• 한국환경과학회지
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• 제19권1호
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• pp.39-45
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• 2010

When the Juam multipurpose dam which is connected with existing large water supply facilities is finished, water environment is changed from stream to lake. The changed quality of water should be examined. In this study, the result of water quality forecasting is analysed and an effective management plan of water quality is presented. Tn this study, the WASPS model that is a dynamic water quality simulation model was selected to forecast the water quality. This model forecasts movement of change of pollutants. For an application of the model, the subject areas were divided into seventeen sub-areas by considering change temperature depending measuring points and on depth of water. Meteorological data collected by the meteorological observatory and data about quality measured by the Korea Water Resources Development Corporation were used for an operation of the model. As a result of quality examination through quality data and estimated pollutant loading, the water quality environment criterion was grade II and the nutritive condition was measured as meso-graphic grade. In this study, an effective management was planned to improve water quality by reducing pollution load. According to the result of examination, when more than 30% of BOD was reduced it was recorded that the environment standard of water quality was improved to the second grade.

• 한국물환경학회지
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• 제22권5호
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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.

• 대한환경공학회지
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• 제32권8호
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• pp.802-808
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• 2010

본 연구는 하천 수질개선을 위해 충청남도 금강 중 하류권역에 위치한 18개의 지류하천을 대상으로 유량 및 수질측정, 하천그룹화, 오염물질 부하량 및 배출부하밀도를 산정하였다. 하천의 수질분석 결과는 저수기의 평균BOD농도를 기준으로 하천생활환경기준 II등급(BOD기준 3.0 mg/L)의 수질을 초과하는 하천은 정안천, 방축천, 길산천, 조천, 석성천, 강경천으로 나타났다. 하천그룹화 결과 금강에 유입되는 유량이 저수량을 기준으로 $10\;m^3/min$ 이상이고, 저수기의 평균BOD 농도가 3.0 mg/L 이상으로 금강의 수질을 악화시키는 주된 요인인 그룹(Group A)에 해당되는 하천으로는 조천, 강경천, 석성천, 정안천으로 나타났다. 이 하천들은 금강의 수질개선을 위해서 수환경관리의 대책을 가장 먼저 고려해야 할 것이다. Group A에 해당하는 하천 중 배출부하밀도가 10 BOD kg/$day{\cdot}km^2$ 정도 이상인 하천은 조천, 석성천, 강경천으로 나타났다. 하천의 유량 및 수질모니터링, 하천그룹화, 배출부하밀도산정 등을 통하여 수질개선 우선순위 유역을 선정한 결과, 연기군의 조천, 부여군과 논산시 경계에 위치한 석성천, 논산시의 강경천과 같은 하천 유역이 수질개선이 시급한 것으로 나타났다.

• 상하수도학회지
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• 제25권3호
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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.

• 한국물환경학회지
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• 제32권2호
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• pp.163-172
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• 2016

This study aimed to develop a plan for effective performance of a watershed through correct identification of a river watershed by using the flowrate of the river and water quality data, which is the basis for the establishment of the water environment policy. The target river for water quality improvement was selected based on the monitoring result for 4 water systems in Chungcheongnamdo province in the recent 3 years. The result of analysis for the distribution of discharge capacity by a pollution source group for the water quality improvement target river showed that most of the target river has a high discharge capacity in the water system for living and livestock. Analysis for the density of the total discharge capacity of the whole watershed of Chungcheongnamdo indicated that the river that needs water quality improvement has high BOD concentration and high discharge load density at the point that this river is located. Thus, for efficient watershed management through selection and concentration, Chungcheongnamdo needs to improve the target river in priority. Stepwise planning is also required to establish and execute the water quality improvement in order to satisfy said target water quality, and establish the index for the water improvement rate for its evaluation.

• 한국물환경학회지
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• 제36권3호
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• pp.245-254
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• 2020

Water quality improvement projects are being implemented without predicting the effect of water quality improvement on Lake Sapgyo. As the method of selecting the target stream for the effective conduct of water quality improvement projects the method of rating the streams were studied. To build a stream grading method, 60 major streams in the Lake Sapgyo system were monitored. The selection method of rivers subject to priority management for water quality improvement was applied to the stream grading method using the Analytic Hierarchy Process (AHP). The analysis of importance by site by stream grading method revealed the following: water quality (36.0%), flow (26.1%), travel load (13.4%), TMDL density (12.0%), TMDL (8.9%), and area (3.7%). The pollution level of the river was scored by using the stream grading method, and the ranking of 51 streams was calculated. Based on this, the group was classified into six grades (A-F). Among the groups, the F and E groups were selected as the priority management streams. Cheonan-Cheon (Cheonan City) was selected as the first stream to establish water quality improvement measures in the Lake Sapgyo system, and Seowoo-Cheon (Dangjin City) was selected as the second site, and Oncheon-Cheon (Asan City) was selected as the third site. Each local government is expected to improve the water quality improvement effect with limited resources when establishing and implementing water quality improvement measures for the streams (F group, E group) to be managed in this study.

