• 한국물환경학회지
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• 제34권1호
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• pp.33-45
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• 2018

In this study, we discussed the application of Watershed model and Load Duration Curves (LDC) in Total Water Load Management System. The Flow Duration Curves (FDC) and the LDC were generated using the results of the daily HSPF model and analyzed on monthly or yearly flow duration variability, and non-point pollutant discharge loads by entire flow conditions. As a result of the calibration and verification of the HSPF model, both the flow and the water quality were appropriately simulated. The simulated values were used to generate the Flow Duration Curve and the Load Duration Curve, and then the excess rate by entire flow conditions was analyzed. The point and non-point pollutant discharge loads for entire flow conditions were calculated. It is possible to evaluate the variability of water quality in specific flow duration through the curves reflecting the flow duration variability and to confirm the characteristics of the pollutant source. For a more scientific Total Water Load Management System, it is necessary to switch from a current system to a system that can take into account the entire flow conditions. For this, the application of the watershed model and load duration curve is considered to be the best alternative.

• 한국물환경학회지
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• 제37권3호
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• pp.175-189
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• 2021

In this study, 48 streams in the Sapgyo Watershed were selected, and the Load Duration Curves (LDC) were drawn up for each stream using water quality and flow monitoring over the last three years (2018-2020), and it was evaluated whether the target water quality was achieved for each flow section. As a result of evaluating whether or not the target water quality exceeded according to the LDC, it was found that 22 rivers exceeded the target water quality. Five rivers exceeded the target water quality due to point pollutant sources, 13 rivers exceeded the target water quality due to non-point pollutant sources, and 4 rivers exceeded the target water quality due to both point and non-point pollutant sources. Among the rivers that exceeded the target water quality due to point pollutant sources, which included domestic sewage of the untreated population, there is a need to reduce the influx of polluted loads by the untreated population. The use of eco-friendly fertilizers is recommended for rivers with a relatively high farmland ratio among rivers exceeding the target water quality due to non-point pollutant sources, and installation of boiling point reduction facilities that can reduce the amount of polluted load introduced during rainfall or manage water shores. In rivers with a large number of livestock breeding heads, the livestock houses located in these rivers need to be preferentially transferred to livestock manure treatment plants. Due to the high ratio of land area because of urbanization, initial rainwater treatment facilities are required to reduce the amount of pollutant load flowing into the river through the impermeable layer during rainfall.

• 상하수도학회지
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• 제27권4호
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• pp.429-438
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• 2013

This study was to develop effective water quality management measures using LDC (Load Duration Curve) curves for TMDL (Total Maximum Daily Loads) unit watershed. Using LDC curves, major factors for BOD and T-P concentration loads generation (i.e. point source or non-point source) in the case study area (Geumho river basin) were found for different hydrologic conditions. Different measures to deal with the pollutant loads were suggested to establish BMPs (Best Management Practices). It was found that the target area has urgent T-P management methods especially at moist and midrange hydrologic conditions because of point source pollutants occurred in developed areas. One example measure for this could be establishment of advanced treatment facility. This study proved that the use of LDC was a useful way to achieve TWQ (Target Water Quality) on the target watershed considered. It was also expected that the methodology applied in this study could have a wider application on the establishment of watershed water management measures.

• 한국물환경학회지
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• 제28권3호
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• pp.409-417
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• 2012

SWAT model was applied for the Nakdong River Basin to characterize water quality variability and assess the feasibility of using the load duration curve to water quality management. The basin was divided into 67 sub-basins considering various watershed environment, and rainfall runoff and pollutant loading were simulated based on 6 year measurements of meteo-hydrological data, discharge data of treatment plants, and water quality data (SS, T-N and T-P). The results demonstrate that non-point source loads during wet season increase by 80 ~ 95% of total loads. Although the rate of water flow governs the amount of SS that is transported to the main streams, nutrient concentrations are highly elevated during dry season by being concentrated. This phenomenon is more pronounced in the lower basin, receiving large amounts of urban point source discharges such as treated sewages. Also, the load duration curves (LDC) demonstrate dominant source problems based on the load exceedances, showing that SS concentrations are associated with the rainy season and nutrients, such as T-P, may be more concentrated at low flow and more diluted at higher flow. Overall, the LDC method could be used conveniently to assess watershed characteristics and pollutant loads in watershed scale.

