• Journal of Korean Society on Water Environment
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• v.29 no.6
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• pp.762-776
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• 2013

Load duration curve was applied to determine important water quality parameter control term for improvement of Paldang lake water quality. Load duration curve was analyzed with long term data from 1985 to 2012 including water quality, flow rate and climate state of Paldang water environment. From the result of flow rate patterns of paldang lake, differences between high and low flow rate of each year showed tendency of increase because rainfall characteristics of paldang lake watershed were changed by climate exchange. Both of land use state of upper Paldang lake watershed and number of limit excess from load duration curve indicated that seasonal action related with land use such as agricultural fertilizer distribution in upper watershed affected Paldang lake water quality. So focused BOD (biological oxygen demand) management during spring season from march to June is required to control organic materials in Paldand lake. The main affecting factor of TOC (total organic carbon) increase in Paldang lake was initial rainfall after march. T-N (total nitrogen) kept increasing during research period, so enhancement of T-N standard is needed to T-N control. Initial rainfall and increase of temperature during spring season from March to June showed a positive correlation with TP (total phosphorus) and Chl-a, respectively.

• Journal of Korean Society on Water Environment
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• v.25 no.2
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• pp.295-305
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• 2009

The purpose of this study was to understand of water quality characteristics of lake Paldang, especially at a certain representative site, right in front of Paldang dam ($P_2$ site) and to propose the directions of water quality management of lake Paldang. Water characteristics at $P_2$ site was investigated by principle components analysis and the Pearson correlation coefficient analysis. Also, seasonality was identified by the Kruskal-Wallis test and long term trend of nutrients and chlorophyll-a was analyzed by seasonal decomposition method at lake Paldang statistically. The primary factor affecting on water quality at $P_2$ site was identified as nutrients, while physical parameters, such as rainfall and inflow rate were also important factors. At the result of linear regression analysis particulate organic phosphorus (POP) vs total phosphorus (TP) showed very high correlation of 0.78. TP loading was increased annually from 1995 to 2006. Chlorophyll-a and nutrients show seasonality at $P_2$ site. Long term trend of Chlorophyll-a was increased by increase of TP at lake Paldang.

• Journal of The Korean Society of Agricultural Engineers
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• v.51 no.6
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• pp.53-62
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• 2009

The EFDC (Environmental Fluid Dynamics Code), a numerical model for simulating three-dimensional (3D) flow, transport, and biogeochemical processes in surface water systems including rivers, reservoirs, and estuaries, was applied to assess the effect of sea water and fresh water exchange rates ($Q_e$) on the mixing characteristics of a conservative pollutant (tracer) induced from upstreams and salinity in Saemangeum Lake, Korea. The lake has been closed by a 33 km estuary embankment since last April of 2006, and now seawater enters the lake partially through two sluice gates (Sinsi and Garyuk), which is driving the changes of hydrodynamic and water quality properties of the lake. The EFDC was constructed and calibrated with surveyed bathymetry data and field data including water level, temperature, and salinity in 2008. The model showed good agreement with the field data and adequately replicated the spatial and temporal variations of the variables. The validated model was applied to simulated the tracer and salinity with two different gate operation scenarios: RUN-1 and RUN-2. RUN-1 is the case of real operation condition ($Q_e=25,000,000\;m^3$) of 2008, while RUN-2 assumed full open of Sinsi gate to increase $Q_e$ by $120,000,000\;m^3$. Statistical analysis of the simulation results indicate that mixing characteristics of pollutants from upstream can be significantly affected by the amount of $Q_e$.

• Journal of Korean Society on Water Environment
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• v.21 no.6
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• pp.584-594
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• 2005

The spatio-temporal abundance pattern of algae in Lake Paldang from 2002 to 2004 was investigated. The concentration of chlorophyll a representing algal biomass had fluctuated intensively throughout the year. Among three years, the highest algal biomass was shown in 2002, and typical growth peak of concentration of chlorophyll a was occurred in spring and autumn. There had been frequent rainfall in spring drought period in 2003 and it resulted in the decrease of the algal biomass. The distribution pattern of four algal groups on the surface water of Lake Paldang showed different abundance by season and by water area. In particular, different algal growth characteristics by water areas were observed. Influences of various environmental parameters on algal abundance in four water areas of Lake Paldang were analyzed statistically. From the results of Peason correlation analysis, it was understood that the kinds and affects of environmental parameters were different according to water areas and seasons. Based on the factors analysis of environmental parameters on the concentration of chlorophyll a, stepwise regression models whose independent variables were the factors produced by factor analysis and dependent variable was the concentration of chlorophyll a were derived by water areas and seasons. As a whole, factors related with organics and photosynthesis were revealed to have high affects to algal abundance, whereas limiting nutrients such as phosphorus and nitrogen showed little affect in Lake Paldang.

• Korean Journal of Environmental Agriculture
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• v.39 no.3
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• pp.197-203
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• 2020

BACKGROUND: Most lakes have increased concerns about water pollution due to the inflow of non-point sources caused by human activities. Therefore, the lake water quality survey was conducted in order to propose effective plans for water quality management by analyzing the characteristics of lakes and the change of water quality. METHODS AND RESULTS: In order to investigate the physicochemical water quality in Daedong lake, water quality analysis was undertaken from July 2018 to June 2019. Water temperature was ranged from 7.8 to 34.3℃ and pH varied from 6.9 to 10.2. The concentration of Dissolved oxygen, Suspended solid, Biochemical Oxygen Demand (BOD), and Chemical Oxygen Demand (COD) were 5.6 ~ 17.2 mg/L, 2.4 ~ 35.3 mg/L, and 4.5 ~ 15.1 mg/L, and 0.9 ~ 2.8 mg/L, respectively. The Total Nitrogen (T-N) concentration ranged from 0.974 ~ 2.126 mg/L, and Total Phosphorus (T-P) concentration ranged from 0.014 ~ 0.057 mg/L. The Chlorophyll-a (Chl-a) ranged from 2.7 ~ 37.9 mg/㎥. Through Carlson TSIm assessment using T-P and Chl-a results, evaluating trophic state, Daedong lake was evaluated as mesotrophic. CONCLUSION: Water pollution management plan needs such as nutrient removal technology and nonpoint source management for prevention of eutrophication in Daedong lake.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.4
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• pp.297-306
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• 2023

