ell$ of BOD. For estimation of autochthonous BOD in Keum river, we are performed simulating in accordance with reduction of nutrient load(50~100%) under conditions removal 90% organic load. Occupancy of autochthonous BOD according to nutrient loading reductions were varied from 25.97~79.51%. Occupancy of autochthonous BOD was shown to be a tendency to increasing in accordance with reduction of nutrient loading. Showing the above results, the nutrient that one of the growing factor of algae was important role in decision of BOD in the Keum river. For the water quality management of the Keum river, therefore, it is necessary to considering autochthonous BOD and to construction of advanced sewage treatment plant for nutrient removal.

• Journal of Wetlands Research
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• v.16 no.1
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• pp.1-10
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• 2014

The research grasps water quality contamination source by investigating the data that are superordinate laws and the related plans implemented for establishing water quality improvement measures of upper stream for Chung-Ju Dam, present conditions of the hydraulic and hydrology, the present conditions and plans of environment basic facilities, and present conditions of main contamination source's occurrence load and discharge load, etc. The research used the QUAL2E simulation which is being widely applied to simulation of river water quality because the QUAL2E has high credibility among water quality simulations known throughout the country. On basis of this research, regulations and politic alternatives are required in order to water quality improvement upper stream for the Chung-ju dam, especially establishing processing facilities in the region where loading amount is concentrated should be considered with the additional research regarding cost-efficient facility of pollution source.