• Magazine of the Korean Society of Agricultural Engineers
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• v.39 no.2
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• pp.97-103
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• 1997

DO concentration in the aquatic system is important for the water quality management perspective. Water quality model uses available reaeration coefficient (K2) estimation equations in calculating DO, however, they might include inevitable uncertainty that the model output can be less reliable. In this study, the calibrated QUAL2E model for the Passaic River in New Jersey, U.S., was used to examine the effect of K2 estimation equation on the output DO concentration of the river. The model was run with six commonly used equations separately with all the other conditions remained same. The result showed that the output DO concentration profiles varied widely with different equations, and maximum difference was 4.96 mg/L for the same location which is unacceptably large. It implies that the development of reliable equation is required for proper water quality management. The unreliable model output can lead to a wrong decision in water quality management such as unnecessarily high or too low treatment of wastewater, which will cause serious effect on the community economically and socially in either case. Generating more reliable model output with slight investment to develop a site specific K$_2$ equation can improve the decision making process significantly and is highly recommended.

• Journal of Environmental Impact Assessment
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• v.18 no.1
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• pp.1-9
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• 2009

Even though the center of Cheongju city needs redevelopment because of a doughnut phenomenon, it has to be permitted within the environmental carrying capacity like a target water quality proposed on the Total maximum daily loads(TMDL) of Musim and Miho river watersheds. The aim of in this study is to identify the limit of redeveloping Cheongju downtown after analyzing its environmental carrying capacity using QUAL2E model. As a result of modeling various scenarios, the water quality of Musin river was shown that $BOD_5$ is 2.3mg/L which is the target water quality in the double of existing development plan of the Cheongju downtown. The water quality of Miho river was $BOD_5$ 3.97mg/L which is less than the target water quality of Miho B watershed in the same condition. Therefore, this means that the limit of redevelopment within the environmental carrying capacity of cheongju downtown was estimated to be the double of existing development plan.

• Journal of Korean Society on Water Environment
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• v.28 no.1
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• pp.38-49
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• 2012

In this study, we analyze statistical characteristics of influent water quality in Daejeon waste water treatment plant and apply a stochastic model for data generation. In the analysis, the influent water quality data from year 2003 to 2008, except for year 2006, are used. Among water quality variables, we find strong correlations between BOD and T-N; T-N and T-P; BOD and T-P; $COD_{Mn}$ and T-P; and BOD and $COD_{Mn}$. We also find that different water quality variables follow different theoretical probability distribution functions, which also depends on whether the seasonal cycle is removed. Finally, we generate the influent water quality data using the multi-season 1st Markov model (Thomas-Fiering model). With model parameters calibrated for the period 2003~2005, the generated data for 2007~2008 are well compared with observed data showing good agreement in general. BOD and T-N are underestimated by the stochastic model. This is mainly due to the statistical difference in observed data itself between two periods of 2003~2005 and 2007~2008. Therefore, we expect the stochastic model can be applied with more confidence in the case that the data follows stationary pattern.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.5 no.3
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• pp.221-231
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• 1993

WASP4. an estuarine or lake water quality model, wat applied to simulate future water qualities at alternative withdrawal sites for capital areas. Simulated water quality constituents were Chlorophyll a, nitrogen cycles, Phosphorus, BOD End DO. A Water budget analysis Using the monthly records of reservoir inflows and outflows between 1986 and 1990 was made to determine seasonally-averaged flowrates at model boundaries. Estimated flowrates were used. together with the seasonal water quality inputs simulated by the QUAL2E model, for the simulation of future water qualities. Sensitivities to the future pollutant inputs and possible future withdrawal alternatives were also analyzed. From simulations or future water qualities it is found that among the candidate withdrawal sites. the one located at the downstream end of the North Han River has the best future water quality in all quality constituents and the one at the downstream end of the South Han River has the worst Possible future withdrawal from the North Han River brings a slight increase or pollutant concentrations at existing withdrawal sites. but the aggravation of water quality is not significant.

• Journal of Korea Water Resources Association
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• v.45 no.7
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• pp.685-696
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• 2012

EFDC model, which is capable of handling both hydrodynamic and water quality analysis has come to use for many recent studies. In order to assess the applicability of the EFDC model, it was applied to Nakdong river. Hydrodynamic and water quality analysis were carried out for Nakbon GH and HI sections chosen as the area of study with gaged data from 2008 to 2009. The comparison was made between water quality simulation results and observed data over water temperature, COD, TOC, DO, TN and TP. On the contrary, a conversion formula was derived to calculate BOD which the EFDC model cannot directly calculates and it was compared to measured data. In this study, it was determined that the EFDC model well represents the behavior of both hydrodynamics and water quality. However, further research on COD, TOC and accurate conversion of BOD needs to be conducted for efficient application to domestic water quality analysis.

