• Journal of the Korean GEO-environmental Society
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• v.24 no.12
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• pp.31-38
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• 2023

In this study, runoff characteristics analysis was conducted as a basic research to establish a forecasting and warning system for flood risk areas in small mountainous basins in South Korea. The Danyang 1 Bridge basin located in Danyang-gun, Chungcheongbuk-do was selected as the study basin, and the watershed characteristic factors were calculated using Q-GIS based on the digital elevation model (DEM) of the basin. In addition, nine heavy rainfall events were selected from 2020 to 2023 using hydrometeorological data provided by the National Water Resources Management Comprehensive Information System. HEC-HMS rainfall-runoff model was used to analyze the runoff characteristics of small mountainous basins, and rainfall-runoff model simulation was performed by reflecting 9 heavy rainfall events and calculated basin characteristic factors. Based on the rainfall-runoff model, parameter optimization was performed for six heavy rain events with large error rates among the simulated events, and the appropriate parameter range for the Danyang 1 Bridge basin, a small mountainous basin, was calculated to be 0.8 to 3.4. The results of this study will be utilized as foundational data for establishing flood forecasting and warning systems in small mountainous basin, and further research will be conducted to derive the range of parameters according to basin characteristics.

• Journal of Environmental Impact Assessment
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• v.15 no.2
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• pp.157-163
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• 2006

The purpose of this study is to understand imperviousness impact for the characteristics of stormwater runoff and water temperature. The land-use map was used to estimate the watershed imperviousness(percent of impermeable area) and the RMS(Remote Monitoring System) was used to evaluate the stormwater runoff of watershed. This study was investigated for two streams(Jiam and Gongji) in Chunchon City. The detailed results of these studies are as follows; The imperviousness(%) of two watersheds(Jiam and Gongji) estimated by spatial analysis which is main function of GIS were 0.24% and 24.16%. So, Gongji watershed as urban area was about 100 times than jiam watershed as forest area. In case of rainfall of low intensity, stormwater runoff flowrate in higher imperviousness area(Gongji) was more than it in forest area(jiam). Also, The time to peak flowrate(Tp) was short in Gongji stream and the water temperature difference between Gongji and Jiam stream was about $4.4^{\circ}C$ in summer.

• Journal of Environmental Science International
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• v.19 no.11
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• pp.1375-1384
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• 2010

Growth in population and urbanization has progressively increased the loading of pollutants from nonpoint sources as well as point sources. Especially in case of road regions such as city trunk road, national road and highway are rainfall and pollutants runoff intensive landuses since they are impervious and emit a lot of pollutants from vehicle activity. This research was conducted to investigate the nonpoint sources concentration and quantifying stormwater pollutants which are contained in rainfall runoff water. Three different monitoring sites in Jinju and Changwon city were equipped with an automatic rainfall gauge and flow meter for measuring rainfall and the volume of rainfall runoff. In the case of average EMC value, city trunk road was shown the highest value in target water quality items like as BOD, COD, SS, TN and TP. Or the amount of runoff loads by water quality items showed the highest value in city trunk road. And runoff load in city trunk road was 43.8 times high value compared to highway by value of city trunk road $356.7 mg/m^2$, highway $8.150 mg/m^2$, national road $19.99 mg/m^2$ in the case of BOD.

• Journal of Environmental Science International
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• v.20 no.3
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• pp.361-372
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• 2011

