• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.3B
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• pp.221-230
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• 2009

In Korea, many water intake plants are easily affected by effluents of sewage treatment plants because sewage treatment plants are usually located upstream or nearby the plants of the same riverine area. Furthermore, the inflow of harmful contaminants owing to pollutant spills or transportation accidents of vehicles using the roads and bridges intersecting the river causes significant impact on the management of water intake plants. Paldang lake, the main water intake plants in Korea, is especially exposed to various water pollution accidents, because the drainage basin area is significantly large compared to the water surface area of the lake. Therefore it is necessary to predict the possible pollutant spill in advance and consider measurements in case of water pollution. In this study, water quality prediction was performed in Paldang Lake in Korea durig the dry season using two-dimensional numerical models. In order to represent the cases of pollutant accidents, the difference of pollutant transport patterns with varying injection points was analyzed. Numerical simulations for hydrodynamics of water flow and water quality predictions were performed using RMA-2 and RAM4 respectively. As a result of simulation, the difference of pollutant transport with the injection points was analyzed. As a countermeasure against the pollutant accident, the augmentation of the flow rate is proposed. In comparison with the present state, the rapid dilution and flushing effects on the pollutant cloud could be expected with increase of flow rate. Thus, increase of flow rate can be used for operation of water intake plants in case of pollutant spill accidents.

• Journal of Korean Society on Water Environment
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• v.27 no.5
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• pp.689-698
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• 2011

In South Korea, Total Maximum Daily Load (TMDL) has been enforced since 2004 to restore and manage water quality in the watersheds. However, the appraisal of TMDL in South Korea has lots of weaknesses to establish the plan for recovery of water quality because it just evaluates the target water quality during the particular flow duration interval. In the United States, Load Duration Curve (LDC) method bas been widely used in the TMDL to evaluate the water quality and pollutant loads considering variation of stream flow. In a recent study, web-based Load Duration Curve system was developed to create the LDC automatically and provide the convenience of use. In this study, web-based Load Duration Curve system was applied in the Gapyeongcheon watershed using the daily flow and 8-day interval water quality data, and Q-L Rating Curve was used to evaluate the water quality and pollutant load in the watershed, also. As a result of study, water quality and pollutant load in Gapyeongcheon watershed were met with water quality standard and allocated load in the all flow durations. Web-based Load Duration Curve system could be applied to the appraisal of South Korean TMDL because it can be used to judge the impaired flow duration and build up the plan of load reduction, and it could enhance the publicity. But, web-based Load Duration Curve system should be enhanced through addition of load assessment tools such as Q-L rating curve to evaluate water quality and pollutant load objectively.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1998.10a
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• pp.533-540
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• 1998

In this study, to propose the methods predicting water qualities in rural areas, the methods which were based on the runoff ratio, the relationships between the pollutant load(L) and the water runoff(Q), and the relationships between the runoff ratio and the water runoff in Bokha stream watersheds were examined. As a result, we had acquired reliable the values of runoff ratio and the reasonable equations between the pollutant load(L) and the water runoff(Q) in Bokha stream watersheds. And it was noticed that the runoff ratio had tendency of varying directly proportional to the water runoff.

• Proceedings of the KSRS Conference
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• 2002.10a
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• pp.506-506
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• 2002

S. Korean Government has accelerating its efforts to enhance the quality of the drinking water. The Ministry of Environment has declared the law of securing water-pollutant buffering zone to minimize the inflow of the point and nonpoint sources into the drinking water sources. As a first phase of installing nationa-wide water-pollutant buffering zone, approximately 300km buffering zone has been delineated along the South and North Han river, the major drinking water sources for the capital area of S. Korea, which has the population of more than 12 millions. The buffering zone has the width of 1,000 meter for the special protection area, and 500 meter for the remaining area from both ends of the river. The major works have been done in three stages. Firstly, the boundaries lines of the buffering zone was delineated on the digital topographic maps. Secondly, the maps were overlayed with the cadastral maps to identify individual land parcels, the street address of the major pollutant discharging facilities, and all different types of pollutants including livestocks. Thirdly, the field work has been done as a verification. Once the buffering zone was generated, all the information for the buffering gone were created or imported from other government agencies including official land price, details of the major manufacturing facilities discharging considerable amount of pollutants, major motels and resorts, not to mention of restaurants, etc. Also, major livestock houses were located to identify the path of the pollutant inflow to the drinking water source. Further works need to be continued such as purchasing private lands within the buffering zone and change the land use in the efforts to decrease the pollutant amount and to provide more environmentally friendly space. Also, high resolution satellite imagery should be utilized in the near future as a cost-effective data source to update all the landuse activities within buffering zone.

• Journal of Korean Society on Water Environment
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• v.32 no.2
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• pp.149-162
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• 2016

In recent years, there has been demand for precise estimations of pollutant loads on nationwide scale for the development of appropriate site specific (watershed specific) policies to reduce the negative impact of pollutant loads. River flow data and water quality data that were previously collected by various research institutes and universities for specific research purposes for a limited period was utilized in this study. However, only TMDL 8-day interval flow and water quality data were available in national scale. Three watersheds were selected and pollutant loads were calculated by two methods i.e., Numeric Integration (NI) method and Soil and Water Assessment Tool (SWAT). Subsequently, the results were compared to determine the appropriate method for monitoring nonpoint source networks nationwide. The SWAT model was calibrated and its estimated daily flow data were used in the NI method with estimated sediment data for 8-day monitoring data for three watersheds. The results indicated that the quantity of pollutant loads estimated with the NI and SWAT are different to some degrees especially during the summer season for all the three study watersheds. Thus, more frequent sampling of water quality is needed for nonpoint source pollutant estimation.

