• Journal of Korea Water Resources Association
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• v.42 no.10
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• pp.877-889
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• 2009

This study is to assess the future potential impact of climate change on stream water quality for a 6,581.1 km$^2$ dam watershed using SWAT (Soil and Water Assessment Tool) model. The ECHAM5-OM climate data of IPCC (The Intergovernmental Panel on Climate Change) A2, A1B, and B1 emission scenarios were adopted and the future data (2007-2099) were corrected using 30 years (1977-2006, baseline period) weather data and downscaled by Change Factor (CF) method. After model calibration and validation using 6 years (1998-2003) observed daily streamflow and monthly water quality (SS, T-N, and T-P) data, the future (2020s, 2050s and 2080s) hydrological behavior and stream water quality were projected.

• Journal of Environmental Science International
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• v.22 no.6
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• pp.733-744
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• 2013

This study was to investigate characteristics of Seoho watershed in Suwon city. $BOD_5$ and SS were selected due to the one of the important factors of the water qualities. Monitoring was conducted monthly for four years during the non-rainfall time. Also, we have been monitored $BOD_5$, $COD_{Mn}$, SS, TN and TP with two times sampling after the rainfalls. The highest concentrations of $BOD_5$ and SS were observed in downstream compare with upstream and midstream during the non-rainfall time. No change was observed in $BOD_5$ and $COD_{Mn}$ during the non-rainfall time and after the rainfalls. The monitoring result indicated that the concentration of SS was the highest in downstream after the rainfalls. We have collected the samples two times after the rainfalls. The rainfall intensity in first sampling was two times higher than second sampling. TN and TP concentrations were increased with increasing the rainfall intensity at all stream. The ESB (Ecological Score of Benthic macroinverterbrate community) index was used to evaluate the statement of stream. ESB results were identified that the upstream is protected waters and the down and midstream is reformed waters. EBS analysis results indicated that the Seoho watershed was ${\beta}$-mesosaprobic at all stream.

• Journal of Korean Society on Water Environment
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• v.33 no.6
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• pp.650-660
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• 2017

In this study, pollutant emission characteristics by water damage period analyzed 11 items (water temperature, pH, DO, EC, BOD, COD, TOC, SS, T-N, T-P and flow) with load duration curve, time series load curve and factor analysis for three years (2014-2016). Load duration curve is applied to judge the level of impaired waterbody and estimate impaired level by pollutants such as BOD and T-P in this study depending on variation of stream flow. Water quality standard exceeded the flow of mid-range and low-range by flow condition evaluation using load duration curve. This watershed was influenced by point source more than non-point source. Cumulative excess rate of BOD and T-P kept water quality standard for all seasons (spring, summer, autumn and winter) except BOD 59% in spring. Water quality changes were influenced by pollutants of basic environmental treatment facilities and agricultural areas during spring and summer. Results of factor analysis were classified commonly first factor (BOD, COD, and TOC) and second factor (flow, water temperature and SS). Therefore, effects of artificial pollutants and maintenance water must be controlled seasonally and reduced relative to water damage caused by point pollution sources with effluent standard strengthened in the target watershed.

• Journal of Korean Society of Rural Planning
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• v.9 no.2 s.19
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• pp.19-28
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• 2003

It is the purpose of this study to investigate the change of stream water quality in upper stream of Dongjin river, and to give the basic information for the conservation of water quality. Water samples were taken periodically at 9 sampling sites during 8 months from March to October in 2002. The results of this study were as follows : 1. The water temperature and pH of stream water were ranged $9.0{\sim}29.4^{\circ}C,\;6.48{\sim}9.33$, respectively. The COD values of stream water was ranged from 0.60 to 19.06. The contents of T-N and T-P mainly affected by the livestock wastes, and agricultural activity were $1.88{\sim}6.74\;mg/L$, ND(not deleted)${\sim}0.50\;mg/L$, respectively. 2. The SS, DO and BOD values of stream water were ranged $0.4mg/L{\sim}274.0mg/L$, $0.5{\sim}6.0\;mg/L$, and $7.3{\sim}13.7\;mg/L$ respectively. 3. The cation is one of the important components in analysis of stream water quality. The contents of analysis, $Ca^{++},\;Mg^{++},\;Na^+$ and $K^+$ were ranged $1.96{\sim}11.08\;mg/L$, $1.21{\sim}6.16\;mg/L$, $3.38{\sim}18.44\;mg/L$, $1.12{\sim}7.96\;mg/L$, respectively. SAR was ranged $0.31{\sim}1.63$ below 2.0. The contents of cation showed in the order $Na^{++}>Ca^{++}>K^+>Mg^+$. 4. The contents of heavy metal Zn, Cu, and Pb were $ND{\sim}0.071\;mg/L$, $ND{\sim}0.012\;mg/L$, and $ND{\sim}0.043\;mg/L$, respectively. Cd was not detected in all samples. 5. As a result of these researches showed water quality in upper stream watershed of Dongjin river more affected by livestock wastes and living sewage than agricultural activity.

