• Journal of Korean Society on Water Environment
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• v.23 no.5
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• pp.591-599
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• 2007

The quality of water released from a stratified reservoir is dependent on various factors such as the location and shape of intake facility, structure of reservoir stratification, profile of water quality constituent, and withdrawal flux. Sometimes, selective withdrawal capabilities can provide the operational flexibility to meet the water quality demands both in-reservoir and downstream. The objective of this study was to evaluate the performance of a one-dimensional reservoir selective withdrawal model (SELECT) as a tool for supporting downstream water quality management for Daecheong and Imha reservoirs. The simulated water quality variables including water temperature, dissolved oxygen (DO), conductivity, turbidity were compared with the field data measured in tailwater. The model showed fairly satisfactory results and high reliability in simulating observations. The coefficients of determinant between simulated and observed turbidity values were 0.93 and 0.95 for Daecheong and Imha reservoirs, respectively. The outflow water quality was significantly influenced by water intake level under fully stratified condition, while the effect of intake amount was minor. In conclusion, the SELECT is simple but effective tool for supporting downstream water quality prediction and management for both reservoirs.

• Journal of Korean Society on Water Environment
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• v.23 no.2
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• pp.228-235
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• 2007

For efficient turbid water withdrawal in the Imha reservoir, a selective withdrawal facility was recently installed and operated during summer season of year 2006. In this research, CE-QUAL-W2 model was utilized to assess the efficiency of the selective withdrawal facility, in comparison with the original surface withdrawal, on turbid water management. Model calibration was carried out using data observed at four automatic monitoring stations in the reservoir. It was found that the model appropriately simulated, with the RMSE less than 5.2 NTU, the observed vertical and horizontal distributions of water temperature and turbidity as well as the location of maximum turbid water at each monitoring station. The analysis results showed that selective withdrawal is more effective in removing high turbid water than surface withdrawal as selective withdrawal contributed to reducing $35Mm^3$ of high turbidity water (> 100 NTU) in the reservoir by increasing outflows of high turbid water. Therefore, effective management of turbid water in the reservoir can be achieved by changing locations of intake depending on turbid water distribution conditions. The results of this study will provide some basic information for establishing better operation strategies to cope with turbid water problems.

• Journal of Korean Society on Water Environment
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• v.27 no.6
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• pp.743-753
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• 2011

One of the most important water management issues of Soyang Reservoir, located in North Han River in Korea, is a long term discharge of turbid water to downstream during flood season. Installation of a selective withdrawal structure (SWS) is planned by the reservoir management institute as a control measure of outflow water quality and associated negative impacts on downstream water use and ecosystem. The objective of the study was to explore the effectiveness of the SWS on the control of outflow turbidity under two different hydrological years; one for normal flood year and another for extreme flood year. A two-dimensional (2D), laterally averaged hydrodynamic and water quality model (CE-QUAL-W2) was set up and calibrated for the reservoir and used to evaluate the performance of the proposed SWS. The results revealed that the SWS can be an effective method when the ${\Theta}$ value, the ratio between the amount of turbid water that containing suspended sediment (SS) greater than 25 mg/L and the total storage of the reservoir, is 0.59 during the normal flood year. However, the effectiveness of the SWS could be marginal or negative in the extreme flood year when ${\Theta}$ was 0.83. The results imply that the SWS is an effective alternative for the control of turbid water for moderate flood events, but not a sufficient measure for large flood events that are expected to happen more often in the future because of climate change.

• Journal of Korean Society of Forest Science
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• v.108 no.3
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• pp.329-340
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• 2019

Water pollution in erosion control dams is a major issue for forest watershed management, but the effects of erosion control dams on water quality remain poorly understood. In this study, water quality data from streams and dam reservoirs were collected over the Nakdong river basin. Monitored data were further analyzed to examine the relationship between watershed characteristics and water quality. Of the total 43 erosion control dams, less than 10% had lower water quality that was not suitable for agricultural use. TOC and oxygen demand, SS and turbidity, SS and Chl-a, and Chl-a and turbidity showed high correlations (p < 0.01) both in stream water and in detained water. BOD and SS, BOD and Chl-a, BOD and turbidity, and TOC and Chl-a showed high correlations only in stream water. Overall, the results demonstrated that for most erosion control dams the water quality was relatively good. In addition, the quality of downstream water is somewhat affected by the water detained by erosion control dams, in limited ways.

• Journal of Environmental Impact Assessment
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• v.20 no.4
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• pp.575-583
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• 2011

In this study, the plausible grid size was estimated to increase for efficiency of reservoir management using 3 dimensional water quality model. To validate utilization of a real time water quality management tool, ELCOM-CAEDYM model was applied to Soyang reservoir in korea. 100m grid size can represent the real topography and take out exact analysis results. $400{\times}400m$ grid can be easily used to analysis because of data capacity. Consequently, the grid size of 200m or 300m was recommended to establish 3D model considering the required simulation time and the irrelevance between horizontal grid size and vertical distribution for temperature and turbidity analysis.

