• Applied Biological Chemistry
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• v.39 no.6
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• pp.488-493
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• 1996

As a first step of pesticide runoff studies, runoff losses of captafol were measured under natural rainfall conditions in apple orchard area. The maximum concentration of captafol was 180 ppb at 5 th sampling period when the rainfall occurred within 24 hours after captafol was applied, and the concentration of samples from other periods was below than 20 ppb. Total runoff loss of captafol was below 0.1%. About 10 fold of dilution factor was observed at the merging point with stream near outlet from orchard and about 50 fold was observed at the next merging point which is located further down. Therefore, captafol will not harm the aquatic organisms due to dilution factor$(10{\sim}50\;fold)$ and rapid hydrolytic degradation rate even when it was run off into a stream nearby.

• Water for future
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• v.29 no.3
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• pp.207-216
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• 1996

The subject research attempts to evaluate the variations of total runoff volume, peak flow, and travel time depending on the urbanhization, return periods and rainfall patterns under the situations that the preparation of a large residential site at the lowland areas of the downstream of Dongsu stream in Bupyung-Gu, Incheon city is progressed and the area will be eventually fully developed. The ILLUDAS model was used for the runoff analyses based on 3 differend steps of urbanization and 4 different types of Huff's quantile according to rainfall patterns is Huff's 4 quantile, Huff's 2 quantile, Huff's 3 quantile and Huff's 1 quantile. Under the 80 and 90 % of urbanization to the 70% of urbanization, the mean increasing ratio of total runoff volume for each case is 3.5 and 5.5 %, that of peak flow is 4.2 and 8.8%, and the mean decreasing ratio of travel time is 4.4 and 10.1%, respectively. The mean increasing ratio of total runoff volume according to the return periods is 3.0 and 5.4%, that of peak flow is 3.9 and 8.0% under the same conditions of urbanization.

• Journal of Korea Water Resources Association
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• v.48 no.2
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• pp.105-114
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• 2015

In the case of rapidly developed urban and industrial complex, the most area becomes impervious, which causes the increasing runoff and high probability of flooding. SWMM model has been widely used to calculate stormwater runoff in urban areas, however, the model is limited to interpreting the actual natural phenomenon. It has the uncertainty in the model structure, so it is difficult to calculate the accurate runoff from the urban basin. In this study, the model parameters were investigated and uncertainty was quantified using Uncertainty Quantification Index (UQI). As a result, pipe roughness coefficient has the largest total uncertainty and largest effect on the total runoff. Therefore, when the stormwater pipe network is designed, pipe roughness coefficient has to be calibrated accurately. The quantified uncertainty should be considered in the runoff calculation. It is recommended to understand the characteristics of each parameter for the prevention and mitigation of urban flood.

• Land and Housing Review
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• v.1 no.1
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• pp.75-82
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• 2010

Urban development is a cause of expansion of impervious area. A permanent storage is operated as a method of reducing runoff of watershed. The purpose of study is to propose reasonable choice of simulation model for rainfall-runoff in the prior review system on disaster effect. First, we indicated problem about concentration time choice in the flood simulation. To test the adequacy of a rainfall-runoff simulation model, We analyzed characteristics of rainfall-runoff about urban and natural watersheds. A simulation model was calibrated with the storm of july 7 to July 9 in 2009. From the result, we proposed that SWMM and kinematic wave method as the flood simulation models for urban and natural watersheds. A simulation model and design method of a permanent storage for flood that is proposed in this study will be useful for practical design of flood simulation. The hydrologic analysis method of the study can be used for capacity evaluation of permanent storage plan.

• Journal of Korean Society on Water Environment
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• v.27 no.5
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• pp.580-586
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• 2011

Low impact development (LID) technique is recently proposed as new concept to reduce surface runoff and pollutant loading with various best management practices (BMPs). In this study, LIDMOD2, which is one of the model to evaluate LID, was applied at Mohyeon developing area to evaluate the redcution of annual runoff and pollution loading, cost-reduction efficient by LID with design of structural BMPs including bioretention, wet pond, and wetland. As a simulation results, the bioretention had the highest reduction efficiency for runoff (41.43%), and 22% for T-N and 22% for BOD. Wet pont had the highest reduction efficiency for T-P as showing 25% of reduction rate. As a results of cost-reduction efficient, wet pont represented the highest cost-effective for T-N and BOD with showing 0.43 T-P kg/million won and 17.37 BOD kg/million won, respectively, and bioretention represented the highest cost-effective for T-P with showing 2.52 T-P kg/million won. LID technology could reduce effectively surface runoff and nonpoint source pollution and construct sustainable development. LIDMOD2 could be suggested as useful tool to evaluate and design LID.