• 한국물환경학회지
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• 제25권5호
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• pp.792-802
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• 2009

The objective of this study is to construct the watershed management system with link of the non-point sources model and to estimate delivery ratio duration curves for various pollutants. For the total water pollution load management system, non-point source model should be performed with the study of the characteristic about non-point sources and loadings of non-point source and the allotment of pollutant in each area. In this study, daily flow rates and delivered pollutant loads of Nakdong river basin are simulated with modified TANK model and minimum variance unbiased estimator and SWAT model. Based on the simulation results, flow duration curves, load duration curves, and delivery ratio duration curves have been established. Then GIS analysis is performed to obtain several hydrological geomorphic characteristics such as watershed area, stream length, watershed slope and runoff curve number. As a result, the SWAT simulation results show good agreements in terms of discharge, BOD, TN, TP but for more exact simulation should be kept studying about variables and parameters which are needed for simulation. And as a result of the characteristic discharges, pollutants loading with the runoff and delivery ratios, non-point sources effects were higher than point sources effects in the small-scale test bed of Nakdong river basin.

• 한국농공학회논문집
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• 제60권6호
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• pp.97-109
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• 2018

The LDC (Load Duration Curve) method can analyze river water quality changes according to flow rate and seasonal conditions. It is also possible to visually recognize whether the target water quality is exceeded or the size of the reduction load. For this reason, it is used for the optimal reduction of TPLCs and analysis of the cause of water pollution. At this time, the flow duration curve should be representative of the water body hydrologic curve, but if not, the uncertainty of the interpretation becomes big because the damaged flow condition is changed. The purpose of this study is to estimate the daily mean flow of the unit watershed using the HSPF model and to analyze the difference of the flow duration curves according to the cumulative daily mean flow rate using the NSE technique. The results show that it is desirable to construct the flow duration curve by using the daily average flow rate of at least 5 years although there is a difference by unit watershed. However, this is the result of the water bodies at the end of Han River basin watershed, so further study on various water bodies will be necessary in the future.

• 환경영향평가
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• 제28권6호
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• pp.536-548
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• 2019

기타 수계 중 삽교천 유역에 새롭게 수립된 오염총량관리제도의 시행에 따른 효과를 정량화하기 위해 2015년을 기준으로 유역유출모형인 HSPF 모형을 구축한 후, 최종 목표연도인 2030년의 부하량을 입력하여 각 단위유역 말단에 설정된 목표수질 달성여부를 평가하였으며, 미시행지역인 무한천과 삽교천 유역을 포함하여 유량구간별 수질(BOD, T-P)을 예측하였다. 보정 및 검증이 완료된 모형에 2030년의 부하량을 입력하여 재구동한 후, 모의결과로부터 부하지속곡선을 작성함으로써 기준년도 부하량을 입력하여 구동한 모의 수질과 목표연도 부하량을 입력하여 모의한 예측 수질을 유량구간별로 도식화한 결과, 평수량 구간(40~60%)에서 3개의 단위유역 모두 BOD 목표수질에 근접하게 모의되었으며, 목표수질 달성율도 높게 산정되었다. T-P의 경우, 천안A 46%, 곡교A 29%, 남원A 25% 정도의 수질이 개선되는 것으로 예측되었으며, 무한천과 삽교천유역은 중권역 목표기준인 III등급 이내의 수질로 모의되었다. 총량관리 대상 단위유역은 목표수질을 달성하고, 미시행지역은 목표등급을 달성하는 수준의 수질이 삽교호 내로 유입될 것으로 예측됨으로써 총량제 시행에 따른 삽교천 유역의 수질개선효과가 긍정적일 것으로 판단된다.

• 한국지리정보학회지
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• 제23권3호
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• pp.174-191
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• 2020

본 연구에서는 대청호 상류에 있는 서화천 유역에서 부하지속곡선을 통한 소유역별 비점오염원 취약지역 및 관리 오염물질과 관리 시기를 분석하였다. 먼저 부하지속곡선을 만들기 위하여 장기 유출 모형인 SWAT를 구축하여 유량지속곡선(Flow Duration Curve)을 작성하였으며 그 결과에 목표 수질을 곱하여 부하지속곡선(Load Duration Curve)을 작성하였다. 목표 수질은 서화천 비점오염원 관리를 위해 지난 2017년 11월부터 측정한 모니터링 자료를 사용하였으며 측정자료의 60분위에 해당하는 값을 목표 수질로 설정하였다. 이때 산정된 값이 하천 생활환경 기준의 "약간좋음"(II)을 초과할 경우 목표 수질을 "약간 좋음"(II)으로 제한하였다. 비점오염원 취약지역은 목표 수질을 초과하는 초과율을 이용하여 선정하였으며 초과 되는 오염물질을 관리 물질로 판단하고 계절별 평가를 통해 관리시기를 선정하였다.