• Journal of Environmental Science International
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• v.28 no.12
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• pp.1071-1083
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• 2019

In this study, water quality levels were classified and water quality indices were calculated and analysed by using the water quality components of living environmental standards monitored 10 years (2008 ~ 2017) at four stations in the West Nakdong River. As a result of analyzing the monthly variation of the water quality components of the living environmental standards, the water quality in the West Nakdong River was worse downstream than upstream, and pollution at the WNR3 located in the downstream of the Jomangang was the most serious. As a result of classification of water quality levels, BOD and COD levels were the lowest, so water quality pollution in the West Nakdong River was found to be highly influenced by organic matters. The water quality index was the lowest in July and August at four stations, so water quality is showing the worst in summer. As a result of analyzing the correlation between the water quality components and the water quality index, the correlation between the TOC and the water quality index was high in the four stations, and the water quality index in the West Nakdong River was dominated by organic matters and nutrients.

• Journal of Environmental Health Sciences
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• v.9 no.1
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• pp.15-30
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• 1983

The stochastic analysis was carried out to the hourly time series observed at Dae-gu, Wha-Myung and Ku-Mee in order to see water quality variation of the Nack-Dong River during Three months (July, Aug. and Sept.) in each year of 1979 and 1981. As a result of this study, it was found that 1. The simple correlation coefficients between some of the variables were fairly high. For example, the coefficients between Do and WT. were -0.824 (Dae-gu), -0.547 (Wha-myung), and -0.911(Ku-mee). The coefficients between COND and DO. were -0.263(Dae-gu), -0.347(Wha-myung) and -0.881 (Ku-mee). The coefficients between COND and WT. were 0.531 (Dae-gu), 0.361 (Wha-myung) and 0.800 (Ku-mee). 2. Hourly water quality time series of WT and DO existed as dominant 24 hours Periodicity For example, the Aut correlation coefficients about WT were 0.960 (K=1), 0.846(K=24), 0.691(K=48), 0.596(K=72), and 0.453(K=96). The auto-correlation coefficients of Do were 0.968 (K=1), 0.591 (K=24), 0.393 (K=48), 0.349 (K=72) and 0.250 (K=96). 3. Weekly water quality time series of WT and Do varied with the dominant 24 hours periodicity.

• Journal of the Korean Society for Marine Environment & Energy
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• v.4 no.3
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• pp.28-39
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• 2001

The eco-hydrodynamic model was used to simulation water quality of Kwangyang Bay according to the environmental variation for appropriate water quality management. The mean concentration of COD was 3.3㎎/L, this exceeded the third class of water quality criteria. Waste water discharging loads showed approximately 90% of total pollutant loads. For satisfaction to below 10㎍/L of Chl. a and 2㎎/L of COD, above 35% reduction of present pollutant loads of point sources are needed.

• Journal of Korean Society on Water Environment
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• v.38 no.1
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• pp.1-9
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• 2022

The Yeongsan River, one of the four major rivers in Korea, shows the highest degree of water pollution compared to the other major rivers. The construction and opening of two weirs, Seungchon and Juksan, induced fluctuations in the hydrologic conditions and water quality of the river. To investigate the water quality changes caused by the opening of the weir in 2017, this study analyzed the water quality data using the non-parametric Wilcoxon signed-rank test and the three-dimensional spatiotemporal plots. The non-parametric statistical test results showed that the concentration of all parameters has increased after 2017 at a significance level of 0.05. For the parameters that showed the highest degree of change, chlorophyll-a and suspended solids, the median values have increased by more than 30% after weir opening. Visual analysis additionally showed the spatial changes in the Yeongsan River. Generally, the sites above the Seungchon weir showed higher pollution levels than those above the Juksan weir. In time series, visual analysis results also showed the trend of rising concentration for all water quality parameters, indicating that the opening of two weirs had a significant effect on the change in water quality of the Yeongsan River.

• Journal of Korean Society on Water Environment
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• v.22 no.6
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• pp.1144-1150
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• 2006

Recently, as water pollution accidents in rivers have increased, there is an increased interest in water quality forecast with accurate simulation. QUAL2E model, widely used for water quality analysis, uses the same hydraulic characteristics, such as depth and velocity, in a reach. The flow of the river is changed by various hydraulic constructions or by topography in a real river channel. In this study, a hydraulic connection module is developed to consider flow variations of river channels in QUAL2E model. The module uses the simulations results of non-uniform flow of a 1-D hydraulic model such as DWOPER or HEC-RAS. The improved QUAL2E model with this module was applied to a downstream section of Paldang Dam on the Han River. The results show the variation of water quality very well in a reach where flowing vary abruptly, like the Jamsil submerged weir.

• Water for future
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• v.14 no.3
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• pp.55-66
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• 1981