• Journal of Korean Society on Water Environment
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• v.27 no.4
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• pp.391-396
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• 2011

Recently it revealed that urban runoff was one of the major source that contaminates the river, lake and estuary because it contains toxic compounds such as heavy metals and Poly Aromatic Hydrocarbons (PAHs) as well as suspended solids, organic compounds and nutrients. The engineered polymetric media in this research were developed for reducing pollutants in urban runoff and would be used to be charged in the storm water treatment equipment. The engineered media that were composed of the polypropylene was foamed to have the buoyancy and then shattered by mechanical for the efficient filtration. In this study, Spherical Expanded Polypropylene Media (SEPM), Crushed Polypropylene Media (CPM), Large Crushed Expanded Polypropylene Media (LCEPM), Small Crushed Expanded Polypropylene Media (SCEPM) were made from polypropylene. Surface characteristics of the developed media were determined by scanning electron microscopy analyses. Also, removal efficiencies of SS, $COD_{Cr}$ in the artificial road runoff and the bed headloss by media and particle pollutants captured by media were examined. Results on the surface characteristics of media indicated that SCEPM had the largest specific surface area, $0.80m^2/g$, the lowest specific gravity, 0.091, and the biggest porosity, 0.63, because of crushing the media at the process of manufacturing. And the SCEPM's removal efficiencies of TSS and $COD_{Cr}$ in the artificial road runoff were 92.9% and 83.6%, respectively and the headloss of SCEPM was the least of them.

• Journal of Korean Society on Water Environment
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• v.39 no.1
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• pp.30-37
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• 2023

This study aimed to evaluate the ability to reduce flood damage caused by abnormal rainfall events due to climate change by utilizing a blue-green roof (BGF), a type of rooftop greening technology. For two buildings with the same roof area, a BGF was installed in the experimental group, a general roof was configured in the control group, and rainfall runoff was compared. A total of 10 rainfall events were tested and analyzed by classifying them into three rainfall classes (less than 10 mm, less than 100 mm, and more than 100 mm). There was a reduction of 100% in the case of 10 mm or less of rainfall, 84. 7% in the case of 100 mm or less, and 39.8% in the case of 100 mm or more. Although this study showed that a BGF was effective in reducing rainfall runoff, additional experiments and analyses of various factors affecting rainfall runoff reduction are needed to generalize the results of the study. This research methodology may be used to develop a method for evaluating the resilience of a BGF to flood damage due to climate change.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1B
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• pp.7-14
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• 2006

The radar relationship was estimated for the selected rainfall event at Yeongchun station within Chungjudam basin where the discharge record was the range of from 1,000 CMS to 9,000 CMS. By calibrating the rainfall coefficient parameter estimated by radar relationship in small hydrology basin, rainfall with the topography properties was calculated. Three different rainfall estimation methods were compared:(1) radar relationship method (2) Thiessen method (3) Isohyetal method (4) Inverse distance method. Basin model was built by applying HEC-GeoHMS which uses digital elevation model to extract hydrological characteristic and generate river network. The proposed basin model was used as an input to HEC-HMS to build a runoff model. The runoff estimation model applying radar data showed the good result. It is proposed that the radar data would produce more rapid and accurate runoff forecasting especially in the case of the partially concentrated rainfall due to the atmospheric change. The proposed radar relationship could efficiently estimate the rainfall on the study area(Chungjudam basin).

• Journal of Soil and Groundwater Environment
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• v.13 no.5
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• pp.20-32
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• 2008

Runoff characteristics of the Oedocheon in Jeju island were investigated using the long-term stream stage monitoring data. At the Cheonah valley in the upstream area and Oedocheon downstream, annual runoff occurred 21 and 12 times, respectively, and their average runoff periods were 21 days and 12 days, respectively. Stream stage response time to rainfall was 4 hours, and storm-water transfer from the upstream, Cheonah valley, to the Oedocheon downstream took about 2 hours. The stream discharge measurements had been carried out from Feb. 2004 to Jul. 2005, and showed that normal discharge of the Oedocheon was 0.39 $m^3$/sec in average. Stage-discharge curves were developed to estimate base flow (normal discharge) and (direct) surface runoff. The base flow separations by a numerical filtering technique illustrated that annual surface runoff and base flow accounted respectively for 31.8${\sim}$36.5%, 63.5${\sim}$68.2% of the total stream discharge.

• Journal of Korean Society of Forest Science
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• v.101 no.2
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• pp.220-225
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• 2012

This study was carried out to clarify the impact of land use (Castanea crenata, Pinus densiflora and Plantation Land) on soil runoff in small watershed. The soil runoff showed in order of plantation land, Castanea stand and Pinus stand. The resulting models in linear equations of three stands were able to account for 70%, 60% and 60% respectively. The relationship between soil runoff and forest environmental factors was a positive correlation at 1% level with slope, forest type, soil hardness, watershed area, stream length and at 5% level with accumulative rainfall, but was negative correlation at 1% level with coverage. The main factors that affected soil runoff in small watershed showed in order of coverage, accumulative rainfall and stand type. In the stepwise regression between soil runoff and forest environmental factors, the estimation equation is as follow; Y = 31.250 - 1.140(Coverage) + 0.413(Accumulative rainfall) + 20.829(Forest type). The results indicates that dangerous areas of landslide and soil runoff by land use could be applied to the mitigation measures such as afforestation, erosion check dam and revetment for erosion control and water quality management in small watershed.