• Journal of Korean Society on Water Environment
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• v.25 no.2
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• pp.256-267
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• 2009

A method of estimating pollutant delivery ratios considering watershed physical and meteorological characteristics and flow conditions using SWAT-K watershed model was described, and pollutant delivery characteristics during dry and rainy seasons, for monthly and seasonally, and with flow regimes were investigated for the Chungju dam watershed. Delivery ratios for sediment, T-N, and T-P showed higher values over 100% during dry and winter seasons with low pollutant loads and flows, and showed relatively uniform ones under 100% during rainy and summer seasons with concentrated loads and flows. It was found that mainly wet flows during summer seasons played very important roles in investigating the delivery characteristics of total or nonpoint pollutant loads, because more than 90% of total loads were influenced by nonpoint source, and discharged with the flows. From the results, we could find out the delivery characteristics with various watershed and flow conditions which are difficult to consider by actual measurement, and could get a foothold of estimating more reasonable and scientific allocated loads for water quality standard using the reliable method of estimating delivery ratios with a watershed model.

• Journal of Korea Water Resources Association
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• v.34 no.5
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• pp.487-497
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• 2001

Investigated data on Lake Okjeong were used for the simulation of water quality. According to the simulation results, the effective scheme of water quality management on reservoir has been proposed. It has been recognized that the water quality of Lake Okjeong is under eutrophic and mesotrophic condition even though there are seasonal variation. The water quality of lake is mainly affected by the inflow of pollutant load from watershed. Therefore, to estimate and quantify the accurate amounts of pollutants flowing into reservoir is absolutely necessary for the effective management of water quality on Lake Okjeong. When the pollutant load measured during 7 different rainy periods in 1999 was compared with total pollutant load in 1999. TN and TP measured during 7 different rainy periods showed almost 50% of total pollutant load. In case of SS, it was 72.8%. On the other hand, the rainfall amount measured during the 7 different rainy periods was about 17.5% of total rainfall amount in 1999. Release rate of TP shows 11.92 mg/L at fish farm site and 0.2∼1.9 mg/L at monitoring station of water quality on Lake Okjeong, and which is considered to be less than that of other foreign reservoirs under the circumstances of anoxic condition. For the effective management of water quality on Lake Okjeong. WASP5 water quality simulation model has been applied and verified, and the verified model was used to propose the effective scheme of water quality management. In this case, 6 different scenarios were applied, by changing the amount of inflow of pollutant load in each subbasin. The most effective scheme has turned out that pollutant load generated from Imsil and Gwanchon subbasin should be reduced, and the best way to improve the water a quality is to reduce the pollutant load at every subbasin. According to the simulation result, wastewater treatment facility should be located at every subbasin.

• Journal of Environmental Impact Assessment
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• v.20 no.6
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• pp.833-843
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• 2011

The purpose of this study is to analysis pollutant loading of upper Nakdong River basin according to the variation of discharge. The correlation between discharge and pollutant concentration and between discharge and pollutant loading were analyzed by statistical method, respectively. Regression equation of pollutant loading and discharge was represented as $L=_aQ^b$ in which L = pollutant loading(kg/day), and b = regression coefficients, and Q = discharge($m^3/day$). The correlation coefficient of study area was in range of 0.8428 to 0.9935. The SS was the highest b value 1.2856~1.7730 among water quality parameters because the pollutant loading of SS was much affected by flow. Additionally, the applicability of the regression equations was verified by comparing predicted results with observed value. The correlation coefficient of verification was in range of 0.8983 to 0.9987 and NSEC was in range of 0.7018 to 0.9960. Therefore the pollutant loading was good correlated with discharge. The main result will be used as basic data for water quality management and design of environment fundamental facilities.

• 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.

• Proceedings of the KSRS Conference
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• 1999.11a
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• pp.63-69
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• 1999

The purpose of this study is to develop Water Quality Management System(WQMS), which performs calculating pollutant discharge and forecasting water quality with water pollution model. Operational water quality management requires not only controlling pollutants but acquiring and managing exact information. A GIS software, ArcView was used to enter or edit geographic data and attribute data, and MapObject was used to customize the user interface. PCI, a remote sensing software, was used for deriving land cover classification from 20 m resolution SPOT data by image processing. WQMS has two subsystems, Database Subsystem and Modelling subsystem. Database subsystem consisted of watershed data from digital map, remote sensing data, government reports, census data and so on. Modelling subsystem consisted of NSPLM(NonStorm Pollutant Load Model)-SPLM(Storm Pollutant Load Model). It calculates the amount of pollutant and predicts water quality. This two subsystem was connected through graphic display module. This system has been calibrated and verified by applying to Mokhyun stream watershed.