• Journal of Korean Society of Water and Wastewater
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• v.25 no.5
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• pp.751-757
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• 2011

The monitoring technique based on electrical conductivity (EC) can provide researchers with some advantages in maintenance management and is cost-effective as compared with existing CSOs monitoring. In this study, the flow rate estimation using EC data was executed in two sites where storm overflow chamber had installed. In the result of A-site, R2 of second order multinomial between dilution ratio of EC and observed flow rate was showed the range of 0.68 ~ 0.77. And $R^{2}$ of B-site was 0.62 ~ 0.81. On the other hand, cumulative frequency of A-site was 43.4 ~ 52.2% in the relative error level of under 20%. And B-site was 10.1 ~ 46.5%. The flow rate estimation formula was improved through consideration of some parameters including antecedent dry days and rainfall duration. And difference between estimated flow rate and observed flow rate in total rainfall event was very small.

• The Journal of Engineering Geology
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• v.19 no.3
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• pp.365-371
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• 2009

This paper address the characteristics of loading pollutants caused by the unit agricultural area to establish an efficient management method in NPS (non-point source). The relationship between rainfall and runoff shows good coefficient with 0.92, when the event which shows relatively long antecedent dry days is excepted. The impact of runoff volume on the runoff coefficient can be described by the rainfall intensity strongly. The pollutant EMCs (event mean concentrations) in runoff increased by the increase of antecedent dry days due to dry soil conditions. As the similar pattern of pollutant's loads such as TSS, BOD, COD, TN and TP, it is cleared that other pollutants can be removed when TSS is removed. Therefore the system using only runoff coefficients is not sufficient for the prediction of pollutant loads. It is necessary to consider soil conditions such as rainfall, antecedent dry day, antecedent rainfall etc. for the prediction system.

• Journal of Korean Society on Water Environment
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• v.20 no.5
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• pp.415-421
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• 2004

Litter wastes on highway runoff are gradually being considered one of the major pollutants of concern in protecting the integrity of receiving waters for beneficial use. The California State Water Resources Control Board has identified in their 303(d) list at least 36 water bodies where trash or litter is considered a pollutant of concern. The first TMDL adopted by the Region 4 (Los Angeles area) of the California State Water Quality Control Board was for trash in the Los Angeles River. The first flush characteristic study was developed to obtain first flush water quality and litter data from representative stormwater runoff from standard highway drainage outfalls in the Los Angeles area. Total captured gross pollutants in stormwater runoff were monitored at six Southern California highway sites over two years. The gross pollutants were 90% vegetation and 10% litter. Approximately 50% of the litter was composed of biodegradable materials. The event mean concentrations show an increasing trend with antecedent dry days and a decreasing trend with total runoff volume or total rainfall. Event mean concentrations were ranged 0.0021 to 0.259g/L for wet gross pollutants and 0.0001 to 0.027g/L for wet litters. The first flush phenomenon was evaluated and the impacts of various parameters such as rainfall intensity, drainage area, peak flow rate, and antecedent dry period on litter volume and loading rates were evaluated. First flush phenomenon was generally observed for litter concentrations, but was not apparent with litter mass loading rates. Litter volume and loading rates appear to be directly related to peak storm intensity, antecedent dry days and total flow volume.

• Journal of Environmental Impact Assessment
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• v.16 no.6
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• pp.525-532
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• 2007

In order to establish and implement the total maximum daily load (TMDL) management plan in Korea, it is necessary to set the source units and calculate discharge loads for non-point source pollutants such as BOD, COD, SS, TN and TP. This study analysed the corelation between stormwater runoff characteristics and event mean concentrations (EMCs) of non-point source pollutants. As the result of the corelation analysis, we knew that all the antecedent dry days (ADD) and the rainfall correlated lowly with non-point source pollutants in the urban areas such as resident area, industrial area, business area, road area and parking area. Therefore, it is necessary to get all samples from stormwater starting point to stormwater ending point and standardize the sampling method of stormwater in order to obtain more accurate EMCs for landuse.

• Journal of Environmental Impact Assessment
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• v.23 no.1
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• pp.67-74
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• 2014

The aim of this study was evaluated the effects of total rainfall, rainfall intensity and antecedent dry days and identify the correlation analysis with the EMC removal efficiency, in order to provide an understanding of the operation and maintenance factors of constructed wetland in flood pumping station. This study was conducted total of 20 monitoring in a catchment(326.2 ha) of constructed wetland in Ga-un flood pumping station located at the downstream of the Wang-suk stream. The determined EMC removal efficiencies were $36.04{\pm}9.45%$ for BOD, $38.50{\pm}13.50%$ for $COD_{Mn}$, $34.34{\pm}13.05%$ for TN and $34.22{\pm}14.27%$ for TP, respectively. These results showed that the pollutants concentration and EMC were reduced while passing through the constructed wetland. In the correlation analysis, the highly correlations with EMC removal efficiency of BOD and $COD_{Mn}$ were observed for total rainfall and rainfall intensity (P<0.05). However, the correlations were not found with TN and TP for rainfall variables.

