• 한국방재학회:학술대회논문집
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• 2007.02a
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• pp.632-635
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• 2007

Detention pond has an important role in peak flow reduction to mitigate flood damage. Design of detention pond is accomplished through the preliminary stage, planning stage, and design stage in general. New development projects produce increased peak flow and flow amounts. In this case it is necessary to design the detention pond easily and simply. The simple procedure of detention pond design is proposed in this study. The relevant variables are peak flow ratio ($\alpha$) for the before and after development, and storage ratio which is ratio of storage volume to flow amounts. Simplified method for the detention pond design with runoff reduction is easily used for practical purposes.

• Journal of Environmental Science International
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• v.9 no.3
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• pp.193-199
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• 2000

This study is carried out the analysis of the runoff characteristics for the design of the interior drainage systems by SWMM in urbanization basin. The basin analyzed in this study is Bumuh-chun basin which is located in Susung-gu of Taegu city. Huff method is used for rainfall distribution analysis. The optimal rainfall duration in Bumuh-chun basin is analyzed as about 90 minutes decided from comparison of arrival time and critical duration. Flood flow variation pattern is proposed through the comparison of the results of peak flow and peak time analyzed by SWMM about pre-urbanization and post-urbanization of Bumuh-chun basin. It is known that the variation of arrival time caused by the rapid increase of pavement rate in the upper area shows about 20∼25 minutes faster than pre- urbanization. Therefore, the management of surface water for design of water supply and drainage, and channel alteration has to considered the variation of geological factors according to urbanization.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.1798-1802
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• 2007

The practice of business estimate flood discharge by rainfall-flow relation that is easy collection of observation data. The important factor is rainfall, coefficient of runoff, and drainage area for analysis of runoff-flow relation.The practice of business usually use probability rainfall that use a weighted average value after each observation post estimate probability of non-same time. It has more error than same time probability rainfall, and it can excess of estimation because it can't consider space distribution of rainfall.The study of result showed similar aspect with existing ARF but width of coefficient become smaller. And the comparison of peak flow did not different what used by ARF and same time probability rainfall(A group). But non-same time probability rainfall is bigger 25% more than another(B group). Between A group and B group of the difference increased with the lapse of time.

• Journal of Industrial Technology
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• v.27 no.A
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• pp.95-102
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• 2007

The practice of business estimate flood discharge by rainfall-flow relation that is easy collection of observation data. The important factor is rainfall, coefficient of runoff, and drainage area for analysis of runoff-flow relation. The practice of business usually use probability rainfall that use a weighted average value after each observation post estimate probability of non-same time. It has more error than same time probability rainfall, and it can excess of estimation because it can't consider space distribution of rainfall. The study of result showed similar aspect with existing ARF but width of coefficient become smaller. And the comparison of peak flow did not different what used by ARF and same time probability rainfall(A group). But non-same time probability rainfall is bigger 25% more than another(B group). Between A group and B group of the difference increased with the lapse of time.

• Journal of Korea Water Resources Association
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• v.43 no.7
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• pp.635-643
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• 2010

A representative unit hydrograph responding to a small basin is used to calculate the flood discharge in the basin. The peak discharge and the time to peak of the unit hydrograph are dealt with its characteristic values. In this study it is shown and analyzed the fluctuations at peak discharges and times to peak of unit hydrographs by rainfall storms in a small national basin $8.5\;km^2$ wide are no small. And on assumption that a major factor in the fluctuations of the unit hydrographs in a small basin be rainfall intensity of a rainstorm, both relations of peak discharge and time to peak with rainfall intensity are suggested as exponential functions respectively. In this result although it is a limit of the study in which its result is accompanied with not small dispersion in the peak values of unit hydrograph due to a defect in used data it is sure an averaging regression relation between peak discharge and time to peak with rainfall intensity as identified in this study has hydrological worth from the complementary viewpoint of the theory of unit hydrograph.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.8 no.1
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• pp.113-125
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• 1988

