• 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.29 no.3
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• pp.343-353
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• 2013

Flow duration curve (FDC) can be developed by linking the daily flow data of stream flow monitoring network to 8-day interval flow data of the unit watersheds for the management of Total Maximum Daily Loads. This study investigated the applicable method for the development of long term FDC with the selection of the stream flow reference sites, and suggested the development of the FDC in 4 river basins. Out of 142 unit watersheds in 4 river basins, 107 unit watersheds were shown to estimate daily flow data for the unit watersheds from 2006 to 2010. Short term FDC could be developed in 64 unit watersheds (45%) and long term FDC in 43 unit watersheds (30%), while other 35 unit watersheds (25%) were revealed to have difficulties in the development of FDC itself. Limits in the development of the long term FDC includes no stream monitoring sites in certain unit watersheds, short duration of stream flow data set and missing data by abnormal water level measurements on the stream flow monitoring sites. To improve these limits, it is necessary to install new monitoring sites in the required areas, to keep up continuous monitoring and make normal water level observations on the stream flow monitoring sites, and to build up a special management system to enhance data reliability. The development of long term FDC for the unit watersheds can be established appropriately with the normal and durable measurement on the selected reference sites in the stream flow monitoring network.

• Journal of Environmental Impact Assessment
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• v.17 no.1
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• pp.47-56
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• 2008

Total Maximum Daily Load(TMDL) is a core basin management system to assign total emissions of pollutants to unit basin and emission source within a limit of the target water quality and to secure sustainability. considering "Environment and development" together. By current technical guidance of TMDL, the water quality in the riverbed of which the target water quality is noticed, must achieve the target; and the water quality standard for evaluating achievement of the target should be prescribed as non-excessive probability quality of water on the basis of the pertinent water quality documents. Therefore, the study calculated the target water quality by each unit basin which the target water quality must be noticed through the analysis of probability for water quality documents in rivers at the time of establishing a plan, and the study evaluated the achievement possibility of the target water quality by analyzing and comparing the target water quality plan with the standard water quality to evaluate the achievement of the target water quality. As the result, applying the proposed method to Mihocheon River system, it is concluded that selected the target water quality (Each BOD 3.3mg/1 and BOD 3.0mg/1) in Miho A and Musim A is available. Of course, it showed that the target water quality: BOD 2.5mg/1 in Miho A and BOD 3.0mg/1 in Musim A, could be achieved if the small reduction in B unit area was implemented.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.166-166
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• 2017

현재 우리나라에서 많은 연구에 활용되고 있는 오염부하지속곡선(Load duration curve, LDC)은 단일 기준유량의 문제점을 개선하기 위해 전체 유량 범위를 고려한 수질오염총량관리제(Total Maximum Daily Loads, TMDL) 평가 기법으로 개발되었다(Choi et al., 2012). LDC를 이용해 목표수질 달성여부를 분석하기 위해서는 일유량자료를 바탕으로 유량지속곡선(Flow Duration Curve, FDC)의 작성이 선행되어야 하는데(Park and Oh, 2012), 365일 연속적으로 측정된 실측 자료를 이용하는 것이 가장 확실하고 정확한 방법이다. 그러나 현재 환경부에서는 총량관리 단위유역에서 8일 간격으로 실측 유량 및 수질 측정이 이루어지고 있고, 특히 주로 비강우 시에 측정이 이루어지고 있는 실정이기 때문에 고유량에 대한 모니터링 자료가 부족한 실정이다. 이 같은 이유로 많은 연구에서 불연속적인 평균 8일 간격 유량을 그대로 사용하거나 일유량자료를 확보하기 위해 다양한 방법을 이용하고 있다. 그러나 이러한 유량자료의 변동은 유랑지속곡선에 변화를 주고 결과적으로는 LDC를 이용한 목표수질 달성여부를 판단함에 있어 불확실성이 있다. 이에 본 연구의 목적은 환경부 총량측정망 8일유량자료와 이와 연계성이 있는 국토교통부 하천유량 측정망 일유량자료를 이용하여 각각의 LDC를 작성하고, 이러한 일유량과 8일유량 사용이 LDC를 이용하여 목표수질에 대한 오염부하 특성분석에 어떠한 영향을 미치는지 유량 조건별로 차이를 비교분석하는 데 있다.

• Proceedings of the Korea Society of Environmental Biology Conference
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• 2002.05a
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• pp.78-78
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• 2002

• Journal of Korean Society on Water Environment
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• v.30 no.3
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• pp.340-350
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• 2014

Recently, TMDL has been implemented to estimate the amount of pollutant loads and to establish proper mitigation strategy to decrease the pollutant loads by the Ministry of Environment. To estimate the amount of pollutant loads with reasonable accuracy, securing landcover map with periodically updating is essential. However, in reality, due to the technical and financial difficulties, the landcover map has not been updated annually. Hence, this study mainly aims to suggest an effective GIS-based updating method in order to promote utilization of landcover map in the estimation of pollutant loads. Bupyeong-gu at the City of Incheon with the total area of $31.98km^2$ was chosen for this study and spatial data including digital topographic maps, ortho aerial photo, and satellite images were collected and utilized. A total of 7,235 feature entities were newly produced through the updating process of five steps and it was revealed that the classification of landcover with the total area of $3.34km^2$ was to be changed. The validity and feasibility of the suggested method were proved with the accuracy of 97.9% from the field verification. Further study needs to be made for devising more automated method to update landcover map to facilitate TMDL for individual local governments.

