• Journal of Korean Society on Water Environment
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• v.30 no.3
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• pp.351-360
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• 2014

The allocation of margin of safety (MOS) at a uniform rate to all areas of the unit watershed makes it very difficult to keep the load allotment stable in the area for lack of reduction measures like forest land. This study developed an equation to calculate margin of safety differentially according to the regional characteristics. The equation was formulated on the basis of the regional characteristic factors such as a load contribution factor for land use type and a site conversion factor for the unit watershed. The load contribution factor represents a contribution of loads from a particular land use. The site conversion factor was derived from the site conversion ratio of a unit watershed. Margin of safety for the non-point pollution load in the land use sector decreased by 20~25% in three river basins. The margin of safety in the unit watersheds with low site occupation ratios decreased in high rate, while in the unit watersheds with large urban area decreased in low rate. With the application of the differential margin of safety considering regional characteristics, not only the reduction of pollution loads can become lighter but also it can be easier to develop plans for Total Maximum Daily Loads (TMDLs) even where the reduction measures are not available.

• Journal of Korean Society on Water Environment
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• v.24 no.4
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• pp.452-457
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• 2008

Nonpoint source (NPS) pollution is caused by rainfall moving over and through the ground. As the runoff moves, it picks up and carries away various pollutants from NPS. The discharge pattern of NPS pollutant loads is affected by the distribution of the rainfall during the year. This study analysed relationship between the rainfall event and the stream flow rate, and estimated the rainfall discharge ratio on the specific design flow which can be used as nonpoint discharge coefficient for the estimation of NPS pollution load. It is considered that nonpoint discharge coefficient can be effectively used for the calculation of NPS pollution load at the time of water quality modelling for the management of Total maximum daily load (TMDL).

• Journal of Environmental Health Sciences
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• v.27 no.2
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• pp.119-126
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• 2001

The key point in establishing water quality management measures is how to decide the load reduction for pollution sources. This study was performed to compare reduction methods for BOD loadings to achieve water quality standards at the end of the Yeongsan river. The target year is 2006 and 2011 and reduction methods are uniform treatment and treatment by influence rate. Using QUAL2E model, the study was performed under the conditions of establishing and non-establishing the publicly owned treatment works(POTWs). Uniform treatment which allocate the same reduction rate to pollution sources showed that all streams into the river should be applied for the reduction. However, treatment by influence rate which allocate the reduction rate by the order of influence rate showed that achieving target quality might be possible with a few streams for the reduction. But total amount of load reduction of streams was not significantly different from two methods.

• Journal of The Korean Society of Agricultural Engineers
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• v.50 no.2
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• pp.65-71
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• 2008

A monsoon season monitoring data from June to September, 2005 of a small forested watershed located at the upstream of the North Han River system in Korea was conducted to analyze the flow variations, the NPS pollutant concentrations, and the pollution load characteristics with respect to sampling frequencies. During the 4-month period, 1,423 mm or 79.2% of annual rainfall(1,797 mm) were occurred and more than 77%, 54% and 68% of annual T-N, $NO_3$-N and T-P loads discharged. Flow rate was continuously measured with automatic velocity and water level meters and 58 water quality samples were taken and analyzed. It was analyzed that the flow volume by random measurement varied very widely and ranged from 79% to 218% of that of continuous measurement. It was recommended that flow measurement of small forested watersheds should be continuously measured with automated flow meters to precisely measure flow rates. Flow-weighted mean concentrations of T-N, $NO_3$-N and T-P during the period were 2.114 mg/L, 0.836 mg/L, and 0.136 mg/L, respectively. T-N, $NO_3$-N and T-P loads were sensitive to the number of samples. And it was analyzed that in order to measure the pollution load within the error of 10% to the true load, the rate of sampling frequency should be higher than 89.7% of the sample numbers that were required to compute the true pollution load. If it is compared to selected foreign research results, about 10 water samples for each rainfall event were needed to compute the pollution load within 10% error. It is unlikely in Korea and recommended that thorough NPS pollution monitoring studies are required to develop the standard monitoring procedures for reliable NPS pollution quantification.

• Journal of Korean Society on Water Environment
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• v.39 no.4
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• pp.316-328
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• 2023

In this study, the characteristics of nonpoint pollutant outflow and contribution rate of pollution in Songya-stream mainstream and tributaries were analyzed. Further, water pollution management and improvement measures for pollution-oriented rivers were proposed. An on-site investigation was conducted to determine the inflow of major pollutants into the basin, and it was found that pollutants generated from agricultural land and livestock facilities flowed into the river, resulting in a high concentration of turbid water. Based on the analysis results of the pollution load data calculated through actual measurement monitoring (flow and water quality) and the occurrence and emission load data calculated using the national pollution source survey data, the S3 and S6 were selected as the concerned pollution tributaries in the Songya-stream basin. Results of cluster analysis using Pearson correlation coefficient evaluation and Density based spatial clustering of applications with noise (DBSCAN) technique showed that the S3 and S6 were most consistent with the C2 cluster (a cluster of Songya-stream mainstream owned area) corresponding to the mainstream of Songya-stream. The analysis results of the major pollutants in the concerned pollution tributaries showed that livestock and land pollutants were the major pollutants. Consequently, optimal management techniques such as fertilizer management, water gate management in paddy, vegetated filter strip and livestock manure public treatment were proposed to reduce livestock and land pollutants.