• Journal of Korean Society of Water and Wastewater
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• v.11 no.3
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• pp.112-123
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• 1997

The Anyang stream is one of the Han river in Seoul Metropolitan area. It is 35.1km long, has a basin area of $282.26km^2$ and touches seven cities of Kyounggido and some of Seoul Metropolitan area. The situations of Anyang stream have resulted in severe stream water pollution problems. The purpose of this study were to measure the hydraulic characteristics and water quality, to make the countermeasures to achieve the stream water quality, to suggest the future conditions to improve water quality trough the Hydrodynamic and Water Quality Modal(WASP4). As the result of Anyang stream water quality forecsat, they are follows. Sewerage systems in the watershed of the Anyang stream have to be amended for wrong systemn and constructed in the upstream area of Anyang. The discharge of industrial wastewater has to be throughly controlled from the upstream area of the Anyang stream. Hydrodynamic and Water Quality Model(WASP4) for this study revealed the future water quality of the Anyang stream by computer simulation.

• Journal of Korean Society on Water Environment
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• v.28 no.1
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• pp.18-25
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• 2012

For effective watershed management, it is very important to select the tributaries through selection and concentration of targeted tributary catchments for improving water quality within the limited financial conditions. This study introduced the selection and diagnosis procedure of tributary catchments for improving water quality at Chungcheongnam-do based on water quality and flowrate monitoring, stream grouping method. The tributaries with high value of water quality and flowrate were selected for improving water quality according to stream grouping method. The diagnosis of selected tributaries for improving water quality was performed with analysis of the pollution load (generated, discharged, delivered) and point source discharged pollution load density. The plans for improving water quality of tributaries were suggested thorough various diagnosis of tributary catchments. For improving water quality of tributaries in Chungcheongnam-do, the tributary catchments in the Dangjin, Asan, Yesan, Cheonan, Hongseong area should be preferentially considered. The water quality improving plans for those tributary catchments, in accordance with the reduction of sources of pollution by population and livestock, should be established.

• Journal of Korean Society on Water Environment
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• v.29 no.2
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• pp.212-222
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• 2013

A watershed model was constructed using Hydrological Simulation Program Fortran to quantitatively predict the stream flows at major tributaries of Nakdong River basin, Korea. The entire basin was divided into 32 segments to effectively account for spatial variations in meteorological data and land segment parameter values of each tributary. The model was calibrated at ten tributaries including main stream of the river for a three-year period (2008 to 2010). The deviation values (Dv) of runoff volumes for operational stream flow forecasting for a six month period (2012.1.2 to 2012.6.29) at the ten tributaries ranged from -38.1 to 23.6%, which is on average 7.8% higher than those of runoff volumes for model calibration (-12.5 to 8.2%). The increased prediction errors were mainly from the uncertainties of numerical weather prediction modeling; nevertheless the stream flow forecasting results presented in this study were in a good agreement with the measured data.

• Journal of The Korean Society of Agricultural Engineers
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• v.52 no.5
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• pp.27-35
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• 2010

The characteristics of delivered nutrient loads were analyzed and the regression equations to estimate delivery ratios of nutrients (TN and TP) were developed using HSPF simulation results at six subwatersheds within the Bochung A unit watershed during 1998-2007. TN delivery ratio was higher than TP delivery ratio because significant amounts of TP was considered to be attached at soil as ${PO_4}^-$ during delivery process from discharged point of nutrient source to main stream. As a results of correlation analysis, factors related to geomorphic characteristics had not statistical correlation with TN and TP delivery ratios. TN loading rate from living and specific stream flow had statistical negative and positive correlation, respectively, with TN delivery ratio. TP loading rates from all sources and from land cover and specific stream flow had statistical negative, negative and positive correlation, respectively. The specific stream flow represents the most strong correlation with nutrient delivery ratios. The regression equations to estimate delivery ratios for TN and TP were developed by including statistical correlated factors and showed high efficiency of 0.98 and 0.95 of coefficient of determination for TN and TP, respectively.

• Journal of The Korean Society of Agricultural Engineers
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• v.49 no.6
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• pp.11-20
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• 2007

In order to make the way to determine the instream flow more practically, we have investigated many case studies and reviewed reports and papers. To validate instream flow level suggested by the case studies, DAWAST and HEC-RAS model were applied to the Gap-stream watershed in Daejeon city. Flow-duration analysis was performed both with the stream flow data gauged in the Indong, Boksu, and Hoeduck stations, and with the stream flow data estimated by the DAWAST model and the specific discharge method. Instream flow was determined among the flow-duration analysis, DAWAST, HEC-RAS model and mass balance approach. It was satisfied with various factors such as target water quality, water depth for eco-system and resorts, water surface width, flow velocity for landscape in dry season. The study suggested that the mean low flow could be replaced into the instream flow for the preliminary study because the instream flow considering ecosystem, landscape, water-friendly environment and water quality was generally close to the mean low flow.

• Proceedings of the Korea Water Resources Association Conference
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• 1995.05a
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• pp.283-288
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• 1995