• Korean Journal of Soil Science and Fertilizer
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• v.40 no.1
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• pp.18-24
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• 2007

Paddy fields are apparently nonpoint source pollution and influence water environment. In order to improve water quality in rivers or lakes, to low nutrient load from paddy fields are required. To establish comprehensive plan to control agricultural non-point source pollution, it is imperative to get a quantitative evaluation on pollutants and pollution load from paddy fields. A field monitoring study was carried out to investigate the water balance and losses of nutrients from fields in Sumjin river basin. The size of paddy fields was 115 ha and the fields were irrigated from a pumping station. The observed total nitrogen loads from paddy fields were larger than those of the unit loads determined by Ministry of Environment data (MOE). It is because the nitrogen fertilization level at the studied field was higher than the recommended rate and the high irrigation and subsequent drainage amount. On the contrary, total phosphorus loads were less than those addressed by MOE since phosphorus fertilization level was lower than that of standard level. Therefore, it was found that fertilization, irrigation, and drainage management are key factors to determine nutrient losses from paddy fields. When the runoff losses of nutrients were compared to applied chemical fertilizer, it was found that 42 to 60% of nitrogen lost via runoff while runoff losses of phosphorus account for 1.3 to 7.6% of the total applied amount during the entire year.

• Journal of Environmental Science International
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• v.21 no.1
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• pp.31-39
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• 2012

The objective of this study is to provide pollutant loads delivery ratio for flow duration in Oenam-cheon watershed, which is upstream watershed of Juam Lake. To calculate the delivery ratio by flow duration, rating curves and discharge-loads curves using measured data were established, then Flow Duration Curve(FDC) and pollutant loads delivery ratio curves were constructed. The results show that the delivery ratios for $BOD_5$ for abundant flow($Q_{95}$), ordinary flow($Q_{185}$), low flow($Q_{275}$), and drought flow($Q_{355}$) were 23.9, 12.7, 7.1, and 2.9%, respectively. The delivery ratios of same flow regime for T-N were 58.4, 31.2, 17.2 and 7.1%, respectively. While, the delivery ratios T-P were 17.3, 7.5, 3.4, and 1.1% respectively. In general, delivery ratio of high flow condition showed higher value due to the influence of nonpoint source pollution. Based on the study results, generalized equations were developed for delivery ratio and discharge per unit area, which could be used for ungaged watershed with similar pollution sources.

• Journal of Environmental Policy
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• v.12 no.1
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• pp.37-58
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• 2013

In recently, the low impact development(LID) is discussed at various fields being related to urban stormwater, non-point source pollution, and quality of life. It is understood as an integrated development tool to induce sustainable development with various value-social, economic, and aesthetic. As concerning the development of waterfront area, the low impact development is interested in environmental planning. But the planning process and factors are not considered in precedent research. This study has two purposes. The one is to understand the planning process and factors of low impact development from literature review. The other is to apply the planning factors using case study and to know the effect of low impact development as the simulation plan. The simulation plan is based on some landuse planning. It is divided into the setting the region for environmental protection and the function of public facilities, spatial planning for enlarging permeable area, and spatial planning for circulation of water. The simulation model uses the LIDMOD2. The 14 planning factors of low impact development is applied to case region. And the effect is about 7~10 percent in reduction of nonpoint source pollution and surface runoff.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.1
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• pp.97-105
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• 2008

Nitrogen budgets in Korea in 2005 were estimated using a mass balance approach. Major nitrogen fluxes were divided into three sections: cities, agricultural area, and forest. Nitrogen inputs were chemical and biological fixation, dry and wet deposition, imported food and feed, while crop uptake, volatilization, denitrification, leaching, runoff, and forest consumption were nitrogen outputs. Non-point source(NPS) pollution budgets were also estimated by mass balance approach. Annual total nitrogen inputs budgets were 1,442,254 ton$\cdot$yr$^{-1}$, and outputs were 814,415 ton$\cdot$yr$^{-1}$. Approximately 19.4% of nitrogen input leaked to river and seawater as NPS pollution. It contains nitrogen input 21 percent more than the previous research in 2002. Especially the change of government plans affect nitrogen budget. As a result, in the output field, the whole nitrogen amount due to landfill reduce from 20 percent to less than 1 percent.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.2
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• pp.103-112
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• 2011

The main objective of this research was to estimate Nitrogen budget of South Korea in 2008. Input-output budgets for nitrogen fluxes were categorized into three sections: cities, agricultural area, and forest. Chemical and biological fixation, dry and wet deposition, imported food and feed were used as the nitrogen input. Crop uptake, volatilization, denitrification, leaching, runoff, and forest consumption were used as the nitrogen outputs. Annual total nitrogen input was 1,294,155 ton/yr, and output was 632,228 ton/yr. Comparison with a previous research in 2005 indicates that nitrogen input was decreased by 1.9% due to the decrease in nitrogen fertilizer while nitrogen output was decreased by 6.3%. Non-point source (NPS) pollution was also estimated by mass balance approach, which increased by 22% than the previous research in 2005. The emission of nitrous oxide ($N_2O$) caused by denitrification was newly examined in this research. About 8,289 ton/yr of $N_2O$ was released from agriculture area and domestic wastewater treatment plant.