• Journal of Korean Society on Water Environment
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• v.31 no.3
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• pp.295-303
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• 2015

In Korea, Total Maximum Daily Loads(TMDLs) has been enforced to restore and manage water quality in the watersheds. However, some assesment of implementation plan of TMDLs showed that the achievement of the target water quality is not related to the proper allocation loads because difference of flow duration interval. In the United States, the discharge loads are determined by water quality modeling considering standard flow conditions according to purpose. Therefore, this study tried to develop the allocation method considering economical efficiency using water quality model. For this purpose, several allocation methods being used in the management of TMDLs is investigated and develope an allocation criteria considering regional equality and uniformity. Since WARMF(Watershed Analysis Risk Management Framework) model can simulate the time varying behavior of a system and the various water quality variables, it was selected for a decision support system in this study. This model showed fairly good performance by adequately simulating observed discharge and water quality in Miho watershed. Furthermore, the scenario simulation results showed that the effect of annual average water quality improvement to remove 1kg BOD is more than 25 times, even if point pollutants treatment facility is six times more expensive to operate than non-point pollutants treatment facility.

• Journal of Korean Society on Water Environment
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• v.29 no.3
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• pp.393-399
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• 2013

To control organic matters, it needs to manage not only biodegradable organic matters but also refractory organic matters. Refractory organic matters from municipal wastewater, industrial wastewater, non-point sources and etc., have been continuously discharged to the near watersheds. It is estimated that the refractory organic matter ratios are continuously increased in waterbody. In watersheds of the Total Maximum Daily Loads (TMDLs), it was investigated that COD/BOD ratios increased in many unit watersheds of the 4 major river basins. The portions COD/BOD ratios increased were found to be a 97% of Geum River unit watersheds, a 81% of Yeongsan/Seumjin River unit watersheds, a 78% of Nakdong River unit watersheds, a 70% of Han River unit watersheds, respectively. Therefore, it has become important for establishment of effective management strategies to control refractory organic matter in watersheds of the Total Maximum Daily Loads (TMDLs). In order to properly manage organic matters including refractory organic matters, the present organic indicator (BOD) has to be converted to TOC (or COD). Compared to COD and BOD, TOC, as a organic matter indicator, is evaluated more appropriate.

• Journal of Korean Society on Water Environment
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• v.29 no.4
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• pp.531-539
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• 2013

In order to apply a water quality indicator as a certain target pollutant, the indicator should have the representability of an index for the management of Total Maximum Daily Loads (TMDLs). Scientific groundwork and treatment technologies also should be provided for the application of the indicator. This study analyzed the applicability of major water quality indicators for target pollutants. The results showed that four water quality indicators of TOC, T-N, SS & T-Coli can be considered as target pollutants besides existing BOD and T-P. These indicators can be applied with the preparations such as essential basic data, pollution load estimation framework as well as legal criteria setting when the need is raised. As the importance of TOC, which is considered as a replacement of BOD, is emphasized, technical and institutional terms are being prepared in order to determine TOC as another target pollutant in the near future. It could be considered to combine TOC with BOD for the time being during the $3^{rd}$ stage of TMDLs in view of the present conditions for the management of TOC. TOC can be the most effective index for the organic matter and help to be managed more systematically in the waterbodies where rivers and lakes are mutually connected.

• Journal of Korean Society on Water Environment
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• v.28 no.6
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• pp.859-865
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• 2012

It is necessary to evaluate performances hitherto carried out in the management of Total Maximum Daily Loads (TMDLs) and to set up direction so that this system can be improved continuously in the future. This study was investigated load allocation achievement ratio, water quality goal achievement ratio and interrelation between water quality goal and load allocation for the first period (2004~2010). Load allocation achievement and BOD water quality goal achievement ratio were 50% and 73% in Guem River Basin, respectively. The main reason for excess of load allocation and shortfall of water quality goal were unfulfilled reduction plan and pollution sources increment. Therefore, it is necessary to develop enhanced pollution sources prediction method and make a list realizable reduction plan. 63% of the unit watershed was not interrelation between water quality goal and load allocation. The reason why water quality goal and load allocation had not correlation were water quality of upper unit watershed, increment of inflow quantity, effluent water quality of wastewater treatment plant affected the unit watershed, increment of inner productivity by algae, water quality deterioration during the specific period, river management flow, etc.