• Journal of Wetlands Research
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• v.21 no.1
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• pp.77-83
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• 2019

Stream water qualities have been predicted in the year 2002 and 2014 through providing the Hwangguji Stream Rectification Plan. However, the reliability of result for predicted water quality was relatively lower by applying conventional values of the parameters in model. In this study deoxygenation coefficients between Sema bridge(HGJ2) and Sujik bridge(HGJ3) have been evaluated based on the observed data of water quality and travelling time to compare with the applied value of coefficients in predicting water quality model. The values of deoxygenation coefficient $0.078day^{-1}{\sim}0.748day^{-1}$ for normal period and $0.053day^{-1}{\sim}0.505day^{-1}$ for drought period have been calculated based of observed data between Sema bridge and Sujik bridge. The values of coefficients $0.02day^{-1}{\sim}3.4day^{-1}$ have been applied in predicting water quality model in the year 2002 and $0.043day^{-1}$ 2014. Thus, the simulated results of stream water quality were better than the observed data in 2002, and worse in 2014. It has shown that values of deoxygenation coefficient should be properly estimated based on observed data to predict proper stream water quality by model.

• Water for future
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• v.17 no.2
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• pp.85-97
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• 1984

Measuring the river flow and water quality in the midstream of the Nakdong River, the natural purification status in examined through the analyses of the elements which affect the variation of dissolved oxygen, and DO model is evaluated to the midstream reach of the river. The major results of this study are as follows; the pruification factor of the of the river is relatively high, it is worried over eutrophication considering much production of algae, and it is evaluated that important factor affecting the DO value computed by the proposed DO model are in order of reaeration coefficient, carbonaceous BOD and deoxygenation constant.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.20 no.1
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• pp.69-78
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• 1987

Human wastes are rich in organic matter and therefore affect the dissolved oxygen when they are discharged into the sea. The breakdown of this organic matter liberates nutrients. The purpose of this study is to evaluate the self-purification capacity in the southern waters of the East Sea during the three cruises in June, July and August, 1986. Streeter and Phelps' model has been used in this study. Factors in this model, deoxygenation constant and reaeration coefficient, have been determined by applying oxygen consumption method and a closed system model. Deoxygenation constant and reaeretion coefficient are 0.177-0.313/day and 0.025-0.364/day respectively. The self-purification capacity to the DO value of 5mg/l is found to be $42.29\~434.25g\;BOD/m^2$, and to a great extent depends on the vertical mixing.

• Journal of Korean Society on Water Environment
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• v.28 no.2
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• pp.178-184
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• 2012

BOD decay rate is a key parameter of BOD-DO models in streams and lakes. In the calibration of water quality modeling appropriate range of coefficient is required for guidance of parameter selection. In this study BOD decay rate was measured at 48 stream sites and 10 reservoir sites in 8 different river systems. The decay rate ranged from 0.09 to 0.25 $day^{-1}$ with a mean of 0.16 $day^{-1}$. Among river systems the decay rates showed significantly different ranges, with the Han River system showing higher values than other river systems. In comparing different types of water bodies, the decay rate was slightly higher in tributaries than in reservoirs and mainstreams. Our results can provide guidance to the selection of proper coefficient for various water bodies in the calibration of water quality models.

• Journal of environmental and Sanitary engineering
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• v.14 no.4
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• pp.77-84
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• 1999

Most river quality problems are generated by pollutants which are discharged into the river as a consequence of human activities. And eutrophication occurs when water is over enriched with nutrients, principally nitrate and phosphate. Both these nutrients are found in many waste products, especially sewage even when the waste is treated. Eutrophication is concerned in lakes, but it also causes problems in river. Wide growth of Phytoplankton in rivers, leads to blockage of channels, but the main concern is deoxygenation because of the increase in plant life's demand for oxygen in revers. Fish, plant and animals die due to lack of oxygen. The increase of algae floating on the tops of water looks ugly and has attracted public attention and concern in recent years. One way of controlling eutrophication is to restrict the amount of waste carrying nitrate or phosphate from entering the water in the first place. another way is to remove it from the water after it has been entered. This study was carried out to investigate on the trophic state, nutrients and Chlorophyll-a concentration in the Han River. The results were as follows:1. Concentrations of total nitrogen were 2.208~9.221(5.133)mg/$\ell$2. Concentrations of total phosphate were 0.045~0.614(0.195)mg/$\ell$3. Chlorophyll-a concentration were $0.0-25.3(9.6)mg/m^3$.4. The correlation coefficient between T-P and Chlorophyll-a concentration was r=-0.856 at Sungsan sampling site.5. The correlation coefficient was r=-0.578~-0.767, between Paldang Dam outflow and Chlorophyll-a concentration at all sampling sites.

• Journal of the Korean GEO-environmental Society
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• v.4 no.3
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• pp.69-77
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• 2003

This study was carried out to evaluate the WASP5 model parameters and to analyze the sensitivity of parameters in Daechung Reservoir. The values predicted by the model and tendency were very similar to the observed data at Daejeon intake, so it is possible to predict water quality of the Daejeon intake region in the future. Results from the sensitivity analysis showed that Chlorophyll-a was sensitive to variations in saturated growth rate of phytoplankton, endogenous respiration rate of phytoplankton, extinction coefficient and temperature. T-N was sensitive to mineralization rate of dissolved organic nitrogen and temperature. T-P was affected by T-P load, temperature, extinction coefficient, mineralization rate of dissolved organic phosphorus and saturated growth rate of phytoplankton. BOD was influenced by deoxygenation rate and temperature, and DO was influenced by temperature. Adequate input data was applied and assessed through the model sensitivity analysis. So it is possible to distinguish the input data which need careful attention when it has application to model.

• Journal of Korean Society on Water Environment
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• v.21 no.5
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• pp.511-515
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• 2005

CBOD(carbonaceous BOD) decay rate was investigated for the execution of water quality model in Nakdong-Rive basin. Estimation of laboratory-derived CBOD decay rate, $k_l$ and CBOD decay rate in natural waters, $k_d$ were carried out. Hydraulic factors were applied for the calculation of $k_d$. Values of biochemical oxygen demand were investigated in Weagwan, Koreong, Jeokpo, Namgi and Mulgeom sites for the four times. The ranges of $k_l$ value were $0.04{\pm}0.01{\sim}0.14{\pm}0.03$. The values of $k_l$ in upstream sites were much larger than those in the downstream sites. The values of $k_d$ were 0.025, 0.036, 0.005 and 0.001 at Weagwan, Jeokpo, Namgi and Mulgeom, respectively, indicating that values of $k_d$ were generally larger than those of $k_l$.