• 한국농공학회지
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• 제45권2호
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• pp.116-125
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• 2003

Predictions of stream water quality require both estimation of pollutant loading from different sources and simulation of water quality processes in the stream. Nonpoint source pollution models are often employed for estimating pollutant loading in rural watersheds. In this study, a conjunctive application of SWAT model and WASP model was made and evaluated for its applicability based on the simulation results. Runoff and nutrient loading obtained from the SWAT model were used for generating input data for WASP model. The results showed that the simulated runoff was in good agreement with the observed data and indicated reasonable applicability. Loading for the water quality parameters predicted by WASP model also showed a reasonable agreement with the observed data. It is expected that stream water quality could be predicted by the coupled application of the two models, SWAT and WASP, in rural watersheds.

• 한국습지학회지
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• 제25권2호
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• pp.99-110
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• 2023

농업지역에서 발생하는 비점오염물질은 타 지역에 비해 넓은 면적에서 배출되기 때문에 수질관리를 위해서는 발생원 제어와 배출수 관리와 같은 다양한 오염원 저감대책이 필요하며, 이를 위해서는 유역특성을 고려한 오염원별 배출량 및 최적관리방안에 따른 수질개선 효과를 정량적으로 파악할 필요가 있다. 이에 본 연구는 Hydrological Simulation Program-FORTRAN(HSPF)모델을 활용하여 유역내 오염원별 부하 및 주요 오염원저감방안에 대한 수질개선효과를 분석하여 농업지역의 비점오염관리대책 수립 지원을 목적으로 하였다. 연구지역은 경남 창녕군 계성천 유역으로 전체 면적대비 농업지역이 약 26.13%로 산림을 제외하고 지배적인 토지이용을 가지며, 주요 오염원은 농업활동에 기인하는 화학비료 및 액비살포와 축사에서 발생하여 야적 또는 농지에 살포되는 축분을 포함하고 있다. 계성천 유역에 대한 HSPF 모델 구축시 화학비료와 액비 사용량, 소규모 축사의 축분 발생량과 공공하수처리장, 분뇨처리장, 마을하수도 및 개인오수처리시설 등 점오염원 영향을 고려하였다. 특히 본 연구에서는 영양염류의 식생흡수, 침적, 흡탈착, 깊은침투에 의한 손실 등 상세 순환기작모의가 가능하도록 NITR 및 PHOS모듈을 활용하였다. 구축된 모델은 유역말단의 2015~2020년 측정값을 토대로 보·검정을 수행하였으며 모델이 유량 및 수질을 적절히 모의하는 것을 확인하였다. 오염저감시나리오는 농업비점관리(배수물꼬관리, 완효성비료와 사용), 축산비점관리(액비저감, 소규모 축사 축분관리), 생활계오염원제어(개인오수처리시설 관리) 등 세 부문으로 구분하고, 달성기간에 따라 단기, 중기, 및 장기로 구분하여 부문별로 단계별 저감대책을 구성하였다. 개별시나리오 모의 결과 수질개선에 효과는 완효성비료의 대체사용>배수물꼬관리>소규모축사 축분관리 순으로 나타났다. 유역 전반에 모든 관리방안을 적용하였을 때 장기적으로 TN, TP의 연간부하량은 각각 40.6%, 41.1%, 연평균 농도는 각각 35.1%, 29.2% 감소되는 효과를 보였다. 본 연구를 통하여 농업활동 우세 유역에서의 다양한 오염원 저감시나리오별 수질개선효과에 대한 예측 및 이에 기반한 오염관리대책 우선순위 도출을 위한 합리적인 방법론을 제시하고자 한다.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2002년도 학술발표회 발표논문집
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• pp.381-384
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• 2002

The purpose of this study is to construct an Environment Database Management System (EDMS) for the Saemangeum watershed based on the linkage of Water Quality Model, i.e. QUALKO and WASP model, and GIS database to estimate water quality effectively in this area. There are two major river systems on this study area, the Mangyeong and the Dongjin rivers. Input data are automatically generated through the calculation of the pollutant loading and inflow concentration from the point and non-point sources. The developed system is composed of three different phases, such as pre-process, model performance and post-process. The Model performance is supported by the database at pre-process phase and model performance results were shown in the graphs and attribution data at post-process phase. The measured data from the Mangyeong and the Dongjin rivers are used to evaluate the applicability of EDMS. The EDMS shows higher reliability, and it is expected to contribute to the effective management and improvement of water quality modeling in the Saemangeum watershed since the system reduces complications of using a model in DOS operating environment and increases the accuracy of water quality analysis.

