• Journal of Environmental Health Sciences
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• v.28 no.2
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• pp.61-69
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• 2002

Oship stream is located nearby south eastern coasts. This study was performed to find out waters quality modeling and then to predict water quality of Oship stream. Based on survey data, BOD, T-N, T-P calibration and verification result were in good agreement with measured value within mean coefficient variance(MSE) value, which were 13.9%, 9.0%, 26.5% and 19.5%, 12.0%, 16.5%, respectively. Sectional water quality predictions of the main stream of Oship stream are executed on the basis of the following cases 1) with sewage treatment of Dogye-eup 2) reduction of mine wastewater treatment of 80% in th basin. As a result, BOD, T-P improvement rates at down stream of Oship stream, case 1) were appeared 12.2%, 22.2%, case 2) maximum sulfate ion and conductivity reduction removal rate of Oship stream were 58%, 68%. The main pollution sources of Oship-stream were almost domestic wastewater and mine wastewater discharged from Dogye-eup which located in uppers stream. The large effects will appear after the construction of Dogye sewage water treatment plant which remove the organic matter and nutrients in these sewage water. The waste water from mine can not easily to treat for characteristics of effluence and economic problems. However, to achieve the goal of water quality in Oship-stream water system, treatments of those are necessary.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2001.10a
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• pp.412-416
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• 2001

Among water quality models, WASP5 was applied to Boryeong freshwater lake, as a part of Water Quality Management System. The WASP modeling system is a generalized modeling framework for contaminant fate and transport in surface waters. The simulated result was compaired with actual measurement. So, before and after making freshwater lake were compaired. After this research, the lake may have eutrophication and water quality would be worse after making the lake as freshwater lake. Therefore, to make the freshwater lake better, more appropriate plan is necessary.

• Journal of Korean Society on Water Environment
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• v.24 no.5
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• pp.581-591
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• 2008

Most of our rivers are fragmented by the presence of at least one large dam. Dams are often the most substantial controller of the flow regimes and aquatic environments of natural river system. The quality of downstream water released from a stratified reservoir is highly dependent on upstream reservoir water quality. Thus, an integrated modeling approach is more efficient, compared to fragmented modeling approach, and necessary to better interpret the impact of dam operation on the down stream water quality. The objectives of this study were to develop an integrated reservoir-river modeling system for Daecheong Reservoir and its downstream using a two-dimensional laterally averaged hydrodynamic and water quality model, and evaluate the model's performance against field measurement data. The integrated model was calibrated and verified using filed data obtained in 2004 and 2006. The model showed satisfactory performance in predicting temporal variations of water stage, temperature, and suspended solid concentration. In addition, the reservoir-river model showed efficient computation time as it took only 3 hours for one year simulation using personal computer (1.88 Ghz, 1.00 GB RAM). The suggested modeling system can be effectively used for assisting integrated management of reservoir and river water quality.

• Spatial Information Research
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• v.18 no.4
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• pp.13-22
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• 2010

For implementing TMDL(Total Maximum Daily Loading) to adopt more effective management of water pollution, water quality modeling is pre-requisite and such modeling requires the extraction of stream centerline. The institutes responsible for the water quality modeling, however, generates the stream centerline with their own criteria and this lead to low accuracy of the extracted centerline as well as different modeling results for the same watershed. Therefore, this study mainly focused on the development of extraction method of the stream centerline. For that, an automated method has been developed through the integration of the centerline extraction method using a maximum inscribed circle with GIS. The result has shown that the newly developed method could enable to represent more details of the stream topography along with enhanced accuracy compared with conventional extraction method. Furthermore, the new method can afford centerline extraction for the island areas which has been the limitation of the conventional method thereby supporting water quality modeling in a detailed level.

• Journal of Korean Society on Water Environment
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• v.30 no.4
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• pp.429-440
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• 2014

This study was conducted to investigate the main cause of water quality deterioration during the spring season in the transition zone between the South Han River and the river-reservoir Paldang. A water quality model modified from QUAL2E (U.S.EPA) was used, and the model showed that eutrophication and algal production in the low flow season affected about 60% of the organic pollution at the downstream of the South Han River. This result means that phosphorus control is prior to external organic material management to ameliorate the deterioration of water quality in the water body.

