• Journal of The Korean Society of Agricultural Engineers
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• v.55 no.2
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• pp.47-57
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• 2013

This study is to assess the reduction of non-point source pollution loads for rice straw mulching of upland crop cultivation at a watershed scale. For Byulmi-cheon watershed (1.21 $km^2$) located in the upstream of Gyeongan-cheon, the HSPF (Hydrological Simulation Program-Fortran) and SWAT (Soil and Water Assesment Tool), physically based distributed hydrological models were applied. Before evaluation, the model was calibrated and validated using 9 rainfall events. The Nash-Sutcliffe model efficiency (NSE) for streamflow using the HSPF was 0.62~0.76 and the determination coefficient ($R^2$) for water quality (sediment, total nitrogen T-N, and total phosphorus T-P) were 0.72, 0.62, and 0.63 respectively. The NSE for streamflow using the SWAT were 0.43~0.81 and the $R^2$ for water quality (sediment, T-N, and T-P) were 0.54, 0.87, and 0.64 respectively. From the field experiment of 16 rainfall events, the rice straw cover condition reduced surface runoff average 10.0 % compared to normal surface condition. By handling infiltration capacity (INFILT) in HSPF model, the value of 16.0 mm/hr was found to reduce about 10.0 % reduction of surface runoff. For this condition, the reduction effect of sediment, T-N, and T-P loads were 87.2, 28.5, and 85.1 % respectively. By handling soil hydraulic conductivity (SOL_K) in SWAT model, the value of 111.2 mm/hr was found to reduce about 10.0 point reduction of surface runoff. For this condition, the reduction effect of sediment, T-N, and T-P loads were 80.0, 83.2, and 78.7 % respectively. The rice straw surface covering was effective for removing surface runoff dependent loads such as sediment and T-P.

• Journal of The Korean Society of Agricultural Engineers
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• v.47 no.3
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• pp.77-86
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• 2005

A monitoring study has been conducted to identify hydrologic conditions, water quality and nutrient loading characteristics of small watershed in Juam Lake. Climate data of the watershed were collected; flow rate was measured and water quality sampling was conducted at the watershed outlet for this study. Water quality data revealed that T-P concentrations meet I grade of lake water quality standard during non-storm period, but degraded up to II-III grade of lake water quality standard during storm period. The observed T-N concentrations always exceeded lake water quality standard. Therefore, T-P was identified as limiting chemical constituent for eutrophication of Juam Lake. T-P concentration of non-storm period also revealed that point source pollution is not serious in the watershed. Three year monitoring results showed that the observed T-N losses were $10.85\~18.88$ kg/ha and T-P losses were $0.028\~0.323$ kg/ha during six month (Mar. - Oct.), respectively. Major portion of runoff amount discharged by a few storm events a year and nutrient load showed apparent seasonal variation. Huge runoff amounts were generated by intense storms, which make application of water treatment or detention facilities ineffective. Monitoring results confirmed that water quality improvement by abating nonpoint source pollution in rural watershed of monsoon climate should be focused on source control. T-P losses from paddy field seemed to consist of significant amount of total load from study watershed. Therefore, management of drainage from paddy field is considered to be important for preventing algal blooming problem in Juam Lake.

• Journal of Environmental Impact Assessment
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• v.3 no.2
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• pp.47-56
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• 1994

AGNPS model is an event-based model to analyze nonpoint-source and to examine potential water quality problems from agricultural watershed. This model uses a square grid-cell system to represent the spatial variability of watershed conditions, and simulates runoff, sediment, and nutrient transport for each cell. AGNPS model was applied on Yeonwha watershed, and the test results were compared with the measured data for runoff volume, peak runoff rate, suspended solids, and phosphorus concentration. The watershed of 278.8 ha was divided into 278 cells, each of which was 1 ha in size. The coefficients of determination for runoff volume and peak flow were (0.893 and 0.801 respectively from regression of the estimated values on the measured values. The concentration of suspendid solid was increased but decreased that of phosphate with runoff volume.

• Journal of The Korean Society of Agricultural Engineers
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• v.52 no.4
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• pp.19-26
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• 2010

To provide the basic information for the water quality management of the Sumjin River Basin, delivery ratios for flow duration were studied. Using the day-interval data set of discharge and water quality observed from the Chooryeong-cheon watershed, the flow-duration and discharge-load relation curves for the watershed were established, then the load-duration curve was constructed. Delivery ratios for flow duration were also developed. Delivery ratios showed wide variation according to flow conditions. In general, delivery ratio of high flow condition showed higher value reflecting nonpoint source pollution contribution from the forest dominating watershed. To resolve this problem, a regression model explaining the relation between flow rate and delivery ratio was suggested. The delivery ratios for different flow regime could be used for pollutant load estimation and TMDL (Total maximum daily load) development.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2003.10a
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• pp.631-634
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• 2003