The design flood formulas in Korean river are reviewed from the early historical stage of the river improvement projects to the present situation. The 11 different formulas are selected for the comparative purpose of the each results at the same rainfall and basin characteristics under the same size of the basin. The max. and min. values of the design flood discharge for the same basin deviated almost as large as 400% according to the formula used without respect to the basin size. The remains have big scattering within those deviations. The steps to derive the design flood are very complicated and tedious time consuming process at present applications. However the reaults computed through the steps are quationable in accordance with the lengths of the hydrological historic records and the accuracy of the data observation technique in view of the engineering judgement. The purpose of this review will give the one of the simplest and the reasonable approach to eliminate misleading the determination of the design flood peak.

• Water for future
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• v.9 no.2
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• pp.101-114
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• 1976

This paper presents a hydrologic method of probabilistic design flood calculation for ungauged small river basins. It is based on the study and analysis of the physiographic characteristics of the river basin for which stream flow records may not be available. Rainfall data is used at nearby station which has the rainfall intensity-duration-frequency relations. Musim cheon, second tributary of the Guem river, is selected for the sample study. Design floods for the stream reaches are computed by the Rational formula, the runoff coefficients being determined with the physiographic data such as soil type, land use and vepetal covers. Derived unit hydrograph at conneted main river basin is used to compute the peak flood discharge. Kajiyama formula and modified Kajiyama formula are used to calculated the most probable maximum flood discharge. The result of this study shows that synthesized unit hydrograph method is more accurate and applicable way to com pute design flood for ungauged small river basins.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.3
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• pp.957-964
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• 2013

This research is on the methodology of flood risk assessment using flooding characteristic values. Necessity of design magnitude for flood control considering floods was judged by plotting peak flow with respect to frequency and duration, and flooding magnitude was defined with 6 flooding characteristic values which were proposed to be significant factors when assessing flooding magnitude. Precipitation data used in the assessment modeling were applied by combining all the possible precipitation events. After overlapping the simulated results with precipitation matrix by flooding characteristic values, contour map was drawn, and Flooding characteristic contour graph for possible rainfall events were suggested in respect of all possible precipitation. Flooding characteristic contour graph for possible rainfall events was confirmed that reducing of damage magnitude of each flood characteristic value was figured out easily. The flood risk assessment methods suggested in this study would be a good reference for urban drainage system design, which only focuses on pipe conduit.

• Journal of Korea Water Resources Association
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• v.35 no.5
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• pp.553-561
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• 2002

The objectives of this study are to introduce flash flood forecasting system in Korea and to develop a system for computing threshold runoff on very fine catchment scale. The developed GUI system composed of 9 steps starting from input data preparation to Input file creation for flash flood forecasting compute basin subdivision, hydrologic subbasin characteristics, bankfull flows, unit peak flows and threshold runoffs on about 5 $\textrm{km}^2$ scale. When the developed system was applied on Pyungchang IHP basin, the computed 1-hour threshold runoffs ranged 18.72~81.96mm with average value of 46.39mm. Judging from the comparison of the computed threshold runoffs between this study area and three other basins in United States, the computed results in this study were reasonable. It can be concluded that the developed system on ArcView/Avenue are useful for computing threshold runoff on small catchment and can be used as a component of flash flood forecasting system.

• The Journal of Engineering Geology
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• v.25 no.4
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• pp.449-458
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• 2015

The compilation of a flood hazard map is an efficient technique in managing areas at risk of flooding in the case of a dam-break. A scenario-based numerical modeling approach is commonly used to compile a flood hazard map related to dam-break and to determine the model parameters that capture peak discharge, including breach formation and progress, which are important in the modeling method. This approach might be considered less reliable if an existing model is used without local validation. In this study, a dam-break model is linked to a routing model to identify flood-risk areas in the case of failure of the Sandae Reservoir Gyeongju, Gyeongbuk. Model parameters are extracted from a DEM, and maps of land use and soil texture. The simulation results are compared with on-site investigations in terms of inundation and depth. The model reproduces the inundation zone with reasonable accuracy.