This study analyzed the characteristics of stormwater runoff by rainfall type in orchard areas for two years. Effluents were monitored to calculate the EMCs and runoff loads of each pollutant. The runoff characteristics for nonpoint sources from vineyards were also inspected based on independent variables that affect runoff such as rainfall and rainfall intensity. The average runoff loads of each pollutant from vineyard_A and vineyard_B were found as follows: BOD 39.13 mg/$m^2$, COD 112.13 mg/$m^2$, TOC 54.98 mg/$m^2$, SS 1,681.8 mg/$m^2$, TN 18.29 mg/$m^2$, and TP 4.06 mg/$m^2$, which indicates that the COD's runoff load was especially high. The average EMCs from vineyard_A and vineyard_B, which represents the quality of rainfall effluent, were also analyzed: BOD 3.5 mg/L, COD 11.5 mg/L, TOC 5.2 mg/L, SS 211.7 mg/L, TN 1.774 mg/L, and TP 0.324 mg/L. This suggested that the COD, as an indicator of organic pollutants, is high in terms of EMCs as well. As rainfall increased, the EMCs of BOD, COD, TOC and SS kept turning upward. At a point, however, the high rainfall brought about dilution effects and began to push down the EMCs. Higher rainfall intensities led to the increase in the EMCs that displays the convergence of rainfall. Low rainfall intensities also raised pollutant concentrations, although the concentrations themselves were slightly different among pollutants.

• Journal of Korea Water Resources Association
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• v.39 no.11 s.172
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• pp.905-914
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• 2006

For an accurate rainfall-runoff simulation in the river basin, not evaluation of runoff model but accurate runoff data are very important. In this study, SSARR model was applied to the Geum River basin and these results are compared with runoff data observed at the Gongju gauging station. The model results didn't good fit the discharge data determined from the rating curve at Gongju gauging station during normal and dry season, especially. For the reliability analysis for the existing rating curve, we observed new stream discharge set from 2003 to 2005. We also estimated long term runoff data from the base flow separation method and defined the hydraulic characteristics. The results show that the new observed stream discharge is similar to the rainfall-runoff model results but existing rating curve seems to be overestimated about 10-20% during normal and dry season. We found that the continuous monitoring and update for the existing rating curve at the gaging station are needed for accurate estimation of runoff data.

• Magazine of the Korean Society of Agricultural Engineers
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• v.16 no.2
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• pp.3438-3453
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• 1974

Unmeasured value of water for human lives is widely approved, but the water as one of natural resources cannot be evaluated with ease since it changes itself ceaselessly by flowing-out or transforming the phase. Major objectives of the study concerned consequently with investigating its potentiality and evaluating its time seriesly availabity in a volumatic unit. And the study was performed to give the accurate original data to the planners concerned. Some developed rational methods of predicting runoff related to hydrological factors as precipitation, were to be discusseed for their theorical background and to be introduced whether they needed some corrections or not, comparing their estimation with actual runoff from synthetic unit-hydrograph methods. To do so, the study was performed to select Kongju Station, located at the watershed of the Keum River, and to collect such hydrological data from 1962 to 1972 as runoff, water level, precipitation, and so on. On the other hand, the hydrological characteristics of runoff were concluded more reasonably in numerical values, with calculating the the ratio of daily runoff to annual discharge of the flow in percentage, as. the distribution ratio of runoff. The results of the study can be summarized as follows; (1) There needed some consideration to apply the Kajiyama's Formula for predicting monthly runoff of rivers in Korea.(2) The rational methods of predicting runoff might be recommended to become less theorical and reliable than the unique analyzation of data concerned in each given water basin. The results from the Keum River prepared above would be available to any programms concerned. (3) The most accurate estimation for runoff could be suggested to synthetic unithydrograph methods calculated from the relation between each storm and runoff. However it was not contained in the study. (4) The relations between rainfall and runoff at KongJu Station were as following table. The table showed some intersting implications about the characteristics of runoff at site, which indicated that the runoff during three months from July to September approached total of 60% of quantity while precipitation concentrated on the other three from June to August. And there were some months which had more amount of runoff than expected values calculated from the precipitation, such as Febrary, March, August, September, Octover, and December, shown in the table. Such implications should be suggested to meet any correction factors in the future formulation concerned with the subjects, if any rational methods would be required.