A subwatershed within the Lake Juam was monitored to identify hydrologic and water quality characteristics. Rainfall record was collected and flow rate measurement and water quality sampling were conducted periodically at the watershed outlet. Water quality of storm period was worse than that of base flow period. Nutrient loading from the watershed was governed by only a few storms during study period. Nonpoint source pollution was identified major problem for water quality management in Juam Lake.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2003.10a
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• pp.575-578
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• 2003

Constructed wetlands have become a popular technology for treating contaminated surface and wastewater. In this study, the field experiment to reduce nonpoint source pollution from watershed runoff during rainy day using wetland and pond. TSS and T-N removal rate of wetland-pond system and pond-wetland system was 91% and 73%, 94% and 70%, respectively and values were same range. $BOD_5$ and T-P removal rate of pond-wetland system (38% and 78%) was higher than wetland-pond system (27% and 62%). overall, pond-wetland system is more useful than wetland-pond system to control NPS.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1999.10c
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• pp.105-110
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• 1999

Unused irrigation water due to delievery losses and management losses. and ground water releases from infiltration in the paddy irrigation system are eventually returned to the stream. They are called as irrigation return flow. It affects the discharge of drought flow in the down strenamflow. And it may contain chemicals, and threaten streamflow quality . Thus, the accurage estimation of irrigation return flow is important to the streamflow modeling and water resources planning , and also to the control of agriculutral nonpoint source pollution . The irrigation return flow of pumped water was investigated in the Keum river watershed.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.947-951
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• 2010

본 연구는 강우시 A 공업단지와 B 농공단지의 공업지역에서 통계적인 오염물질 농도와 오염물질 특성을 찾아내기 위하여 모니터링 및 분석을 수행하였으며, 강우유출수 조사방법에 따른 원단위 산정을 위하여 유량가중평균농도(EMC)산정, 강우계급별 유량가중평균농도를 산정하였으며, 공업지역의 대표 유량가중평균농도(EMCz) 산정, 유출율을 산정하였으며, 앞에 산정한 자료를 이용하여 선정한 공업지역 원단위를 산정하여 기존 원단위 값과 비교분석 하였다. 이렇게 산출된 자료는 공업지역 비점오염원 최적관리를 위한 과학적 근거자료 제공 및 기초자료서의 활용, 모니터링을 통한 공업지역의 비점오염원의 관리대책 및 낙동강 수질개선을 위한 정책자료에 관한 기초자료 제공, 국내 실정에 부합하는 최적 비점오염원 저감시설의 설치를 위한 기초자료로 활용될 수 있을 것이다.

• Journal of Environmental Impact Assessment
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• v.4 no.2
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• pp.39-57
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• 1995

The water quality model SWAT (Soil and Water Assessment Tool) was used in combination with GIS, Arc/Info and GRASS, to evaluate land use impacts in the Delaware River Basin in Pennsylvania. This paper describes application of GIS with the water quality model in the 250 square kilometer Brodhead Creek Watershed. Date used in water quality modeling include 1:250,000 digital elevation models (DEM), soil data, and monitored streamflow and curve numbers, and other input variables.

• Korean Chemical Engineering Research
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• v.50 no.6
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• pp.980-987
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• 2012

Nonpoint source pollution causes leaks and overtopping, depending on the state of the sewer network as well as aggravates the pollution load of the aqueous water system as it is introduced into the sewer by wash-off. According, the need for efficient sewer monitoring system which can manage the sewage flowrate, water quality, inflow/infiltration and overflow has increased for sewer maintenance and the prevention of environmental pollution. However, the sewer monitoring is not easy since the sewer network is built in underground with the complex nature of its structure and connections. Sewer decontamination mechanism as well as pipe network monitoring and fault diagnosis of water network system on system analysis proposed in this study. First, the pollution removal pattern and behavior of contaminants in the sewer pipe network is analyzed by using sewer process simulation program, stormwater & wastewater management model for expert (XP-SWMM). Second, the sewer network fault diagnosis was performed using the multivariate statistical monitoring to monitor water quality in the sewer and detect the sewer leakage and burst. Sewer decontamination mechanism analysis with static and dynamic state system results showed that loads of total nitrogen (TN) and total phosphorous (TP) during rainfall are greatly increased than non-rainfall, which will aggravate the pollution load of the water system. Accordingly, the sewer outflow in pipe network is analyzed due to the increased flow and inflow of pollutant concentration caused by rainfall. The proposed sewer network monitoring and fault diagnosis technique can be used effectively for the nonpoint source pollution management of the urban watershed as well as continuous monitoring system.