• 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.

• 한국습지학회지
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• 제19권3호
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• pp.311-317
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• 2017

본 연구에서는 낙동강수계에서의 수질 모니터링 자료를 이용하여 수질지수를 산정하고 생활환경기준과 비교를 통해 수질상태를 검토하였다. 수질지수는 환경부에서 현재 시행되고 있는 실시간수질지수(RWQI) 방법인 CCME-WQI을 사용하였으며 수질항목은 pH, DO, EC, 수온, TOC, T-N, T-P에 대해 7개 평가항목으로 선정하였다. 평가기간은 최근 3년간(2013년~2015년)으로 선정하였으며 해당 기간 내 측정된 수질 모니터링 자료를 이용하였다. 평가결과, 전 기간 평가 결과는 지수와 생활환경기준이 비슷한 경향을 보이나 월별 평가는 지수와 BOD, T-P 결과가 다르게 나타났다. 따라서 효율적인 하천관리를 위해서는 단일 수질항목만의 평가보다 복합적인 평가가 보다 필요할 것으로 신뢰성이 있는 것으로 검토되었다.

• 한국수자원학회논문집
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• 제44권6호
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• pp.439-447
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• 2011

This study aims to test the feasibility of combined use of EFDC (Environmental Fluid Dynamics Code) hydrodynamic model and WASP7.3 (Water Quality Analysis Program) model to improve accuracy of water quality predictions of the Yongdam Lake, Korea. The orthogonal curvilinear grid system was used for EFDC model to represent riverine shape of the study area. Relationship between volume, surface and elevation results were checked to verify if the grid system represents morphology of the lake properly. Monthly average boundary water quality conditions were estimated using the monthly monitored water quality data from Korean Ministry of Environment DB system. Monthly tributary flow rates were back-routed using dam discharge data and allocated in proportion to each basin area as direct measurements were not available. The optimum number of grid system was determined to be 372 horizontal cells and 10 vertical layers of the site for 1 year simulation of hydrodynamics and water quality out of iterative trials. Monthly observed BOD, TN, TP and Chl-a concentrations inside the lake were used for calibration of WASP7.3 model. This study shows that EFDC and WASP can be used in series successfully to improve accuracy in water quality modeling. However, it was observed that the amount of data to develop inflow water quality and flow rate boundary conditions and water quality data inside lake for calibration were not enough for accurate modeling. It is suggested that object-oriented data collection systems would be necessary to ensure accuracy of EFDC-WASP model application and thus for efficient lake water quality management strategy development.

• 한국물환경학회지
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• 제27권5호
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• pp.689-698
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• 2011

In South Korea, Total Maximum Daily Load (TMDL) has been enforced since 2004 to restore and manage water quality in the watersheds. However, the appraisal of TMDL in South Korea has lots of weaknesses to establish the plan for recovery of water quality because it just evaluates the target water quality during the particular flow duration interval. In the United States, Load Duration Curve (LDC) method bas been widely used in the TMDL to evaluate the water quality and pollutant loads considering variation of stream flow. In a recent study, web-based Load Duration Curve system was developed to create the LDC automatically and provide the convenience of use. In this study, web-based Load Duration Curve system was applied in the Gapyeongcheon watershed using the daily flow and 8-day interval water quality data, and Q-L Rating Curve was used to evaluate the water quality and pollutant load in the watershed, also. As a result of study, water quality and pollutant load in Gapyeongcheon watershed were met with water quality standard and allocated load in the all flow durations. Web-based Load Duration Curve system could be applied to the appraisal of South Korean TMDL because it can be used to judge the impaired flow duration and build up the plan of load reduction, and it could enhance the publicity. But, web-based Load Duration Curve system should be enhanced through addition of load assessment tools such as Q-L rating curve to evaluate water quality and pollutant load objectively.

• 농업과학연구
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• 제49권2호
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• pp.193-202
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• 2022

The recurrent neural network (RNN) algorithm has been widely used in water-related research areas, such as water level predictions and water quality predictions, due to its excellent time series learning capabilities. However, studies on water quality predictions using RNN algorithms are limited because of the scarcity of water quality data. Therefore, most previous studies related to water quality predictions were based on monthly predictions. In this study, the quality of the water in a reservoir in Nonsan, Chungcheongnam-do Republic of Korea was predicted using the RNN-LSTM algorithm. The study was conducted after constructing data that could then be, linearly interpolated as daily data. In this study, we attempt to predict the water quality on the 7th, 15th, 30th, 45th and 60th days instead of making daily predictions of water quality factors. For daily predictions, linear interpolated daily water quality data and daily weather data (rainfall, average temperature, and average wind speed) were used. The results of predicting water quality concentrations (chemical oxygen demand [COD], dissolved oxygen [DO], suspended solid [SS], total nitrogen [T-N], total phosphorus [TP]) through the LSTM algorithm indicated that the predictive value was high on the 7th and 15th days. In the 30th day predictions, the COD and DO items showed R² that exceeded 0.6 at all points, whereas the SS, T-N, and T-P items showed differences depending on the factor being assessed. In the 45th day predictions, it was found that the accuracy of all water quality predictions except for the DO item was sharply lowered.