• Journal of Wetlands Research
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• v.18 no.3
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• pp.292-300
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• 2016

Diverse and comprehensive countermeasures were established to prevent water pollution in coastal areas such as constructed wetlands(CW).This study was conducted to assess the water quality improvement through CW constructed along the shoreline of Hwaseong coastal reservoir. The CW is located in Hwaseong-si, Gyeonggi-do and consisted of a forebay and a wetland. The CW was monitored twice during rainy days and 10 times during dry days. The monitoring results indicated that in and out flowrates were highly correlated with COD and TN loads. COD, TN and TP concentrations in the forebay was lower during dry days than rainy days. However, concentration and mass removal efficiencies of COD, TN and TP were greater during rainy days. In addition, the volume flowing into the CW was less compared to the outflow during rainy days indicating that the CW efficiently reduced the runoff volume. The overall pollutant removal efficiency of the CW were at least 50% for TSS, 20 to 35% for TP, and 26 to 94% for TN. The data gathered may be used to improve the pollutant removal efficiency of the system in the future.

• Journal of Wetlands Research
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• v.17 no.2
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• pp.193-202
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• 2015

In this study, a long term monitering of nonpoint source pollution runoff is conducted at the area of transportation related and EMCs(Event Mean Concentrations) in terms of water quality items, such as BOD, $COD_{Mn}$, SS, T-N and T-P are determined for each not only runoff event and but also observation site. On the other hands, SWMM(Storm Water Management Model) model is constructed using the data collected in the transportation areas selected. Model calibration and verification of SWMM is carried out based on the data collected. And simulated EMCs was compared with observed EMCs by monitoring and prior studies. SWMM applicability estimation was Using the compared result. The results of simulation showed that BOD 5.787 ~ 14.475 mg/L, $COD_{Mn}$ 12.946 ~ 59.611 mg/L, SS 13.742 ~ 46.208 mg/L, T-N 2.037 ~ 5.213 mg/L, T-P 0.117 ~ 0.415 mg/L. And a differential between simulated EMCs and observed EMCs is too low so comparing result show high fit(BOD 4.27 %, $COD_{Mn}$ 4.87%, SS 2.31%, T-N 5.78%, T-P 14.45%). A results of compared with the prior studies, BOD and T-P are included range of prior studies, $COD_{Mn}$ and SS are lower than range of prior studies, T-N is higher than range of prior studies. Differential between simulated EMCs and prior studies EMCs was showing for survey seasonal and changing land-use, so from now on, EMCs of using the internal representatives value will be calculated by more monitoring toward various precipitation events.

• Journal of the Korean Association of Geographic Information Studies
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• v.8 no.2
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• pp.125-135
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• 2005

Generation and transport of nonpoint source pollution, especially sediment-associated pollutants, are profoundly influenced by hydrologic features of runoff. In order to identify pollutant export rates, hence, clear knowledge of rainfall-runoff relationship is a pre-requisition. In this study, performance of AnnAGNPS model was assessed based on the ability of the model to predict rainfall-runoff relationship. Three catchments, each under different nearly single land use, were simulated. From the results, it was found that the model was likely to produce better predictions for larger catchments than smaller catchments. Because of using the daily time scale, the model could not account for short durations less than 24 hours, especially high intensity events with multiple peak flow that significantly contribute to the generation and transport of pollutants. Since CN information for regional areas has not been built up, a careful selection of CN is needed to achieve accurate prediction of runoff volume. Storm distribution also found to be considered as an important calibration parameter for the hydrologic simulation.

• Journal of Korean Society on Water Environment
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• v.16 no.4
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• pp.491-499
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• 2000

Effluent concentration estimation equations for treatment wetland were reviewed with 3 -year experimental data. Four equations from USEPA, WPCF, Kadlec and Knight, and this study were applied to the over 100 data points of 1996 to 1999 study at the pilot plant in Konkuk University. The system was a subsurface flow type and consisted of 60cm depth of sand and reeds, and it worked continuously including winter with domestic sewage from school building. Generally, all the equations demonstrated reasonable agreement with experimental data and they could be used for design process if selected carefully. Among them, the equation from this study showed the best fit for the data. The reason might be not only the equation was derived from the experimental data, but also it included plant coverage parameter in the equation while others did not Plant coverage was proved to be an important parameter in the prediction of the treatment wetland system, and its inclusion in the estimation equation could improve the accuracy. Although existing equations could be used in the wetland design, pilot plant experiment for the anticipated condition and subsequent equation development can provide more reliable equation. It takes time to obtain meaningful data from wetland system. Therefore, timely onset of well organized study is recommended before large scale application of treatment wetland system to either point or nonpoint source pollution abatement.

• Journal of Korea Water Resources Association
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• v.42 no.4
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• pp.297-307
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• 2009

For reliable water quality simulation by semi distributed model, accurate daily runoff simulation should have preceded. In this study, newly developed channel routing method which is nonlinear storage method is combination of Muskingum routing method and variable storage routing method and temporally weighted average curve number method were applied for effect analysis of water quality simulation. Developed modules, which are added in SWAT models and simulation, were conducted for the Chungju dam watershed. The simulation result by each module applied effect. As a result of analysis contribute water quality modeling, nonlinear storage method is more effective than temporally weighted average curve number method. Nutrient loading discharge was affected by development of runoff delaying from improvement of channel routing, because of characteristics of nonpoint source pollution.