• Journal of Wetlands Research
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• v.25 no.4
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• pp.221-229
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• 2023

Extracted from the metropolitan area, the Paldang Lake, which supplies approximately 8 million tons of water, has achieved a BOD (Biochemical Oxygen Demand) of 1.1 mg/L as a result of water quality preservation policies. However, concerning the COD (Chemical Oxygen Demand) component that encompasses refractory organic matter, there has been an observable upward trend in concentration. The introduction of refractory organic matter into the water source of Paldang Lake brings potential increments in BOD, generates off-putting tastes and odors in tap water, increases THM (Trihalomethane) formation, and triggers algae proliferation. Moreover, if residual hazardous refractory pollutants persist in aquatic environments, they may induce endocrine disruption and phenomena such as antibiotic resistance. In this study, a monitoring campaign was executed to discern the concentration of refractory organic matter emissions from point and non-point sources within Paldang Lake and its upstream region, with the aim of managing refractory organic matter in Paldang Lake. By comparing refractory organic matter emission concentrations across monitored areas, the elimination efficiency at wastewater treatment plants was assessed. Additionally, employing the Pearson correlation correlation analysis technique, correlations among refractory organic matter indices, antecedent wet days, and antecedent dry days were explored. The concentrations of refractory organic matter in rivers and Paldang Lake exhibited a similar pattern. Wastewater treatment plant effluents exhibited higher concentrations compared to rivers and Paldang Lake. The assessment of refractory organic matter removal at wastewater treatment plants indicated a removal efficiency of 65.73%. However, no significant correlation emerged between refractory organic matter emission concentration and antecedent wet days or priory antecedent dry days. This absence of correlation is attributed to data scarcity, underscoring the need for long-term monitoring and data accumulation.

• KIEAE Journal
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• v.16 no.1
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• pp.67-71
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• 2016

Purpose: There is a growing interest in rainwater runoff reduction effect of green roof, as flooding caused by increasing impervious surface is becoming more and more frequent in urban areas. This study was conducted to prove runoff reduction and runoff delay effect of the retentive green roof and to investigate its influencing factors to the rainfall events that occurred in the summer of 2013. Method: The experiment intended to monitor the runoff quantity of the retentive green roof($140m^2$) and normal roof($100m^2$) in #35 building in Seoul National University, Seoul, Korea for 75 days in 2013. Result: On analysis of 9 rainfall events, it showed that the retentive green roof has 24.8~100% of runoff reduction ratio, 21.2~100% of peak flow reduction ratio, 0.5~3.75 hours of peak delay, and $1.8{\sim}7.2m^3$ of retaining capacity in an area of $140m^2$. It shows different results depending on rainfall and antecedent dry days. The results show that runoff reduction effect is effective when the rainfall is less than 50 mm and antecedent dry day is longer than five days on average. By installing retentive green roofs on buildings, it can help mitigate urban floods and rehabilitate urban water cycle.

• Journal of Wetlands Research
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• v.10 no.2
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• pp.105-114
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• 2008

Growth in population and urbanization has progressively increased the loadings of pollutants from non-point sources as well as point sources. Separated sewer overflows(SSO) have been considered as a major cause of water-quality deterioration of natural water-courses in the vicinity of the heavily urbanized areas. The factors defining the magnitude and occurrence of SSO are site-specific. It is important to know exact properties of pollutants contained in SSO to address water quality impacts that are caused by SSO inputs to the receiving waters. Site and event parameters found to have significant influences on urban runoff pollutant EMCs include total event rainfall, antecedent dry period, rainfall intensity. In this study, a field survey was carried out in some selected areas of Cheongju city. Literature from previous similar studies was consulted and some important factors affecting the runoff characteristics of urban drainage areas were analyzed for some selected survey points. It was found that the factors most affecting BOD are the number of dry days prior to rainfall and the intensity of the rainfall. The factor most affecting CODcr is the number of dry days prior to rainfall. The factors most affecting SS are the amount of rainfall and the number of dry days prior to rainfall. The factor most affecting TN is the amount of rainfall. The factor most affecting TP is the amount of rainfall and the number of dry days prior to rainfall.

• Membrane and Water Treatment
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• v.10 no.1
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• pp.45-55
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• 2019

Climate change has significantly affected the rainfall characteristics which can influence the pollutant build-up and wash-off patterns from the catchment. Therefore, this study explored the influence of varying rainfall characteristics on urban and agricultural runoff pollutant export using statistical approaches. For this purpose, Mann-Kendall and Pettitt's test were applied to detect the trend and breakpoint in rainfall characteristics time series. In addition, double mass curve and correlation analysis were used to drive the relationship between rainfall-runoff and pollutant exports from both catchments. The results indicate a significant decreased in total rainfall and average rainfall intensity, while a significant increased trend for antecedents dry days and total storm duration over the study periods. The breakpoint was determined to be 2013 which shows remarkable trend shifts for total rainfall, average rainfall intensity and antecedents dry days except total duration. Double mass curve exhibited a straight line with significant rainfall-runoff relationship indicates a climate change effect on both sites. Overall, higher pollutant exports were observed at both sites during the baseline period as compared to change periods. In agricultural site, most of the pollutants exhibited significant (p< 0.05) association with total rainfall, average rainfall intensity and total storm duration. In contrast, pollutants from urban site significantly correlated with antecedent dry days and average rainfall intensity. Thus, total rainfall, average rainfall intensity and total duration were the significant factors for the agricultural catchment while, antecedents dry days and average rainfall intensity were key factors in build-up and wash-off from the urban catchment.