• Journal of Wetlands Research
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• v.20 no.1
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• pp.43-53
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• 2018

Laguna Lake is the largest inland fresh water body in the Philippines. It primarily serves as a site for aquaculture, hydropower, transportation, and water supply industries. Due to Laguna Lake's diverse functionalities, competition among water users became prominent. Water quality began to deteriorate due to various pollutant contributions in this process, thereby affecting the soundness of the aquatic ecosystem. This study was conducted to evaluate the current water quality management policy from the viewpoint of ecological environment through the evaluation of the water quality of Laguna Lake. Concentrations of water pollutants such as ammonia ($NH_3$), biochemical oxygen demand (BOD), chloride ($Cl^-$), pH, and total suspended solids (TSS) exceeded the water quality standards of the Philippines' Department of Environment and Natural Resources (DENR). The water quality of the lake was also affected by the pollutant load due to agriculture and urban stormwater runoff in the watershed. The salinity and contaminated water from Pasig River also affected the water quality of Laguna Lake. Long-term water quality analysis showed that the water quality of Laguna Lake is also influenced by rainfall-related seasonal variations. The results of the water quality analysis of Laguna Lake indicated that the environmental management techniques of the Philippines should be changed from the conventional water management into an integrated watershed management scheme in the future. It is therefore necessary to study and introduce advanced watershed management measures in the Philippines based from the policies of other developed countries.

• Journal of Korean Society on Water Environment
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• v.27 no.1
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• pp.88-97
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• 2011

To identify the inflow and outflow characteristics of allchthonous organic matters and examine the change of allochthonous organic matter load pattern due to the climate change, we investigated the temporal variations of DOC and POC concentrations within inflow water and dam discharge water and spatio-temporal distribution of POM within the lake water in Lake Soyang which is the largest dam reservoir in Korea in 2006. Most of allochthonous DOC flowed into the lake water during initial rain and was not affected by the amount of precipitation, whereas most of allochthonous POC flowed into during concentrated heavy rain and the concentration of POC was significantly associated with the amount of inflow water and precipitation. Calculated annual allochthonous organic matter loads in Lake Soyang from 2003 to 2006 using the regression equation between the amount of inflow water and the concentration of POC indicate allochthonous organic matter loads are mainly affected by total influx and extreme influx of inflow water. The spatio-temporal distribution of POM indicated allochthonous organic matter of inflow river during flood period in July transported from upper part to middle and lower part of the lake a month later respectively along the middle layer of water column in Lake Soyang.

• Magazine of the Korean Society of Agricultural Engineers
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• v.45 no.7
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• pp.38-48
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• 2003

Lake water quality assessment information is useful to anyone involved in lake management, from lake owners to lake associations. It provides lake water quality criteria, which can improve the ways how to manage out lake resources and how to measure current conditions. It also provides a knowledge base so that the lakes can be protected and restored. Here, the Freshwater Lake Water Quality Management System(FLAQUM) was developed. The results of FLAQUM application by scenario proved that pollutant load at rainfall by the nonpoint sources was much more than normal times at rainfall. From the result of Scenario I (pollutant source increase case), the concentrations of Boryeong freshwater lake were BOD 9.43mg/L, T-N 4.53 mg/L and T-P 0.21 mg/L, respectively, and those values exceed the standard of agricultural water. And in case of Scenario I and II(the present case) excluding Scenario III (pollutant source decrease case), all of T-N and T-P are either mesotrophication or eutrophication, on the other hand when 60% of pollution source is removed, the concentrations of Scenario III were BOD 3.21 mg/L, T-N 0.95 mg/L, T-P 0.11 mg/L, respectively, and which satisfies the standard of agricultural water quality.