• 한국물환경학회지
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• 제23권5호
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• pp.697-704
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• 2007

This study proposes an integrated technique of Genetic Algorishim (GA) and Geographic Information System (GIS) for designing the water quality monitoring networks. To develop solution scheme of the integrated system, fitness functions are defined by the linear combination of five criteria which stand for the operation objectives of water quality monitoring stations. The criteria include representativeness of a river system, compliance with water quality standards, supervision of water use, surveillance of pollution sources and examination of water quality changes. The fitness level is obtained through calculations of the fitness functions and input data from GIS. To find the most appropriate parameters for the problems, the sensitivity analysis is performed for four parameters such as number of generations, population sizes, probability of crossover, and probability of mutation. Using the parameters resulted from the sensitivity analysis, the developed system proposed 110 water quality monitoring stations in the Nakdong River. This study demonstrates that the integrated technique of GA and GIS can be utilized as a decision supporting tool in optimized design for a water quality monitoring network.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2004년도 학술발표회
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• pp.563-567
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• 2004

During drought season, the self-purification capacities of the four major rivers in Korea are significantly controlled by environmental maintenance flows supplied from the mid- or upstream large dams. Therefore, it is obviously important to operate the dams considering not only water quantity aspects but also conservation of downstream water quality and aquatic ecosystems. Mathematical water quality models can be efficiently used to serve as a decision support tool for evaluating the effects of operational alternatives of upstream dams on the downstream aquatic environment. In this study, an unsteady one-dimensional water quality model, KORIV1-WIN was developed based on the theoretical and numerical algorithms for hydrodynamics and water quality simulations of CE-QUAL-RIV1. It consists of hydrodynamic(KORIV1H) and water quality(KORIV1Q) modules, and pre- and post-processors for input data preparations and output displays. The model can be used to predict one-dimensional hydraulic and water quality variations in rivers with highly unsteady flows such as dam outflow change, rainfall-runoff, and chemical spill events.

• 한국환경보건학회지
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• 제30권2호
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• pp.98-103
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• 2004

To evaluate the quality of drinking water and contamination sources in a rural community, this study was carried out on the summer of 2003 at Shin-Dong Myun, Chun-Cheon, Gang-Won province. Seventy three drinking water samples were collected from three different types of water supply systems. Sources of contamination were identified and the public perception of water quality area were evaluated. The findings of this study are as follows; Drinking water was mainly obtained from Local Water and Simple Piped Water Supply Systems, and pollution sources varied over the study area. Most of residents (＞63%) were satisfied with the quality of drinking water and could not identify any contamination sources. Corresponding to this perception, measured water quality parameters generally met the Drinking Water Quality Standards (＞64%). However, approximately 35.6% of samples exceeded the regulation for Nㅒ$_3$$^{-}$$_{-}$N, coliform, and general bacteria. The water quality was significantly different among the three water supply systems, and between the potentially contaminated areas and the rest of the areas (p＜0.05). In the potentially contaminated areas, the levels of coliform and general bacteria contamination were significantly higher than the rest of the areas (p＜0.05). The coliform and general bacteria values of Simple Piped Water were significantly higher than Own Piped Water＇s, and the NO$_3$$^{-}$$_{-}$N values of Own Piped Water were significantly higher than those of water＇s (p＜0.05). Based on this study, NO$_3$$^{-}$$_{-}$N, coliform, and general bacteria were identified as a major problem of drinking water. To regularly manage drinking water supply systems, to identify contamination sources, and to add drainage systems are required in the study area.

• Environmental Analysis Health and Toxicology
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• 제6권1_2호
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• pp.1-6
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• 1991

The quality of water in Kyungan stream was analyzed in three different areas between season of irrigation on May and of nonirrigation on august in 1990. The results of Water quality from this study were summarized as follows: 1. The quality of water is season of irrigation containing metal ions, such as Cu and Zn as well as TN was exceeded standard levels of quality of agricultural water However, in season of nonirrigation, the quality of water in Kyungan stream was not suitable for using agricultural water due to over standard levels of containing ions of Cu and Zn or DO, COD and TN. 2. The correlation of water quality exception of pH was shown a reliance when p values were greater than 0.01 for containing ions such as Cu and Zn with the DO, COD and TN. 3. The comparison of water qualities for pH between season of irrigation and season of nonirrigation in Kyungan stream was a considerable significance property when p values were less than 0.05. The water quality containing ions of Cu and Zn with DO, COD, TN and SS also indicated a significant property when p values were less than 0.01. 4. The average water qualities of a year in three different areas for pH have shown a significant property when p values are less than 0.01. The average water qualities of a year containing DO have also shown a significant property having p values of less than 0.05. But other constituents have shown no significant property in the above three different areas.

• 한국물환경학회지
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• 제29권1호
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• pp.36-44
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• 2013

HSPF model based on BASINS was applied to analyze effects of watershed management measures for water quality conservation in the Hwaseong Reservoir watershed. The model was calibrated against the field measurements of meteorological data, streamflow and water qualities ($BOD_5$, T-N, T-P) at each observatory for 4 years (2007-2010). The water quality characteristics of inflow streams were evaluated. The 4 scenarios for the water quality improvement were applied to inflow streams and critical area from water pollution based on previous researches. The reduction efficiency of point and non-point sources in inflow streams was evaluated with each scenario. The results demonstrate that the expansion of advanced treatment system within wastewater treatment plants (WWTPs) and construction of pond-wetlands would be great effective management measures. In order to satisfactory the target water quality of reservoir, the measures which can control both point source and non-point source pollutants should be implemented in the watershed.