• KCID journal
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• v.8 no.2
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• pp.64-72
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• 2001

Sihwa dyke was constructed during the period from June, 1987 to January, 1994 and the sluice gates were opened to allow sea water intrusion and outflow to improve water quality of the lake since June, 1997. Bottom sediment samples from 29 stations were co

• Journal of the Korean Institute of Landscape Architecture
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• v.28 no.6
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• pp.114-126
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• 2001

The purpose of this study is to establish the databases of pollutant sources and water quality measurement data by utilizing GIS, and making the user interface for the management of pollutant sources. Yeongsan Estuarine Lake was formed of a huge levee of 4.35 km constructed by an agricultural reclamation project. Water quality of the reservoir has been degraded gradually, which mainly attributes to increase of point and non-point source pollutant loads from the lake's watershed of 33,374.3 $\textrm{km}^2$ into it. Application of GIS to establishment of the database was researched of pint source such as domestic sewage, industrial wastewater, farm wastes, and fishery wastes, and non-pont source such as residence, rice and upland field, and forest runoffs of the watershed of the lake. NT Acr/Info and ArcView were mainly utilized for the database formation. Land use of the watershed using LANDSAT image data was analyzed for non-point source pollutant load estimation. Pollutant loads from the watershed into the reservoir were calculated using the GIS database and BOD, TN, TP load units of point and non-point sources. Total BOD, TN, TP loads into it reached approximately to 141, 715, 2,094 and 4,743 kg/day respectively. The loads can be used as input parameters for water quality predicting model of it. A user-friendly interface program was developed using Dialog Designer and Avenue Script of AcrView, which can perform spatial analysis of point and non-point sources, calculate pollutant inputs from the sources, update attribute data of them, delete and add point sources, identify locations and volumes of water treatment facilities, and examine water quality data of water sampling points.

• Journal of Korean Society on Water Environment
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• v.24 no.2
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• pp.239-246
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• 2008

In this study, an optimized deterministic water-quality model was constructed to estimate water quality of a river and lake in the upstream basin of a dam. A stochastic water-quality analysis using reliability analysis technique was applied to the model. The model was tested in the 13.9 km reach from Maeil stage station of Kyechun to Hoengsung Dam of Sum River. After finding hydraulic characteristics from nonuniform flow analysis, Broyden-Fletcher-Goldfarb-Shanno (BFGS) optimization technique for model calibration was applied to determine optimum reaction parameters, and model verification was performed based on these. The stochastic model, using Mean First­Order Second­-Moment (MFOSM) and Monte-Carlo methods, was applied to the same reach as the deterministic study. Variations of discharge and water quality in headwater were considered, as well as variations of hydraulic coefficients and reaction coefficients. The statistical results of output variables from MFOSM were similar to those from the Monte-Carlo method. Risk analysis using MFOSM and Monte-Carlo methods presented the probabilities of some locations in the Hoengsung Lake violating existing water-quality standards in terms of DO and BOD.

• Journal of Environmental Science International
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• v.5 no.6
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• pp.763-770
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• 1996

This study was performed to analyze the variation characteristics of writer qulity, correlation analysis of water quality data at each site and among the items of water Quality data. Water quality for analysis was monthly values of water temperature, pH, dissolved oxygen, biochemical oxygen demand, chemical oxygen demand, suspended solid, 7-N and T-P checked in Daecheong Lake from January to December, 1995. It was analyzed variation of monthly water qulity was well from February to April, water temperature and COD seemed to have high correlationships at all sites. Regression equation is COD = 0.07 Water temperature +1.23 ($R^2$: 0.7616) . Results of the correlation analysis of water quality data showed that DO had high correlationships between site 1 and site 2, BOD did site 1 and 3, COD did site 1 and 2, 55 did site 5 and 6, 7-N did 2 and 3, 7-P did site 4 and 6. Regression equations for estimate of water quality data are as follows. $DO_1$=4.46+0.59 DO, ($R^2$=0.8868), $BOD_1$ = 0, 52+0.63 BOD3 ($R^2$ = 0.6390) $COD_2$ = 0.44+0.71 $COD_1$ ($R^2$ = 0.9183), SS6 = 0.89+0.7055.($R^2$ = 0.9155) $TN_3$ = 0.151 +0.886 $TN_2$ ($R^2$ = 0.9415), $TP_4$ = 0.004+5.758 $TP_6$ ($R^2$ = 0.9669)

• Journal of Wetlands Research
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• v.22 no.1
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• pp.49-58
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• 2020

The excessive use of fertilizer and compost in agricultural land increases the accumulation of nutrients in soil. The surplus nutrients in soil transported through surface and sub-surface flow can lead to water pollution problems and algal bloom. Moreover, nutrient accumulation and continuous crop cultivation changes the physical structure of the soil, which increases the potential of nutrient. The cultivation in the Daecheong Lake reservoir area may have a direct effect on the lake's water quality due to leaching and releasing of nutrients when water level rises. This research was carried out to analyze the physical and chemical properties of soil in the agricultural areas surrounding Daecheong Dam reservoir to provide basic data available for the establishment of Daecheong Lake water quality management measures. The soil of the Daecheong Lake reservoir was classified as sandy Loam, where surplus nutrients can be transported. Chemical compositions in the soil were found to be significantly affected by use of different fertilizer amounts. Nutrient outflow occurred during spring rainfall events from the rice paddy fields, whereas excess nutrients from summer to fall seasons originated from dry paddy fields. Nutrient outflow from dry paddy fields is mainly from sub-surface flow. Organic agricultural wastes from agricultural land and excessive vegetation inside the river was also evaluated to contribute to the increase in organic matter and nutrients of the river. The results can be used to select the priority management area designation and management techniques in the Daecheong Lake for water quality improvement.