• 한국물환경학회지
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• 제38권6호
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• pp.316-326
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• 2022

This study aimed to investigate the causes of the increasing Total Phosphate(TP) in the mainstream of Mangyeong river over the past 10 years, and suggested a reduction plan of about 3 points. First, the high TP concentration was continuously released in the discharge outlet of the Haepo bridge stormwater pipeline. The average TP concentration was 5.066 mg/L and values as high as 29.470 mg/L were measured. The highest pollution contribution rate to the Mangyeong river was more than 70 %. The cause of the pollution was expected to take place somewhere in Wanju Industrial Complex. Second, the average TP concentration of wastewater-treated effluent in the H factory was 0.405 mg/L. If a TP reduction facility is additionally installed in the H factory, it will help reduce TP uptake by Lake Saemangeum. Third, the TP concentration of untreated non-point source point flowing into the Samrae stream was very high with an average of 2.828 mg/L. Also, the pollution contribution rate of Samraecheon 2 to Mangyeong river was 21.8 % on average and up to 58 %. The pollution contribution rate was also high during the agricultural season and the winter, during which the flow rate is decreased. Investigation of these three points may be continuously needed, and analysis results and policy proposals presented to Jeollabukdo and Wanjugun to manage pollution sources.

• 한국환경농학회지
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• 제27권1호
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• pp.10-17
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• 2008

The objective of this study was to estimate the pollutant loads from paddy fields by cultivation practices using a non-point-sources models. One of them is CREAMS-PADDY model that was developed considering the water balance and mass balance of paddy fields. The CREAMS-PADDY model was applied to provide basic data to reduce runoff loadings under various scenarios such as various water management control and various fertilizer condition. The model was verified against T-N, T-P and runoff flow data collected during cropping periods at 2000. The model results agreed well with the measured data in verification. The results showed that the model could be used for estimating the runoff loadings from irrigated paddy fields by cultivation practices was possible. Comparison of simulated the standard height and the sluice management of T-N and T-P runoff loadings from paddy fields were +32.4%, +10.3% in 10 mm below the standard height, -29.2%, -35.9% in 20 mm above the standard height, 52.6%, 59.0% in 40 mm above the standard height, respectively. Comparison of simulated the standard fertilizer and the fertilizer control of T-N and T-P runoff loadings from paddy fields were -1.3%, -21.7%in reduction of conventional fertilizer 30%, -1.0%, -12.5% in reduction of standard fertilizer 30%, respectively. Therefore, reducing nonpoint-sources nutrient loading by reducing fertilization may not work well in the range of normal paddy rice farming practices, and instead it could be achieved by reducing surface drainage outflow.

• 한국농공학회논문집
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• 제61권3호
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• pp.15-22
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• 2019

In order to preserve water environment, Total Maximum Daily Load(TMDL) is used to manage the total amount of pollutant from various sources, and the annual average load of source is calculated by the unit load method. Determination of the unit load requires reliable data accumulation and analysis based on a reasonable estimation method. In this study, we propose a revised unit load estimation method by analyzing the unit load calculation procedure of National Institute of Environment Research(NIER) method. Both methods were tested using observed runoff ratio and water quality data of rice paddy fields. The estimated values with the respective NIER and revised NIER methods were highly correlated each other. However, the Event Mean Concentration(EMC) and the runoff ratio considered in the NIER method appeared to be influenced by rainfall classes, and the difference in unit load increases as the runoff and EMC increase. The error can be further increased when the EMC and runoff ratio are changed according to changes in rainfall patterns by climate change and change of agricultural activities. Therefore, it is recommended to calculate unit load by applying the revised NIER method reflecting the non point pollution runoff characteristics for different rainfall classes.

• 환경영향평가
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• 제17권3호
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• pp.189-200
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• 2008

As a transition zone between terrestrial and aquatic ecosystems, riparian areas of rivers and streams play significant roles in production and decomposition for river and stream systems. Understanding of the physical and ecological characteristics of riparian areas are, therefore, important for the management of river and stream systems. It is especially important to understand the characteristics of riparian areas for the Nakdong River in Korea which has a large watershed area and diverse land uses. This study aimed at collecting field data, according to stream types, which are essential for the management of riparian areas of the middle and lower reaches of the Nakdong River, Korea. Most riparian areas surveyed in this study had roads within 100 meters from river edges. Distances from water edge to banks were less than 1m for most riparian areas neighboring agricultural lands, indicating that those areas might be very vulnerable to pollutant inputs from non-point sources. Water quality data indicated that soil erosion in the riparian areas could be a major source of phosphorus input to the Nakdong River and land use patters might have a significant influence on nitrogen concentration in the river. Heavy metal concentrations in soils of the riparian areas of the river were below soil quality standards, except arsenic and chromium. Vegetation surveys showed that therophytes were the most frequently occurred riparian plants in the Nakdong River. Number of aquatic plant species increased downstream, with the most diverse aquatic plants observed in wetlands and irrigation canals of the West Nakdong River. Occurrence rate of naturalized plants and urbanization index were high in the survey sites adjacent to urban and agricultural areas.