• Journal of the Korean Society of Hazard Mitigation
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• v.4 no.4 s.15
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• pp.27-34
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• 2004

In this paper, in order to analyse the variation of runoff characteristics depending upon installation of the groundwater recharge facilities, the experiment basin was prepared and the ratio of infiltration and runoff volume were observed in the rainfall events. For the rainfall analysis, 4 types of rainfall events were examined during July 11${\sim}$July 17, 2004. The results show that the mean ratio of infiltration was 89.39% and the mean ratio of runoff was 10.61%. For the artificial rainfall events, which are in the range of rainfall intensities between 60mm/hr and 100mm/hr, all the rainfall volume was infiltrated through the groundwater recharging basin. However, it is necessary to be careful for the long term rainfall, the runoff can be occurred based on the groundwater table.

• Journal of Korean Society of Water and Wastewater
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• v.25 no.2
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• pp.265-274
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• 2011

Nowadays, the importance of non-point source pollution treatment is being emphasized. Especially, the easy runoff characteristic of highly concentrated pollutants in the roads makes the circumstance more complicated due to impermeability of roads. When the pollutants flow into steam it could make water quality in stream worse and it also causes a bad influence in the aquatic ecosystem because the effluents of rainfall-runoff may contain indecomposable materials like oil and heavy metals. Therefore, we tried to figure out the property of non-point source pollution when it is raining and carried out an assessment for the property of runoff for non-point source pollution and EMC (Event Mean Concentrations) of the essential pollutants during this study. As the result of the study, the EMC was BOD 5.2~21.7 mg/L, COD 7.5~35.4 mg/L, TSS 71.5~466.1 mg/L, T-N 0.682~1.789 mg/L and T-P 0.174~0.378 mg/L, respectively. The decreasing rate of non-point pollutant in Chungyang-Hongsung road indicates the maximum decrease of 80% until 5 mm of rainfall based on SS concentration; by the rainy time within 20~30 minutes, the decreasing rate of SS concentration was shown as 88.0~97.6%. Therefore it was concluded that it seems to be possibly control non-point pollutants if we install equipments to treat non-point pollutants with holding capacity of 30 min. It is supposed that the result of this study could be used for non-point pollutants treatment of roads in Chungyang-Hongsung area. We also want to systematically study and consistently prepare the efficient management of runoff from non-point source pollution and pollutant loading because the characteristics of non-point source pollution runoff changes depending on different characteristics and situations of roads and rainfall.

• Journal of Korea Water Resources Association
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• v.38 no.2
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• pp.167-177
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• 2005

In this study, the PRMS(Precipitation and Runoff Modeling System), developed by USGS(United States Geological Survey), was applied to the Yongdam dam watershed in the Geum River basin. The efficiency for runoff simulation and spatial characteristics of PRMS were evaluated. The runoff changes with the changes of subcatchments and HRUs were estimated. As results, the size of the subcatchment and HRV did not significantly affect the runoff at the exit of watershed. Consequently, the spatial characteristic of PRMS was shown as lumped type rather than semi-distributed. The geographical input data for Yongdam dam watershed were converted to the USGS Input type, and the parameters were calibrated using Rosenbrock optimization method, validated with the observed runoff data. The PRMS showed resonable agreements in the long-term continuous runoff simulation, if the accuracy of observed data is ensured.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.1
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• pp.97-102
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• 2008

The Natural Resource Conservation Service Curve Number(NRCS-CN) method is one of the widely used methods for computation of runoff from a basin. However, NRCS-CN method has a weak point in that the spatial land use distribution characteristics are ignored by using area-weighted CN value. This study developed a runoff estimation algorithm which can reflect the spatial land-use distribution. The algorithm consists of Moglen's theory and a developed flow accumulation estimation program in FORTRAN. Comparisons between the results from area-weighted CN method and this study showed reasonably good agreement with measured data of experimental watersheds. The developed program predicted lower runoff than the conventional NRCS-CN method. As a conclusion, this study proposes a new design direction which can simulate real runoff phenomena. And the developed program could be applied into runoff minimization design for a basin development.