• Journal of environmental and Sanitary engineering
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• v.17 no.4
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• pp.1-9
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• 2002

In order to define about concern with discharge and water-quality, it is calculated drought flow, low flow, normal flow and wet flow in Chungju watershed from flow duration analysis. Water quality modeling study is performed for forecasting at upstream of Chungju lake. It is devided method of modeling into before and after the equipment of environmental treatment institution. And it is estimated the change of water quality. Before the equipment of environmental treatment, BOD concentration is increased from 23000 to 2006 years at all site and decrease on 2012 years. The rate of increasing BOD concentration is showed height between 2000 years and 2003 years most of all site. And after the equipment of environmental treatment, it is showed first grade of BOD water quality in most of sample site beside Jucheon river. The result of water quality modeling using drought flow showed that a lot of pollution occurred. And water quality using wet flow is good, so much discharge make more improve water quality than little discharge.

• Advances in environmental research
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• v.6 no.1
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• pp.53-65
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• 2017

Assessment of seasonal changes in surface water quality is an important aspect for evaluating temporal variations of river pollution due to natural or anthropogenic inputs of point and non-point sources. In this study, surface water quality data for 15 physico-chemical parameters collected from 7 monitoring stations in a river during the years from 2014 to 2016 were analyzed. The principal component analysis technique was employed to evaluate the seasonal correlations of water quality parameters, while the principal factor analysis technique was used to extract the parameters that are most important in assessing seasonal variations of river water quality. Analysis shows that a parameter that is most important in contributing to water quality variation for one season may not be important for another season except alkalinity, which is always the most important parameters in contributing to water quality variations for all three seasons.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.3
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• pp.305-314
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• 2007

Forecasting of water quality variation is not an easy process due to the complicated nature of various water quality factors and their interrelationships. The objective of this study is to test the applicability of neural network models to the forecasting of the water quality at Dalchun station in Han River. Input data is consist of monthly data of concentration of DO, BOD, COD, SS and river flow. And this study selected optimal neural network model through changing the number of hidden layer based on input layer(n) from n to 6n. After neural network theory is applied, the models go through training, calibration and verification. The result shows that the proposed model forecast water quality of high efficiency and developed web-based water quality forecasting system after extend model

• Water Engineering Research
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• v.2 no.2
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• pp.103-112
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• 2001

Issues and problems in formulating South Korea's water resources policy are discussed in terms of water quantity and quality. South Korean needs both water conservation and water supply capability for the growing population and economic activities. The government has attempted to build more large-scale dams to store and supply water for residential, farming and industrial uses, but the environmentalists who emphasize conservation and environmental protection oppose the government. The environmentalists are popular among the general public. Water quality has been deteriorating from point- ad non-point sources. urban and farm runoffs are serious pollutants. All want by preserve water quality. There is no dispute on this matter between the government and the environmentalists. Money is hard to come by to preserve water quality. Economic and financial crises and no self-sufficient local governments' revenue structure are pessimistic. Basic survey on water resources, hydrology and hydraulic is badly needed for the future water resources planning.

• Journal of Korean Society on Water Environment
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• v.20 no.4
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• pp.321-326
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• 2004

The objective of this study is to test the applicability of neural network models to forecast water quality at Naesa and Pyongchang river. Water quality data devided into rainy day and non-rainy day to find characteristics of them. The mean and maximum data of rainy day show higher than those of non-rainy day. And discharge correlate with TOC at Pyongchang river. Neural network model is trained to the correlation of discharge with water quality. As a result, it is convinced that the proposed neural network model can apply to the analysis of real time water quality monitoring.

• Journal of Korean Society on Water Environment
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• v.37 no.3
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• pp.175-189
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• 2021

In this study, 48 streams in the Sapgyo Watershed were selected, and the Load Duration Curves (LDC) were drawn up for each stream using water quality and flow monitoring over the last three years (2018-2020), and it was evaluated whether the target water quality was achieved for each flow section. As a result of evaluating whether or not the target water quality exceeded according to the LDC, it was found that 22 rivers exceeded the target water quality. Five rivers exceeded the target water quality due to point pollutant sources, 13 rivers exceeded the target water quality due to non-point pollutant sources, and 4 rivers exceeded the target water quality due to both point and non-point pollutant sources. Among the rivers that exceeded the target water quality due to point pollutant sources, which included domestic sewage of the untreated population, there is a need to reduce the influx of polluted loads by the untreated population. The use of eco-friendly fertilizers is recommended for rivers with a relatively high farmland ratio among rivers exceeding the target water quality due to non-point pollutant sources, and installation of boiling point reduction facilities that can reduce the amount of polluted load introduced during rainfall or manage water shores. In rivers with a large number of livestock breeding heads, the livestock houses located in these rivers need to be preferentially transferred to livestock manure treatment plants. Due to the high ratio of land area because of urbanization, initial rainwater treatment facilities are required to reduce the amount of pollutant load flowing into the river through the impermeable layer during rainfall.