The theory and practice of water quality scoring and indexing are introduced. The monthly water analysis data are available for six stations long the down-stream Han River whthin the areal boundary of the Special City of Seoul. The data cover the period between 1975 and 1979 inclusive and contain the analytical findings on 37 water constituents including DO, BOD, temperature, total solids and etc. Sic parameters are selected form the 37 items, that, to the judgement of the writer, best reflect the water quality of the Han River. They are; dissolved oxggen saturation, pH, fecal coliform, total solids, BOD and nitrate+ammonia. For each of the six parameters, a subscore function is developed and graphically presented to facilitate the transform of a measurment of the arameter to a subscore on a common score(e.G. 0-100) The score of a sample is calculated as a fuction of the six subscores, using four different approaches; (1) the unweighted arithmetic water quality score, (2) the weighted arithmetic water quality score, (3)the unweighted multiplicative score and (4) the reduced (total) score. Independent of these calculated scores, the experts' score which is calculated by averaging the ratings of water quality experts is obtained and compared with each of the four calculated scores by means of the least square method. The experts' score compares most favorably with the "reduced" score with the correlation coefficient of 0.956 : therefore this method of water quality scoring is adopted to calculate the Han River water quality scores and indices. Water quality index data for Guiri, ukdo, Pokwangdong, Noryangjin, Yongdungpo and Kayang Stations, 1975-1979 are as follow: The overall water quality index data of the Han River between Guiri and Kayang Stations are found; 47.3 in 1976, 48.0 in 1977, 48.5 in 1978 and 54.7 in 1979, indicating the general trend towards water quality improvent in this part of the river, in terms of the increased water quality index by average 1.85 points per year during this period. Finally the optimum sampling frequencies distributed among the six stations, using an equation which takes into account the coefficients of variation of the water quality scores and indices arec calculated.alculated.

• Journal of Preventive Medicine and Public Health
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• v.23 no.1 s.29
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• pp.106-116
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• 1990

This study was conducted to investigate of water qualities in the upper and middle reaches of the Han River. For this purpose, water was sampled at Kwangjin and 1st Han-River Bridges of the Han River in Seoul and analysed from August, 1988 to September, 1989. The results are summarized as follows : 1. Water quality at 1st Han-River Bridge was more polluted than that at Kwangjin Bridge. 2. Except biological oxygen demand (BOD), turbidity, suspended solid (SS), dissolved oxygen (DO), DO saturation (DOS), ammonia nitrogen ($NH_3-N$), nitrite nitrogen ($NO_2-N$) and chloride ion ($Cl^-$) at Kwangjin and 1st Han-River Bridges were lower as compared with the previous data before redevelopment of the Han River. 3. SS, DO and pH at Kwangjin and 1st Han-River Bridges could be classified to the 1st grade in environmental water quality standard. DOS at Kwangjin Bridge was over 100% and that at 1st Han-River Bridge was below 100% in the Han River. BOD at Kwangjin Bridge could be classified to End grade and that at 1st Han-River Bridge to 3rd grade in environmental water quality standard. 4. The higher the level of water was, the lower the levels of turbidity and SS, and $NH_3-N$ was decreased with increasing water level at 1st Han-River Bridge. DO was decreased as water temperature went up but DOS was increased with DO. BOD was positively correlated with nitrite-nitrogens. 5. Turbidity and SS at the both sites and Chloride ion ($Cl^-$) at Kwangjin Bridge were increased in July and August. And DO at the both sites and $NH_3-N$ at 1st Han-River Bridge were decreased in at July and August.

• Journal of Korea Water Resources Association
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• v.35 no.4 s.129
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• pp.385-395
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• 2002

A stochastic model using FOEA(First-Order Error-Analysis) and Monte Carlo Method is developed to predict water quality variation in a river. A sensitivity analysis using influential matrix is performed to determine the significant reaction coefficients. Also the BFGS (Broyden-Fletcher-Goldfarb-Shanno) optimization method is applied to estimate the optimal values of the major reaction coefficients. The developed stochastic model is applied to the real study reach and the results are agreed well with those of deterministic analysis. The process for analyzing the uncertainties of the discharge, water quality and reaction coefficients of headwater and tributaries is included in the model to estimate the influence on the water quality variation at downstream. The extents of contribution of the uncertainties influencing on the total uncertainty can be evaluated from the results of the model.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2002.05a
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• pp.81-84
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• 2002

Recently Bentonite mat is applied various structure : External waterproofing for underground structure, A reclaimed land, Artificial lake, Large-scaled civil structure, etc. With these various structure environment, water quality for application of Bentonite Mat affects watertightness. Specially spot with a large quantity of Chloride ion like salt water, degree of watertightness revelation is evaluated and applied. In this study, it is a main goal to investigate watertightness of Bentonite Mat with distilled water and salt water dissolved chloride ion Contents 0.88%. The result of this paper is as follows. 1) Water permeability coefficient of Bentonite Mat : distilled water(1.21$\times$10$^{-9}$cm/sec), salt water(3.12$\times$10$^{-7}$cm/sec). 2) Variation of thickness : distilled water(187%), salt water(108%). 3) Swelling ratio : distilled water(1500%), salt water(350%).

• Journal of Korean Society on Water Environment
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• v.39 no.5
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• pp.377-389
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• 2023

Chungcheongnam-do has been measuring the flow rate and water quality of streams in the province once a month since 2011 in order to water environment policies. Based on the results, after evaluating the coefficient of variation and the tendency of the water quality trend by using the Mann-Kendall test and Sen's Slope for each stream, the streams subject to priority introduction of Total Pollution Load Management at Tributaries were selected through the Stream Grouping Method. The water quality trend analysis results for 125 streams using the Mann-Kendall test and Sen's Slope were evaluated as streams showing a tendency of deteriorating water quality Biochemical oxygen demand (BOD): 13 streams, Total Phosphorus (T-P): 16 streams). Streams with deteriorating water quality were classified into A-D groups using the Stream Grouping Method. Group A, which has a high flow rate and high water quality, is a stream that requires priority management, and was selected as a stream for introduction of Total Pollution Load Management at Tributaries. There are 7 streams that need to be introduced into the BOD category, and there are 7 streams that need to be introduced into the T-P category. In this study, based on flow and water quality monitoring data accumulated over a long period of time (2011-2022), statistical techniques are used to select watersheds in which water quality is deteriorating. Accordingly, it is expected that it will be useful in establishing a water quality improvement plan in the future.