• 한국농공학회논문집
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• 제48권6호
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• pp.89-100
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• 2006

In order to estimate delivered nutrients load from non-point sources in the Gap stream watershed in Daejeon, a distributed watershed model SWAT2000 was used so that it could predict the impact of land management practices on water, sediments and chemicals yields in large complex watersheds with varing soils, land uses and management condition over long period of time. The SWAT2000 was applied to the Daejeon (Indong), Yudeung (Boksu) and Gap (Hoeduck) streams for TMDL (Total Maximum Daily Load) of nutrients. The observed water quality and streamflow data of the year of 2002 and 2003 were used for calibration, and those of the year 2004 and 2005 were used for validation. Simulated results were evaluated by Estimation Efficiency Analysis (COE), Regression Analysis $(R^2)$ and Relative Error (R.E.) for the nutrients amounts on the monthly and yearly basis by comparing observed load with estimated load obtained by using SWAT2000 simulations. The COE value fur T-N was ranged from 0.59 to 0.78, $R^2$ values for T-N ranged from 0.65 to 0.84, and R.E values fur T-N load ranged from 4% to 20%. COE value far T-N was ranged from 0.59 to 0.73, $R^2$ values for T-P ranged from 0.67 to 0.82, and R.E values for T-P load ranged from 3% to 25%. Estimated results of SWAT2000 simulation for 3 sites (Indong, Boksu, Hoedeok) were reasonably satisfactory. This study indicated that SWAT2000 model could be applicable to estimate the nutrients load from the Gap stream watershed in Korea.

• 한국농공학회논문집
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• 제62권5호
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• pp.15-26
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• 2020

There are fifteen non-point pollution management areas in Korea and three of them (Doam lake, Daegi district and Golji-cheon) are located in the upstream of the Namhan river watershed. Many efforts to reduce non-point sources (NPS) pollution have been conducted, however, water quality pollution in the watershed is still serious. To solve these problems, it is a priority to grasp water quality using statistical techniques. In this study, a trend analysis was conducted to evaluate the effect of NPS management in the watershed. The long-term trends from 1996 to 2018 of water quality properties were analyzed using data collected from the water environment information system. Seventeen monitoring stations were selected along the main stream in Namhan river basin. Monthly water quality properties (BOD, COD, TN, TP, TN/TP ratio, Conductivity, SS and Chlorophyll-a) were collected and analyzed by Mann-Kendall test and LOWESS. The results showed that the Conductivity tended to increase in all regions and was the highest level in Jijangcheon. Organic pollution such as BOD and COD tended to increase in the Jungseon area. SS did not show a large tendency, but it showed high concentration in the Doam watershed. In all regions, 40% of water quality properties showed a tendency to 'UP', 15% of water quality properties tended to 'DOWN', and 46% indicated no tendency. In order to determine the cause of this, additional research and measures for improvement are necessary. This study will be used for the establishment of water quality policy in the future.

• 한국농공학회논문집
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• 제64권1호
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• pp.65-77
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• 2022

Due to muddy water from the highland fields upstream of Soyangho Lake, the Mandae, Gaa, and Jawoon have been redesignated as NPS management areas. This study aims to evaluate the adequacy and supplementation points of the implementation plan by analyzing the operation status of muddy water generation and reduction facilities through on-site investigations by NPS management area to achieve the effective nonpoint pollution reduction goal in the implementation of the implementation plan established in 2020. The SS load calculated based on the survey results from July to October 2019 from 2017 showed a decreasen in 2019 compared to 2017. Both and the Jawoon were analyzed to have decreased. However, the amount of precipitation also decreased by about 27%, so it was judged that the effect of the reduction project was not significant. As a result of the detailed investigation of abatement facilities, about 86% of the 793 facilities installed in the management area were evaluated as 'good'. As a result of a detailed investigation by subwatersheds, subwatersheds 105 and 106 in the Mandae were analyzed as apprehensive subwatersheds. appeared to fall. In addition, it was analyzed that the effect of reducing muddy water in the Mandae district was insufficient due to the high ratio of leased farmers, lack of efforts to reduce turbid water in leased farmland, conversion to annual crops, and neglect of bare land. In the case of Gaa district, although the abatement facilities are concentrated in the upstream, muddy water was also found to be severe.