• Journal of Wetlands Research
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• v.22 no.4
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• pp.321-327
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• 2020

Recently The amount of wastewater and linked wastewater is being increased every year due to industrial development, population growth, and improvement in living standards. Linked wastewater shows the feature-low flow rate and high concentration. Therefore, it has been shown that it has a great impact on the operation of the sewage treatment plant and costs a lot for treating linked wastewater. In this study, a scenario with low increase of water quality when the total amount of the inflow of linked wastewater was entered into individual reactors is obtained. According to the result of modeling, The effluent water quality get the least increment once the water was introduced into the influent and anoxic tank. We generated the various scenarios Based on these results. scenarios are varying according to inflow from linked waste water's distribution ration. As a result of modeling through various scenarios, it was found that the increment of TN and TP were at the least when the inflow of linked water was distributed with ratio between sewage (80%) and oxygen-free tank (20%).

• Journal of Environmental Impact Assessment
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• v.22 no.1
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• pp.1-17
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• 2013

Carbon sequestration on soil is one of the counter measurements against climate change in agricultural sector. Increasing incorporation of organic fertilizer would increase soil organic carbon (SOC) but it could bring high potential of nutrient losses which would result in water quality degradation. In this paper, literature review on soil organic carbon behavior according to agricultural management is presented. The results of field experiment to identify the effect of organic and commercial fertilizer applications on SOC and runoff water quality were also presented. Field experiment confirmed increased SOC and nutrient concentrations in runoff water as application rate of organic fertilizer increase. The potential use of simulation model to develop best agricultural management practice considering carbon sequestration and water quality conservation at the same time is discussed and monitoring and modeling strategies are also suggested to achieve the goal.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.1
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• pp.101-112
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• 2007

This study has used RMA2 model and RMA4 model, which are depth-averaged two-dimensional flow and water-quality prediction models, to analyze the variation of the water-quality by the gates operation in the Seonakdong River. Sensitivity analysis is performed to get the Manning coefficient and the coefficient of eddy viscosity for RMA2 model, and to get the diffusion coefficient for RMA4 model. Since the numerical simulation using RMA2 and RMA4 models did not consider tributary pollutant load except for that of Joman River, it could make a little difference from the natural phenomenon. Nevertheless, the numerical simulation shows that the discharge of $30m^3/s$, which is the continuous inflow from the Daedong-gate, can make it possible to achieve the target water-quality (BOD 4.3mg/L) of Nakbon-N watershed about 10 days later if the Daejeo-gate could remain opened in connection with the Noksan-gate operation.

• Water for future
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• v.29 no.3
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• pp.177-186
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• 1996

QUAL2E model was applied to assess the water quality variations due to dredging of the bottom deposit in the downstream of the Nakdong River. A variedflow analysis was performed for the reach of Namji to Nakdong Estuary to estimate the hydraulic parameters. BFGS (Broyden-Fletcher-Goldfarb-Shanno) method was applied to determine the optimum reaction parameters and model verrification was performed based on these. Water quality modeling of dredging effects for BOD and DO in the reach was performed under low and average flow conditions and alternatives. It revealed that dredging had significant effedcts on the improvement of water quality in the reach.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.19 no.3
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• pp.253-261
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• 2001

Nowadays, various water quality prediction models have been studied, then these models can support the method which evaluate the effect of various alternative water quality management by simulation without experimentation. But, It is necessary to create complex input data file for applying these water quality model and even though the appropriate result is extracted, it is impossible to use as decision making data effectively because of the limitation of expression of model itself. As this study is about the stream water quality modeling, for overcoming the model's above limitation, by developing an interface which can calculate the pollutant load of watershed, I could create a input data file and visualize the simulation result so that I was going to integrate water quality model and GSIS using Flexible coupling applied to GSIS in the pre-process and post-process on model. The QUAL2E model, used in this study, is verified by stream water quality model in previous various results of study and has many examples through previous study, because that is appropriate to water quality model, especially in Korea, and comparatively accurate and their usage is quite simple.