• Journal of Korean Society on Water Environment
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• v.25 no.6
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• pp.855-862
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• 2009

This paper pointed out major problems of land use regulation policy surrounding Paldang Lake as follows: (1) inefficient management system, (2) inconsistent administrative management, (3) illogical selection of regulated area, (4) contradictory present system, and (5) controversial discharge control. Several regulation laws for the land-use surrounding Paldang Lake caused confusion of application and inefficiency of management. Amendment of regulation laws made it possible that the regulated area was developed, which resulted in the deterioration of water quality. In addition, successive regulations without scientific implementation overexpanded regulated area and focus on the discharge concentration of contaminated sources stimulated development of small size sources. To overcome these problems, we suggested reestablishment of regulated area, differentiation of regulation amendments, and flexibility in the application of regulation. It is necessary to arrange regulated area based on the efficient land use management and scientific implementation and then to mitigate land use regulation under the sustainable development. For the flexible application of regulation, it is required to amend the rule in response to the change of environmental condition and development of environmental techniques.

• Korean Journal of Environment and Ecology
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• v.23 no.6
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• pp.569-576
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• 2009

Sediment and nutrient loading caused by the removal of forest cover and alteration of agricultural lands in catchments have led to the deterioration in Lake Shirarutoro. To examine the effects of deforestation and agricultural activities on water quality, I examined changes in total nitrogen (TN) and total phosphorus (TP) of lake water induced by land use change, and compared them with the various research data produced over the years. Our investigation showed that the level of TN and TP in the lake water decreased when forest cover increased but increased when farmland area increased. The concentration of TN and TP was high in Lake Shirarutoro despite that its catchment was surrounded by large forests and small farmlands. This result indicates that land uses near Lake Shirarutoro have affected the quality of the lake water. I have examined the changes of sediment yield in the lake's catchment over the last approximately 300 years. Eleven core samples were obtained from the lake sediment and analyzed to establish a chronology after using two tephra layers (Ko-c2 in 1694 and Ta-a in 1739) and a $^{137}Cs$ peak (in 1963). The average sediment yield under the natural condition during the first two periods was 8.4 tons/$km^2$/year in 1694~1739 and 8.9 tons/$km^2$/year in 1739~1963 respectively. The conversion of the Shirarutoro catchment into agricultural lands and deforestation intensified, leading to an increased sediment yield of 21.1 tons/$km^2$/year during 1963~2007.

• Journal of Korean Society of Water and Wastewater
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• v.35 no.6
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• pp.507-516
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• 2021

In this study, the machine learning which has been widely used in prediction algorithms recently was used. the research point was the CD(chudong) point which was a representative point of Daecheong Lake. Chlorophyll-a(Chl-a) concentration was used as a target variable for algae prediction. to predict the Chl-a concentration, a data set of water quality and quantity factors was consisted. we performed algorithms about random forest and gradient boosting with Python. to perform the algorithms, at first the correlation analysis between Chl-a and water quality and quantity data was studied. we extracted ten factors of high importance for water quality and quantity data. as a result of the algorithm performance index, the gradient boosting showed that RMSE was 2.72 mg/m³ and MSE was 7.40 mg/m³ and R² was 0.66. as a result of the residual analysis, the analysis result of gradient boosting was excellent. as a result of the algorithm execution, the gradient boosting algorithm was excellent. the gradient boosting algorithm was also excellent with 2.44 mg/m³ of RMSE in the machine learning hyperparameter adjustment result.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.6
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• pp.794-800
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• 2004

The purpose of this study is to propose a method of controlling freshwater algae which grows abundantly and forms water bloom in the eutrophic water body with $H_2O_2$. Both laboratory and field methodologies were used. For the laboratory test $H_2O_2$ was injected into the different growth phases of incubated Microcystis aeruginosa and the resulting algae growth control rate was examined. For the field test, $H_2O_2$ was dispersed into a lake. Lake water quality was evaluated using a pre-test and post-test analysis of chlorophyll-a, luminance, transmittance, etc., which allowed a comparative evaluation of water quality change. From the experimental results, the growth of algae can be controlled with the small amount of 1mg/L of $H_2O_2$ at the lag phase of growth. The field test results show that the green colour of lake water was removed completely by the reduction of chlorophyll-a and improved transmittance, luminance, TKN, TP, TOC and SS. These indicators of water quality were improved significantly after $H_2O_2$ injection. Toxicity test results using the lake fish show no evidence of detrimental effect of $H_2O_2$ up to 15mg/L. The results of $EC_{50}$ with P. phosphoreum show that the toxicity of $H_2O_2$ was negligible compared to copper which was commonly used for algae control.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2002.10a
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• pp.433-436
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• 2002

A subwatershed within Juam Lake 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. Hydrologic response and pollutant load characteristics were analyzed based on observed data.