• 한국환경과학회지
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• 제16권7호
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• pp.831-838
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• 2007

In order to improve the water environment at urban streams in Korea, several river restoration projects have been initiated for past few years. This study evaluates the impact of diverting water application at the riverhead of Onchun stream through the monitoring program for several water quality and ecological parameters. Various water quality parameters and ecological item such as benthic macroinverterates has been investigated between 09/05 and 12/06. Analysis indicates that the application of diverting water from Nakdong river to Onchun stream distinctly improved several water quality parameters such as, PH, BOD, TN, TP and concentrations of heavy metals. Low flow augmentation also improve ecological indicies such as the diversity index of benthic macroinvertebrates. Generally speaking, releasing addition water from head water of Onchun stream improves various water environmental characteristics.

• 한국물환경학회지
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• 제39권1호
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• pp.46-60
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• 2023

Climate change causes fluctuations in water quality in the aquatic environment, which can cause changes in water circulation patterns and severe adverse effects on aquatic ecosystems in the future. Therefore, research is needed to predict and respond to water quality changes caused by climate change in advance. In this study, we tried to predict the dissolved oxygen (DO), chlorophyll-a, and turbidity of the Paldang reservoir for about two weeks using long short-term memory (LSTM) and gated recurrent units (GRU), which are deep learning algorithms based on recurrent neural networks. The model was built based on real-time water quality data and meteorological data. The observation period was set from July to September in the summer of 2021 (Period 1) and from March to May in the spring of 2022 (Period 2). We tried to select an algorithm with optimal predictive power for each water quality parameter. In addition, to improve the predictive power of the model, an important variable extraction technique using random forest was used to select only the important variables as input variables. In both Periods 1 and 2, the predictive power after extracting important variables was further improved. Except for DO in Period 2, GRU was selected as the best model in all water quality parameters. This methodology can be useful for preventive water quality management by identifying the variability of water quality in advance and predicting water quality in a short period.

• 상하수도학회지
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• 제11권2호
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• pp.40-49
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• 1997

From water management point of view, the industrialization that we have achieved in the last decades brought out two major changes: water shortage and water quality deterioration. They are getting the big obstacles we must overcome to continuously pursue industrialization for further development in the next century. Many plans using dams and advanced treatment methods have been developed for control of quantity and quality, respectively. In this paper, an alternative is conceptually reviewed which is much different from the plans in regard that the alternative looks at system itself. It is based on an interceptor system coupling with a concept of zero-discharge. This system allows no discharge of wastewaters from point-sources to waterbodies which are very sensitive in terms of water quality. In addition reuse of treated effluents is emphasized to a maximum extent. The application of the system to the Nak-Dong river basin indicated that an interceptor system will need from the middle reaches of the basin where industrialization gets heavier. Since wastewaters are not directly discharged to the river, water quality of the down stream will improve. Treated effluents will be able to be reused at a number of industrial complex which currently get water from the Nak-Dong river. This reuse will help alleviate water shortage. The biggest problem anticipated is cost for building and operating such system. A cost-sharing plan among the beneficiaries is considered. Further research is suggested focusing on detailed engineering and technical matters for potential implementation.

• 상하수도학회지
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• 제36권5호
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• pp.289-296
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• 2022

Mangyeong River and Dongjin River are highly dependent on external regions for domestic and agricultural water, and the agricultural water supply and use system of those rivers are very complicated. For smooth water supply, rivers are used as a supply system. Of the total river water use permits (as of 2019), agricultural water accounts for 97.5%, 80.4% in Mangyeong River and Dongjin River, respectively. The excessive intake of river water as agricultural purpose is causing the stream to dry out and to deteriorate the ecological health of the river. It is necessary to minimize the water use system that takes in and utilizes river water. In both rivers, the flow rate of agricultural drainage and the load of major water quality items that flowing into the main stream are similar to or higher than those of the major tributaries, indicating that management is necessary to improve the water quality of the river. It is necessary to understand the effect of agricultural drainage on river water quality by establishing a continuous monitoring system for the form of agricultural drainage.