• Journal of Sensor Science and Technology
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• v.24 no.5
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• pp.331-341
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• 2015

In this paper, real-time water quality monitoring system of small water supply facilities based on IEEE 802.15.4e-2012 DSME MAC and IEEE 802.15.4g-2012 PHY standard is presented, which is capable to acquire for highly reliable water quality information in the wide outdoor areas for effective water quality management of small water quality facilities is distributed in the long distance and remote areas. Previously, Long distance transmission is difficult in most water quality sensor module is using RS-485 protocol. But with this system, even in harsh outdoor environment, it is possible to establish a radio wave sensor in a wide area network, and not only water quality sensor shall be connected to the wireless system, but also wireless integrated management system shall provide more effective way of management of the numerous small water supply facilities spread throughout the community, so that the administrator can remotely monitor the data of water turbidity, pH, residual chlorine in the water-supply, water-level, and generate alarm to cope with risks. The management of small water facilities is done by residents will be very effective to notice water quality information of small water facilities to residents.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.285-291
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• 2009

Water is a strategic resource for Singapore due to its small land mass and more than half of the mainland serves as catchment for raw water, including construction sites. Construction site typically involves earthworks and in conjunction with the frequent and intense rainstorm in Singapore, produce runoff of high turbidity due to suspended sediments. The resulting high concentration of suspended sediment in construction site runoff very often leads to aesthetically unpleasant reservoirs and potentially increases the treatment cost of raw water. To mitigate this, the local standard requires the discharged concentration of total suspended solids of construction runoff leaving a construction site to be less than 50mg/l which is a very high standard. This paper will present, examine and discuss particular issues and practices of Singapore's construction industry in meeting this requirement. The focus will be on two areas: Government lead initiatives and industry practices. How the government agencies worked together with the industry professionals to develop a system to ensure meeting of the standard is discussed. In addition, the types of industry practices, including various Best Management Practice to reduce erosion in construction sites and implement effective sedimentation on construction sites are examined.

• Journal of the Korean Wood Science and Technology
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• v.48 no.4
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• pp.472-487
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• 2020

With the emergence of abnormal climate due to the rapid industrialization, the importance of water quality management and management costs are increasing every year. In Korea, for the management of total phosphorus and total nitrogen, the major materials causing the water quality pollution, coagulants are injected in sewage treatment plants to process organic compounds. However, if the coagulant is injected in an excessive amount to PAC (Poly Aluminium Chloride), a secondary pollution problem might occur. As such, a study on the applicability of natural material-based coagulant is being conducted in Korea. Thus, this study aimed to evaluate the applicability of a mixed coagulant developed by analyzing water quality pollutants T-P, T-N as well as their turbidity, in order to derive the optimum mixing ratio between PAC and torrefied wood flour for the primary settling pond effluent. Under the condition where the content of PAC (10%) and torrefied wood flour is 1%, T-P showed the maximum removal efficiency of 92%, and T-N showed approximately 22%. This indicates that removal of T-N which includes numerous positively charged organic compounds that are equivalent to mixed coagulant is not well accomplished. Turbidity showed the removal efficiency of approximately 91%. As such, 1% of torrefied wood flour was determined to be the optimum addition. As a result of analyzing the removal efficiency for organic compounds by reducing PAC concentration to 7%, T-P showed a high maximum removal efficiency of 91%, T-N showed 32%, and turbidity showed the maximum of 90%. In addition, a coagulation process is performed by using the mixed coagulant based on 1% content of torrefied wood flour produced in this study by performing a coagulation performance comparative experiment with PAC (10%). As a result, PAC concentration was reduced to 30-50%, a similar performance with other coagulants in market was secured, PAC injection amount was reduced that an economic effect can be achieved, and it is considered to perform a stable water treatment that reduces the secondary pollution problem.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.6
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• pp.699-705
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• 2007

In this study, the improvement of the operation condition and the water quality in water treatment plant by operating information system(OIS) was evaluated for Ansan water treatment plant. The average flow rate of raw water in the year 2005(after constructing the OIS) appeared 15.6 % lower than that in the year 2004(before constructing the OIS). The mean value(12.37 NTU) of raw water turbidity in the year 2005 remained constant, or nearly so with that(12.06 NTU) in the year 2004. The average dosing rates of coagulant appeared 12.06 mg/L in the year 2005 which was higher than 10.31 mg/L in the year 2004. Furthermore, the average turbidity concentration of fresh water in the year 2005 appcared slightly better than that in the year 2004. From $COD_{Mn}$ and BOD concentration of raw water, the water quality in the year 2005 were better than those in the year 2004. The average concentration of $KMnO_4$ in the year 2004 and the year 2005 was 2.95 mg/L and 1.25 mg/L, respectively, and the average concentration of THMs in the year 2004 and the year 2005 appeared 0.038 mg/L and 0.025 mg/L, respectively. Therefore, the fresh water quality in the year 2005 was better than that in the year 2004. In this study, it is considered that the operation of Ansan water treatment plant may be optimized by OIS, and thus the OIS may be very useful method to improve the water quality.

• Journal of Korean Society on Water Environment
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• v.35 no.6
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• pp.470-480
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• 2019

The Doam lake watershed was designated as a non-point pollution management area in 2007 to improve water quality based on watershed management implementation. There have been studies of non-point source reduction with respect to the watershed management impacting the pollutant transport of the reservoir. However, a little attention has been focused on the impact of water quality improvement by the management of the dam operation or the guidelines on the dam operation. In this study, the impact of in-lake management practices combined with watershed management is analyzed, and the appropriate guidelines on the operation of the dam are suggested. The integrated modeling system by coupling with the watershed model (HSPF) and reservoir water quality model (CE-QUAL-W2) was applied for analyzing the impact of water quality management practices. A scenario implemented with sedimentation basin and suspended matter barrier showed decrease in SS concentration up to 4.6%. The SS concentration increased in the scenarios adjusting withdrawal location from EL.673 m to the upper direction(EL.683 m and EL.688 m). The water quality was comparably high when the scenario implemented all in-lake practices with water intake at EL.673 m. However, there was improvement in water quality when the height of the water intake was moved to EL.688 m during the summer by preventing sediments inflow after the rainfall. Therefore, to manage water quality of the Doam lake, it is essential to control the water quality by modulating the height of water intake through consistent turbidity monitoring during rainfall.