• Journal of Korean Society on Water Environment
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• v.24 no.4
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• pp.480-487
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• 2008

Spatial and temporal analyses of water qualities were performed for 11 monitoring stations located in Mangyung watershed in order to analyze the trends of monthly water quality data of Biochemical Oxygen Demand (BOD), Total Nitrogen (TN) and Total Phosphorus (TP) measured from 1995 to 2004. The long-term trends were analyzed utilizing Seasonal Mann-Kendall test, LOWESS and three-dimensional graphs were constructed with respect to distance and time. The graph can visualize spatial and temporal trend of the long-term water quality in a large river system. The results of trend analysis indicated that water quality of BOD and TN showed the downward trend. This quantitive and quantitative analysis is the useful tool to analyze and display the long-term trend of water quality in a large river system.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.452-456
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• 2010

Water is an indispensable input to human's existence and industrial production. In these days, people are getting more concerned about their health and the interest in the safety of drinking water has increased. In this situation, this paper attempts to measure the economic benefits of the tap water quality improvement. The study area was restricted to Busan, the second largest city in Korea, where local government is planning to implement a tap water quality improvement program. We apply a one-and-one-half bounded dichotomous choice contingent valuation (CV) method to obtain at least a preliminary evaluation of the benefits. CV is developed for valuing goods or services that cannot be valued either directly or indirectly from market observations and has been applied to several environmental goods. The CV survey was rigorously designed to comply with the guidelines for best-practiced CV studies. We surveyed a randomly selected sample of 400 households in Busan and asked respondents questions in person-to-person interviews about how they would be willing to pay for the water quality improvement. Respondents overall accepted the contingent market and were willing to contribute a significant amount (US$1.66), on average, per household per month. We can also calculate the aggregate value of the program which improves the water quality in Busan. This study is expected to provide policy-makers with useful information for evaluating and planning environmental policies relating specifically to water.

• 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 the Korea Academia-Industrial cooperation Society
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• v.12 no.3
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• pp.1465-1472
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• 2011

Water quality surveys has been performed to establish water quality improvement strategy for the lake Pyeungtaek, and WASP model was used to simulate to identify the effect of water quality improvement according to the reduction of pollutant loadings for the upstream watersheds. Assuming that present loadings was continued up to the future, the water quality of the lake was found to be getting worse resulting from the increase of pollutants due to the planned future development. In this study, we made various scenarios to predict the future water quality, scenario 6 made a large contribution to improve the lake water quality compared to others. Even the scenario 6, COD concentration of year 2016 in the lake was examined to be under the 4th rate of water quality level for the lake (COD less than 8 mg/L), similar to year 2021. Even though additional reduction of loadings for the scenario 6 was made, the water quality in lake was a little improvement, and was though to be inappropriate action in the economic point of view.

• Communications for Statistical Applications and Methods
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• v.17 no.1
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• pp.39-45
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• 2010

As the value of environment is increasing, the water quality has been a matter of interest to the nation and people. Research on water quality has been widely studied, but focused on geographical characteristic and river characteristics like inflow, outflow, quantity and speed of water. In this paper, two approaches to measure the similarity of sampling sites by using water quality data are discussed and compared with two-years empirical data of Yongdam-Dam. The existing method has calculated their similarities with principal component scores. The proposed approach in this paper use correlation matrix of water quality related variables and MDS for measuring the similarity, which is shown to be better in the sense of being clustering which is identical to geographical clustering since it can consider the time series pattern of water quality.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2005.10a
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• pp.509-514
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• 2005

Geumgang canal is planned to connect Geumgang lake with Saemangeum reservoir to accelerate desalinization and dillute polluted water in Saemangeum reservoir. The purpose of this study is to evaluate the variations of water quality by divesion of Geumgang lake flow to the Saemangeum reservoir. WASP5 model was used to estimate water quality concentration of Geumgang lake. Model calibration and verification was done for water quality data for 2001 and 2002. As a result of simulating water quality concentration for 4 scenarios, which was considered whether Geumgang canal will be built, there was little influence on water quality in Geumgang lake though Geumgang lake flow diverted to Saemangeum reservoir.

• 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.

• Korean Journal of Ecology and Environment
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• v.39 no.3 s.117
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• pp.285-295
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• 2006

Korean water quality standards for the protection of agricultural water uses were originally derived based on management of public water resource. They were not prepared to protect crop plants from contaminants, and therefore required water parameters in agricultural uses were excluded in current water quality standards. Korean water standards in river and lake have five levels, and level IV is correspondent to agricultural water uses. Currently, there is no Korean guidelines to protect crop plants from contaminants contained in agricultural water. In Canada, agricultural water guidelines are provided to protect crops from contaminants. In this study, agricultural water quality standards in Korea were compared with them in developed countries to evaluate the adequacy of Korean water quality standards for the protection of agricultural water uses. Additional water quality parameters in agricultural uses were also proposed. Suggested parameters include electric conductivity, sodium, chloride, boron, copper, iron, zinc, and microbiological quality, They are the required parameters to protect crop plants as well as human health. Current water quality standards in agricultural uses was not considered to be appropriate in terms of crop protection. Additional water parameters should be included in agricultural water quality standards.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1998.10a
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• pp.558-564
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• 1998

Flow rate, watertable and selected water quality of 2 small rural streams and 6 observation well located in Kangwon-do, Korea, were monitored land use of the watersheds was investigated to describe the trend of stream water quality for 2 years and groundwater quality for 1 year. Water qualities were analyzed with respect to BOD, SS, T-N, Nitrate, T-P and E-coli. Stream water quality and gorundwater quality directly concerned with the amount of rainfall and paddy fields. but water quality of watersheds is existed with other factor. Therefore, We have to continued monitoring and developing the best management practice.

• Journal of Korean Society on Water Environment
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• v.20 no.6
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• pp.685-691
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• 2004

Water quality forecasting with long term flow is important for management and operation of river environment. However, it is difficult to set up and operate a physical model for water quality forecasting due to large uncertainty in the data required for model setting. Therefore, relatively simpler stochastic approaches are adopted for this problem. In this study we try several multivariate time series models such as ARMAX models for the possible substitute for water quality forecasting. Those models are applied to the BOD and COD levels at Noryangin station, Han river, and also evaluated the effect of release from Paldang dam on them. Monthly BOD and COD data from 1985 to 1991 (7 years) are used for model building and another two year data for model testing. As a result of the study, the effect of improvement on water quality is much more effective combining with the water quality improvement of dam release than considering only increment of dam release in the downstream Han river.