• Journal of Korean Society on Water Environment
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• v.22 no.5
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• pp.784-795
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• 2006

The purpose of this study was to assess biological river water quality by using epilithic diatoms at 40 selected sites in Geum, Youngsan, and Seomjin River systems. The sampling and analyses were performed during three seasons including January, April and June in 2005. Various water quality parameters also were analyzed. We attempted to classify the water quality condition by epilithic diatom indices (DAIpo and TDI) with the results of corresponding analyses of various chemical water quality parameters. A five class system was delivered to describe the water quality condition ranged from "very good" to "very poor." We also proposed a way of classifying water quality condition by combining two diatom indices of DAIpo and TDI. Our results showed that biomass of epilithic diatoms varied not only seasonally but spatially; it was not likely that winter diatoms represent average water quality condition, due to high concentration of nutrients. Water quality status assessed by diatom indices was generally worse than that assessed by BOD, indicating that BOD standard likely underestimates the biological condition of the water body. Importantly, nutrient-based diatom index (TDI) generally overestimated organic matter-based index (DAIpo) at most study sites, indicating that diatoms in studied rivers were likely more affected by nutrients than organic matter. Thus, management strategy to improve river water quality in Korea is suggested to emphasize more on the nutrients than organic matters.

• Journal of Wetlands Research
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• v.24 no.4
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• pp.256-267
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• 2022

This study analyzed the current status and trend of water quality using long-term water quality monitoring data measured over the past 5 years in the Seohwacheon Basin, located upstream of Daecheong Lake. In the Seohwacheon Basin, a project is underway to reduce the occurrence of algal blooms in the Daecheong Lake and to improve water quality, and continuous management is required for water quality management. The current water quality evaluation aims to identify the water quality management point, and the good water grade and the integrated water quality index (WQI) were used. For trend evaluation, the effect of the water quality improvement project was evaluated using the Mann-Kendall test and Sen's Slope. As a result of the evaluation, the current water quality index was used to identify the watersheds and when to manage water quality, and the effect of the improvement project was confirmed through trend analysis. Through this study, it is possible to review the water quality status and improvement effect using long-term water quality monitoring data, so it is expected to be applicable to similar types of watersheds in the future.

• Journal of Korean Society on Water Environment
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• v.31 no.6
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• pp.723-731
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• 2015

We investigated the spatial and temporal patterns of water quality in the Gangjung-Goryoung weir that is located in the middle area of the Nakdong river, Korea. The monitoring results indicated that there are discernible vertical differences in water quality during the pre- and post-monsoon periods (May to September). During this period, it was observed that the weak thermal stratification formed at the maximum level, and pH, Chl-a, and DO concentrations in the surface layer were higher than those in the bottom layer. This vertical difference was especially noticeable for DO concentrations: there were DO depletions at the bottom layer in late June to early August. During the summer monsoon period with heavy rainfall, there was a decline in vertical differences in water quality. From this study, it was suggested that continuous monitoring of vertical profiles could become a useful tool for identifying the spatial and temporal distributions of water quality and for developing the best management policy for water quality in the Nakdong river.

• Journal of Korean Society of Water and Wastewater
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• v.25 no.3
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• pp.313-324
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• 2011

Several complaints from consumers on red or turbid waters were often filed at the same places although various efforts were made to improve water quality in the drinking water plant. The red water problems were occurred due to corrosion of main water pipe, especially at extremity. The low concentrations of chlorine indicating poor water quality were detected at the problematic location. To solve the poor water quality at the extremity, flushing techniques, i.e., conventional flushing, unidirectional flushing, and continuous flushing, were recently practiced. In this study, effects of conventional flushing on water qualities were examined by comparing turbidity and residual chlorine before and after flushing. In addition, more detailed analyses on water qualities at the tap water were conducted to learn a reduction pattern during flushing. Five items from geographic information system of water distribution were used to obtain a relationship with water quality, washing duration or amounts of washing water. The flushing was effective to meet the National Drinking Water Quality Standard with simple and relatively short time operation. The key operational parameter in flushing was amounts of washing water which should be estimated based on water quality of the consumer's tap water. The positive relationship between the residual chlorine and pipe length implied that detention time in the pipeline was the main cause of the complaints. More experiments on effectiveness of flushing are needed to determine reasonable strategies of flushing.