• 한국해양학회지
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• v.6 no.2
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• pp.63-77
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• 1971

An year-long survey of chemical water quality for Lake Eui-am in Kang-won Province, Korea, was conducted from June 1970 to May 1971 to study the water quality and seasonal variations of productivities in relation to selected physical and chemical environmental factors. A monthly series of water samples were taken at the deepest basin of 18m depth of the lake. Water quality parameters determined were water temperature, Secchi disc reading(transparency), pH, O$\_$2/, CO$\_$2/, alkalinity, acidity, Cl, hardness, Ca, Mg, total residue, total ignitious residue, COD, BOD$\_$5/, nutrients, total-Fe, soluble Fe, Mn and Cu. On the whole, the results indicate that the chemical water quality of Lake Eui-am is high, and vary with season. The lake water is characterized that higher levels of dissolved oxygen(8.6 ml/L in mean of whole water) or percent saturation of dissolved oxygen(114%), and of nitrate nitrogen (523 $\mu\textrm{g}$/L). On the other hand, CO$\_$2/(9.6ppm), chlorides(3.5ppm), Ca(7.7ppm) Mg(2.2ppm), hardness(28.5ppm), silica(2.4ppm) and BOD$\_$5/(1.08ppm) are quite low. In terms of nutrient levels, the lake water exhibit slight signs of eutrophication. The high values for nitrate nitrogen, soluble iron and Cu of the lake water suggest that there are some imputs such as domestic and industrial discharges to the lake.

• Journal of Environmental Impact Assessment
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• v.3 no.2
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• pp.33-45
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• 1994

Water quality of Chongju and Daejeon Water Intake Tower Region, embayments in Daechong Reservoir was found to be worse than that of main lake after analysis of water which were sampled during April, July, October in 1993. Concentration of COD and SS at those two water intake tower sites were 2.8-5.6 mg/l and 2.2-3.2 mg/l, higher than that of main lake. T-N concentration of those two sites was 1.1-1.9 mg/l similar to that of main lake, and T-P concentration of those two sites was 0.14-0.18 mg/l, higher than that of main lake. This study used water quality model of embayment which can analyse pollutant loads from stream and surrounding land use, advection, decay, and diffusion transport between embayment and main lake. The model can predict water quality of embayment according to the change of pollutant load, water elevation of embayment, quantity of water intake in order to suggest water quality management. This study suggests embayment water quality management alternatives, 1) construction of waste water treatment facilities at embayment and main lake for the decrease of pollutant loading, 2) water intake at main lake less polluted or eutrophicated than embayment, and 3) outflow elevation selection for polluted hypolimnion water outflow during stratification.

• Magazine of the Korean Society of Agricultural Engineers
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• v.44 no.6
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• pp.124-136
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• 2002

A freshwater lake water quality management system(FLAQUM) was developed to help regional manager for the water quality of a rural basin. The integrated user interface system FLAQUM written in Visual Basic, includes three subsystems such as a database management system, basin pollutant loads simulation model using SWMM model and freshwater lake water quality simulation model using WASP5 model. Pollutant load simulation model was applied to simulate the discharge and pollutant loading from the watershed, and freshwater lake water quality model was applied to analyze the changes in water quality with respect to watershed pollutant loads, and this model could be used in planning to control watershed pollutant source for water quality management. Database management system was constructed fur all input and output data processing, and it can be used to analyze statistical characteristics using constructed data. Results are displayed both graph and text for convenience of user. The results of FLAQUM application to Boryeong freshwater lake showed that the lake was in eutrophic condition. The major contribution of pollution comes from tributary No.1 and No.4, which have a large number of livestock farms. Therefore, water quality management must be focused on appropriate management of the livestock farming in the two breanchs.

• Journal of Korean Society on Water Environment
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• v.25 no.5
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• pp.742-749
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• 2009

To examine the characteristics of the nutrient release from the sediments in two reservoirs, Lake Paldang and Lake Cheungpyeung, we analyzed physical and chemical properties of the sediments and calculated the nutrient release rates from the sediments. The particle properties of sediments in Lake Paldang changed from silt to sand after summer rainy season, especially in the water area of the Kyeungan River where the water depth was shallow and the width of river was narrow. The sediments in Lake Cheungpyeung had higher contents of silt and clay than in Lake Paldang, and the particle size was not much different before and after rainfall. The release rates of nutrients in two lakes varied with the kind of nutrients and the season. The release rates of DTN and ${NH_4}^+-N$ in Lake Paldang were faster in spring than autumn. But the Lake Cheungpyeung showed similar values of release rates before and after summer rainy season. ${NO_3}^--N$ and phosphorous were not released from sediments or were absorbed into sediments all the time in two lakes. Compared with other lakes, the sediments of two lakes consisted of bigger particles and had a lower organic matters content than other lake-type reservoirs. Due to the short hydraulic retention time and no stratification throughout the year in Lake Paldang and Lake Cheungpyeung, the release rates of nutrients from sediment in these reservoirs were lower than other lakes and this seems to be a typical characteristic of river-type reservoirs.