Saemangeum Lake is the largest artificial lake in Korea. The continuous deterioration of lake water quality necessitates the introduction of novel water quality management strategies. Therefore, this study aims to identify the spatiotemporal water quality characteristics of Saemangeum Lake using data from the National Water Quality Measurement Network and provide basic information for water quality management. In the water quality parameters of Saemangeum Lake, water temperature and total phosphorous content were correlated, and salt, total nitrogen content, pH, and chemical oxygen demand were significantly correlated. Other parameters showed a low correlation. The spatial principal component analysis of Saemangeum Lake showed the characteristics of its four zones. The mid-to-downstream section of the river affected by freshwater inflow showed a high nutrient salt concentration, and the deep-water section of the drainage gate and the lake affected by seawater showed a high salt concentration. Two types of water qualities were observed in the intermediate water area where river water and outer sea water were mixed: waters with relatively low salt and high chemical oxygen demand, and waters with relatively low salt and high pH concentration. In the principal component analysis by time, the water quality was divided into four groups based on the observation month. Group I occurred during May and June in late spring and early summer, Group II was in early spring (March-April) and late autumn (November-December), Group III was in winter (January-February), and Group IV was in summer (July-October) during high temperatures. The water quality characteristics of Saemangeum Lake were found to be affected by the inflow of the upper Mangyeong and Dongjin rivers, and the seawater through the Garuk and Shinshi gates installed in the Saemangeum Embankment. In order to achieve the target water quality of Saemangeum Lake, it is necessary to establish water quality management measures for Saemangeum Lake along with pollution source management measures in the upper basin.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2003.10a
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• pp.631-634
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• 2003

A subwatershed within the Lake Juam was monitored to identify hydrologic and water quality characteristics. Rainfall record was collected and flow rate measurement and water quality sampling were conducted periodically at the watershed outlet. Water quality of storm period was worse than that of base flow period. Nutrient loading from the watershed was governed by only a few storms during study period. Nonpoint source pollution was identified major problem for water quality management in Juam Lake.

• Korean Journal of Environment and Ecology
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• v.26 no.3
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• pp.374-381
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• 2012

In this study, ecological characteristics of Zacco platypus population in Lake Hoengseong region, including the up-and downstream in Lake, were investigated from April to November, 2010. The results compared with regional dynamics of Z. platypus population showed a dominant population among the other fish population, and also upstream has relatively high as 1,707 (78.70%) individuals than those of other sites. The regression coefficient (b) in relation to length-weight on Z. platypus population were 3.28 which appeared relatively a stabilized habitat condition in Lake Hoengseong region and 3.28 at the upstream and 3.10 in Lake Hoengseong and 3.09 at the downstream. Condition factor on Z. platypus population in Lake Hoengseong region showed stabilized population as 0.003 value, and especially the condition factors at the upstream were relatively higher than those at the downstream and Lake Hoengseong, indicate that Z. platypus population at the upstream displayed to be maintained as the most good condition in relation to trophic states. As a results of compared with body size on Z. platypus population, was investgated as highly distribute between 30~50mm and 70~90mm at upstream; 60~80mm in Lake Heongseong; 70~100mm at downstream, respectively. As a results, Z. platypus population at the upstream among Lake Hoengseong region displayed the most stabilized growth condition, and Z. platypus population were inhabitable in lotic and lentic environments based on good habitat condition.

• Korean Journal of Ecology and Environment
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• v.46 no.1
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• pp.128-134
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• 2013

In the summer season (June~August) during the study period of Lake Doam, average concentrations of major water quality parameters, COD, SS, TN, and TP were 4.0, 16.2, 3.129 and $0.077mg\;L^{-1}$, respectively, and Chl-a was $11.8mg\;m^{-3}$. The result has indicated that Lake Doam was a meso-eutrotrophic lake. Lake Doam data from the summer season (June~August), precipitation from 2001 to 2012, and water quality (COD, SS, TN, TP, Chl-a etc.) of seven years (2001, 2002, 2004 and 2009~2012), were statistically analyzed for long-term trends by Mann-Kendall test and Sen's slope estimator methods. The statistical results showed that precipitation, SD, COD, TN, $NO_3-N$, $NH_3-N$ and Chl-a had decreasing trends, and EC, turbidity, SS, TP and DIP had increasing trends. Suspended solids and total phosphorus were directly affected by precipitation. In the case of suspended solids, more aggressive and constructive plans need to be implemented than the current turbidity reduction project to achieve the targeted water quality ($5mg\;L^{-1}$ of SS) in Lake Doam. In particular, we need to specify a project that considers the steep topographic characteristics of high, land farming areas and precipitation conditions of the Lake Doam watershed, which can increase the efficiency of a turbidity reduction project.

• Journal of Industrial Technology
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• v.25 no.B
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• pp.11-18
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• 2005

When it is raining or snowing, floating debris flows into a lake and raises its turbidity. High level of turbidity in the lake often causes eutrophication, which pollutes the water. In order to collect and present some essential information for effective management plan for water quality, we carried out our research at the watershed of Mandae-cheon located at the upstream of Soyang Lake. We examined water quality at the time of rainfall or snowfall to analyze the changes in the amount of suspend soils(SS) in the lake.