• Journal of Korea Water Resources Association
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• v.44 no.6
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• pp.439-447
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• 2011

This study aims to test the feasibility of combined use of EFDC (Environmental Fluid Dynamics Code) hydrodynamic model and WASP7.3 (Water Quality Analysis Program) model to improve accuracy of water quality predictions of the Yongdam Lake, Korea. The orthogonal curvilinear grid system was used for EFDC model to represent riverine shape of the study area. Relationship between volume, surface and elevation results were checked to verify if the grid system represents morphology of the lake properly. Monthly average boundary water quality conditions were estimated using the monthly monitored water quality data from Korean Ministry of Environment DB system. Monthly tributary flow rates were back-routed using dam discharge data and allocated in proportion to each basin area as direct measurements were not available. The optimum number of grid system was determined to be 372 horizontal cells and 10 vertical layers of the site for 1 year simulation of hydrodynamics and water quality out of iterative trials. Monthly observed BOD, TN, TP and Chl-a concentrations inside the lake were used for calibration of WASP7.3 model. This study shows that EFDC and WASP can be used in series successfully to improve accuracy in water quality modeling. However, it was observed that the amount of data to develop inflow water quality and flow rate boundary conditions and water quality data inside lake for calibration were not enough for accurate modeling. It is suggested that object-oriented data collection systems would be necessary to ensure accuracy of EFDC-WASP model application and thus for efficient lake water quality management strategy development.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.1
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• pp.121-129
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• 2008

Major factors affecting water quality in rivers are transportation, input of pollutant loads and kinetic transformation of pollutants. Government level decision makings on water quality management are based on steady state water quality modeling. However, it is more than often that such a steady state assumption is far from real situations in rivers. Therefore, it is unavoidable to have modeling errors in water quality modeling especially for steady state modeling for longer period of time. Authors attempted to identify sources of errors in results of steady state models and thus tried to find out ways to minimize those errors. Three water quality models, QUAL2E (Brown et al., 1983), QUAL2K (Chapra et al., 2006) and CAP (Seo and Lee, 2000) were applied to the lower stream of the Geum River. $BOD_5$ and COD tend to underestimate observed data while TN and TP showed relatively smaller errors. QUAL2E model provided best calibration results for BOD5 and TP and QUAL2K model showed best calibration results for TN. Since these errors are only relative values, it was difficult to conclude which model is better performing in certain situations. The most probable reasons for errors in water quality modeling are; 1) inappropriate consideration on flow characteristics, 2) lack of information on incoming pollutant load and 3) inappropriate location of sampling for water quality analysis.

• Journal of Korean Society on Water Environment
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• v.28 no.6
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• pp.866-881
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• 2012

Han River is a complex water system consisting of many lakes. The water quality of Lake Paldang is significantly affected by incoming flows, which are the South and North branches of the Han River, and the Kyungan Stream. In order to manage the water quality of the Lake Paldang, we should consider the entire water body where the incoming flows are included. The objectives of this study are to develop an integrated river and lake modeling system for Han River system using a multidimensional dynamic model and evaluate the model's performance against field measurement data. The integrated model was calibrated and verified using field measurement data obtained in 2007 and 2008. The model showed satisfactory performance in predicting temporal variations of water level, flow rate and temperature. The Root Mean Square Error (RMSE) for water temperature simulation were $0.88{\sim}2.13^{\circ}C$ (calibration period) and $1.05{\sim}2.00^{\circ}C$ (verification period) respectively. And Nash-Sutcliffe Efficiency (NSE) for water temperature simulation were 1089~0.98 (calibration period) and 0.90~0.98 (verification period). Utilizing the validated model, we analyzed the spatial and temporal distributions of temperature within Han River system. The variations of temperature along the river reaches and vertical thermal profiles for each lakes were effectively simulated with developed model. The suggested modeling system can be effectively used for integrated water quality management of water system consisting of many rivers and lakes.

• Journal of Korean Society of Water and Wastewater
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• v.16 no.6
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• pp.700-709
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• 2002

Present condition of the Youngsan River pollution is serious. Concentrations of organic materials and nutrients are high and algal bloom takes place frequently. The pollution is mainly caused by domestic wastewater input from urban areas like Kwangju and Naju City. In this study, 6 times of water quality surveys were done for mainstream and tributaries. Delivery ratios of each tributaries are calculated with the water quality and flow data. With Arc/View GIS, sub-basin are divided and pollution loads are estimated. These data are used for water quality modeling. River quality improvement effects are analysed with 5 scenarios including process upgrade of present WWTPs and construction of new WWTPs. These scenarios are applied for the Youngsan River based on the 7Q10 and Q275. And total wastewater treatment cost in the basin is analysed for each scenario.

• Proceedings of the Korea Water Resources Association Conference
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• 2004.05b
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• pp.1400-1403
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• 2004

The current industrial development and the Increase of population along Nakdong River have produced a rapid Increase of wastewater discharge. This has resulted in problem of water quality control and management. Although many efforts have been carried out, water quality has not significantly improved. The goal of this study is to design a NGIS-based water quality management system for the scientific water quality control and management in the Nakdong River. For general water quality analysis, QULA2E model was applied to the Nakdong River. A sensitivity analysis was made to determine significant parameters and an optimization was made to estimate optimal values. The calibration and verification were performed by using observed water quality data for Nakdong River. A water qualify management system for Nakdong River was made by connecting the QUAL2E model to ArcView. It allows a Windows-based Graphic User Interface(GUI) to implement all operation with regard to water quality analysis. The modeling system in this study will be an efficient NGIS for planning of water quality management.