• Journal of Korean Society on Water Environment
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• v.31 no.6
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• pp.732-738
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• 2015

Water quality in four major river basin in Korea was managed with Total Maximum Daily Load (TMDL) System. The unit watershed in TMDL system has been evaluated with Target Water Quality (TWQ) assessment using average water quality, without considering its volume of water quantity. As results, although unit watershed are obtained its TWQ, its allocated loads were not satisfied and vice versa. To solve these problems, a number of TWQ assessments with using Load Duration Curve (LDC) have been studied at other watersheds. The purpose of this study was to evaluate achievement of TWQ with Flow Duration Curve (FDC) and Load Duration Curve(LDC) at 26 unit watersheds in Han river basin. The results showed that achievement rates in TWQ assessment with current method and with LDC were 50~56 % and 69~73%, respectively. Because of increasing about 20% of achievement rates with using LDC, the number of exceeded unit watershed at Han river Basin was decreased about 4~6 unit watersheds.

• Journal of Korean Society on Water Environment
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• v.37 no.4
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• pp.249-262
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• 2021

This study investigated the pollution characteristics of the main pollution zone in the Hwangguji watershed and the influence of the tributary on the main stream. The characteristics of the main pollution zone, including, the water quality index (WQI), stream rating, load duration curve (LDC), delivery load density (DLD), and contribution of the tributary to the mainstream, were evaluated by time-series visual heatmap. The WQI of the mainstream of Hwangguji was lowered to the poor (IV) level from the inflow point of Suwon stream (SW) and the LDC excess rate in the T-P was higher than that of BOD₅, especially for the wet season, suggesting that management of non-point source with T-P is preferred. The contribution (%) of the tributaries in the upstream section of Hwangguji watershed were BOD₅ 14.54%, TOC 15.67%, T-N 5.43%, and T-P 6.97%. In particular, the Suwon sewage treatment plant located in the mainstream showed a high contribution of BOD₅ (64.40%) and T-P (53.54%), respectively, due to the high discharge rate (6.019 m³/sec). Meanwhile, Sammi and Gal stream have a large impact on the mainstream with high DLD and poor WQI. Thus, both streams were considered as pollution hot spots. These results provide useful basic data for preparing more effective water quality improvement and management plans in the watershed.

• Journal of The Korean Society of Agricultural Engineers
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• v.57 no.2
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• pp.27-36
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• 2015

The objective of this paper was to quantitatively analyze the effect of concentrated animal feeding operations (CAFO) NPS pollution on a small watershed water quality. Monitoring was conducted from March to October, 2013. Monthly flow rate and selected water quality at each monitoring site were measured during dry days. Rainy day monitoring also was conducted. Modeling was conducted to evaluate the effect of CAFO NPS pollution on the water quality at the watershed outlet. The highest and mean concentration of selected water quality indices during rainy days were higher than those in dry days in general. The highest TN concentration measured at the CAFP pollution discharge point was 237.831 mg/L. The results revealed that the CAFO NPS pollution sources could be equally blamed for the water quality degradation of the stream. However, the effect of the NPS pollution from CAFOs seemed not to be very influential to the watershed water quality at the outlet. SWAT modeling revealed that the TN load was reduced by 18.95 %, 23.39 % and 30.53 % at the watershed outlet if the TN load at the CAFO NPS pollution discharge point reduced by 20 %, 40 % and 60 %, respectively. It was thought that the natural attenuation processes played an important role. The modeling was based only on the assumption of the load reduction and not verified by the monitored data. Therefore, it was suggested that a long term monitoring studies for the evaluation of the impact of CAFO NPS pollution on the watershed water quality be conducted.

• Journal of Korean Society on Water Environment
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• v.22 no.6
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• pp.977-981
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• 2006

In order to improve water quality in drinking water sources, Ministry of Environment (MOE) was implemented total water pollution load management (TWPLM) in all the major river basins. From the experience of the application of TWPLM, we could find some problems relating the target watershed, standard operating procedure (SOP) of establishment and implementation plan, water quality and flow rate, design flow, water quality model, margin of safety (MOS), and estimation of wasteload were found. The authors were reviewed ongoing TWPLM and presented the improvement schemes for a successful TWPLM. For the application of these suggestions, further detailed studies should be done to implement TWPLM in the future.

• Journal of Environmental Science International
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• v.25 no.2
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• pp.323-329
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• 2016

In this study, the applicability of MBR process was evaluated to improve processing of personal sewage treatment facilities of $50m^3/day$ or less. As result of the research, stable discharge water quality could be secured as result of the MBR effector operation according to rate of inflow and inflow load and treatment efficiency of 98% or higher was shown by the membrane filtering method operation for SS, $BOD_5$. it was found that high treatment efficiency of 99% or higher. It is judged that detention time can be designed until 6.9 hr when applying MBR process on personal sewage treatment facilities with high pollution load and that cutback of pollution load can be possible through this study. It was shown that MBR process application reduces an annual cost of 4,829,600 won based on the basic unit calculation results and solves burden of amount of borne by causers according to excess of discharge water quality standards.