• Journal of Environmental Science International
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• v.31 no.5
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• pp.431-445
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• 2022

The Gwangju Stream is a major tributary of the Yeongsan River. To maintain environmental and ecological functions in the stream, the flow is secured by natural water from the Mudeung Mountain as well as waters discharged from Lake Juam and the Gwangju sewage treatment plants. A substantial amount of water is supplied into the upper reaches of Gwangju Stream from Lake Juam. To examine the ecological effects of the water input from Lake Juam on the Gwangju Stream, a field survey of phytoplankton community species and an evaluation of water properties was conducted at five stations, from station GJ1 before the inflow to station GJ5 in the lower region. Nutrient levels decreased in the vicinity of the Lake Juam inflow, suggesting that this water inflow can contribute to the reduction of eutrophication in the stream. The phytoplankton community was mainly composed of Bacillariophyceae, Chlorophyceae, and Cyanophyceae, and the community structure was similar to that of the other study sites located near the water inflow regions. The inflow of water from Lake Juam can affect water quality and the phytoplankton community over a limited area, reducing eutrophication and increasing water flow in the Gwangju Stream.

• Journal of Korean Society on Water Environment
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• v.31 no.4
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• pp.367-376
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• 2015

The momentum and kinetic turbulent energy carried by the wind to a stratified lake lead to basin-scale motions, which provide a major driving force for vertical and horizontal mixing. A three-dimensional (3D) hydrodynamic model was applied to Lake Tahoe, located between California and Nevada, USA, to simulate the dominant basin-scale internal waves in the deep lake. The results demonstrated that the model well represents the temporal and vertical variations of water temperature that allows the internal waves to be energized correctly at the basin scale. Both the model and thermistor chain (TC) data identified the presence of Kelvin modes and Poincare mode internal waves. The lake was weakly stratified during the study period, and produced large amplitude (up to 60 m) of internal oscillations after several wind events and partial upwelling near the southwestern lake. The partial upwelling and followed coastal jets could be an important feature of basin-scale internal waves because they can cause re-suspension and horizontal transport of fine particles from nearshore to offshore. The internal wave dynamics can be also associated with the distributions of water quality variables such as dissolved oxygen and nutrients in the lake. Thus, the basin-scale internal waves and horizontal circulation processes need to be accurately modeled for the correct simulation of the dissolved and particulate contaminants, and biogeochemical processes in the lake.

• Journal of Korean Society on Water Environment
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• v.35 no.4
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• pp.352-361
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• 2019

The purpose of this study is to analyze the characteristics and correlations of the Yeongcheon Lake in order to reduce the occurrence of harmful cyanobacteria. In this study, we investigated the water quality and phytoplankton of the lake from May to November in 2017. Correlation and data mining analyses were performed to analyze the relationship between the two factors. The water temperature was lowest at the point where the Yeongcheon Lake inflow occurs at Imha Lake. It was highest at the point where the outflow occurs to Angye Lake. The pH was also highest at the outflow point, but in the case of DO, it was highest at the midpoint between the inflow and outflow. The main cyanobacteria that emerged during the study period were Oscillatorialimosa, Microcysti saeruginosa and Aphanizomenon flos-aquae. As a result of correlation analysis, the water temperature, inflow, COD loading, TOC loading at the inflow point of the Yeongcheon Lake were the items that were related to the harmful cyanobacteria. The data mining analysis indicated that the TP loading and harmful cyanobacteria in the inflow point of the Yeongcheon Lake were influential on the detrimental cyanobacteria in the Yeongcheon Lake outflow point. When the TP loading was less than 39.0 kg/day at the inflow site, it was expected that the amount of harmful cyanobacteria could be maintained below 10,000 cells/mL.