• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.811-815
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• 2005

산악지역의 유출은 지형적 특성 때문에 매우 빠른 반응시간을 가지고 첨두유량 또한 매우 크게 마련인데 이러한 특성 때문에 산악지역의 돌발홍수 발생 메카니즘과 이것의 정확한 규명은 지금까지 수많은 연구과제의 주제가 되어왔다. 본 연구는 산악지역의 유출 특성을 잘 반영한다고 알려진 수문지형학을 기초한 지형기후학적단위도(geomorphoclimatic unit hydrograph, GCUH) 이론을 토대로 단일유역 산악지역과 분할유역 규모의 유출 특성을 규명하고 각각의 유역특성에 맞는 돌발홍수예경보시스템을 제안 및 비교 검토하고자 한다.

• Water for future
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• v.20 no.4
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• pp.285-294
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• 1987

The floodwave analysis for unsteady supercritical flow is performed. The numerical model. based on dynamic wave equation is presented by introducing the general Preissmann scheme and fore-sweep algorithm.The model is applied to Buffalo-Creek floods for proving its validity, and the simulation results have good agreements with those computed by DAMBRK and the observed data. It is also applied to Hyogi dam-break. The outflow hydrograph is derived based on the observed data and the analysis for the floodwave propagation is investigated.

• Water for future
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• v.23 no.4
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• pp.421-434
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• 1990

The problems of hydrologic similarity among river basins was analyzed by a geomorphologic response model using Hortons*s ordering scheme. The Nash model was used for deriving the geomorphologic response function, and for the optimization of the responsefunction, imcomplete gamma function andRosso*s regression equation were used. The application of this method was tested on some observed flood data of Pyungchang river basin and Wi Stream basin and Bocheong stream, and predictions of hydrologic response were compared with that of the Moment method. The results show that the proposed model and dimensionless instantaneous unit hydrograph can be used for the runoff analysis of an ungauged basin and the analysis of hydrologic similarity.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.949-949
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• 2012

유출수문곡선은 강우량, 강우강도, 강우지속시간, 강우이동방향 및 이동속도와 같은 강우발생특성과 강수대의 공간적 이류방향과 유역형상과의 상호작용에 의하여 영향을 받으며, 특히 강우의 이류과정에서 나타나는 시간적, 공간적인 분포는 유출에 영향을 미치는 중요한 인자이다. 일반적으로 유출해석 기본이론은 연속방정식과 운동방정식으로서 운동파가정(kinematic wave analogy)을 기반으로 한 집중수문모형(lumped hydrologic model)에 의하여 수행되고 있지만 집중형 모형은 한 매개변수에 여러 가지의 물리적 과정을 개념화하여 담고 있기 때문에 유출과정에 대한 섬세한 모형화의 제약으로 인하여 강우의 이류과정에 따른 유출변화특성을 모의하기가 어렵다. 본 연구에서는 완전 분포형 수문동력학적 강우-유출 모형을 사용하여 강우의 이류특성을 반영할 수 있는 유출 모델을 구성하고, 강우의 이류특성에 따른 유역 출구에서의 유출수문곡선의 변화과정을 살펴보고 상관관계를 분석하였다.

• Journal of Korea Water Resources Association
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• v.49 no.6
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• pp.459-467
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• 2016

LISFLOOD-FP model in which channel flows are resolved separately from the floodplain flows using either a kinematic or diffusive wave approximation has been used to analyze flooding behavior on the lower Mankyung River influenced by backwater. A calibration and validation process was applied using the previous flood events to assess the model performance. Sensitivity analysis was conducted for main calibrated parameters, such as Manning roughness coefficient and downstream boundary condition. Also, we examined the effect of warm-up for the initial conditions. The results show that the computed hydrograph is in good agreement with measured data on the study reach, even though it was a hydrologic kinematic wave model. The sensitive analysis show that the difference between the computed results may be greater depending on the used calibrated parameters and that the sufficient calibration/validation process against various flood events is necessary. If the flood inundation simulation is performed using the validated model, it is expected to be able to contribute about river planning and policy decision-making for flood damage reduction.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.1
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• pp.495-505
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• 2014

The retention basin is a river-facility for the flood mitigation by storing the river flow temporarily. The new 3 retention basins are installed in these regions YeoJu, NaJu, YoungWol by the Large River Management Project. In this study, 1D and 2D numerical flow simulation are conducted to evaluate the reduction effect of the peak flood stage for the YeoJu retention basin. HEC-RAS and FLDWAV models are used for 1D simulation with the option of retention basin. CCHE2D model is used for 2D simulation with the same hydrograph used in 1D simulation. It is verified that the peak flood stage is reduced very largely about 0.13 m near the overtopping section of the levee in 1D simulation. It is verified that the peak flood stage is reduced very largely about 0.20 m at the upstream-end of the simulated reach in 2D simulation. 2D simulation for the retention basin is more reasonable because physical characteristics of topography in the model, and also more advantageous for the evaluation of the flow characteristics of the in- and outside of the retention basin on the results of simulation of this study.

• Journal of Korea Water Resources Association
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• v.42 no.4
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• pp.319-329
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• 2009

Sediment release openings or pipes are installed in the flood control dam constructed to reduce flood damages, which are to allow water and sediments pass through the dam and to prevent flow blockage and sedimentation in the upstream area of the dam. The Hantan River Flood Control Dam (HRFCD) has been projected for flood damage reduction and sediment release openings and ecological passages are considered for the dam design. In this study, sediment deposition due to the construction of HRFCD was analyzed using the HEC-6 model and compared with the state before the dam construction with respect to the conditions of the annual mean daily discharge and annual discharge hydrograph. According to the numerical results, although downstream water levels were changed by the dam structure, the effects of bed changes were not propagated from the dam over 2 km upstream. Also, 2D numerical models of RMA2 and SED2D were used to predict bed changes in the upstream area with and without sediment release openings. Consequently, it is presented that sediment release openings decreased maximum deposition height in the upstream channel of the dam.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.2
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• pp.231-243
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• 2016

This study presents the applicability of two-dimensional (2D) flood inundation model by applying to real irrigation reservoir failure with limited available data. The study area is Sandae Reservoir placed in Gyeongju and downstream area of it and the reservoir was failured by piping in 2013. The breach hydrograph was estimated from one-dimensional (1D) hydrodynamic model and the discharge was employed for upstream boundary of 2D flood inundation model. Topography of study area was generated by integrating digital contour map and satellite data, and Cartesian grids with 3m resolution to consider geometry of building, road and public stadium were used for 2D flood inundation analysis. The model validation was carried out by comparing predictions with field survey data including reservoir breach outflow, flood extent, flood height and arrival time, and identifying rational ranges with allowed error. In addition, the applicability of 2D model is examined using different simulation conditions involving grid size, building and roughness coefficient. This study is expected to contributed to analysis of irrigation reservoirs were at risk of a failure and setting up Emergency Action Plan (EAP) against irrigation reservoir failure.

• Current Research on Agriculture and Life Sciences
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• v.16
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• pp.37-44
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• 1998

The estimation of PMP (Probable Maximum Precipitation) and the analysis of characteristics of PMF (Probable Maximum Flood) according to the types of time distribution of rainfall and variations of base flow for the determination of design flood of major hydraulic structures in the watershed area of Wi stream were analysed. The PMP was estimated by the hydro-meteorological method suggested by the guideline of the World Meteorological Organization(WMO). The Blocking method was cited to transpose from PMP to PMS (Probable Maximum Storm) with time distribution. The unit hydrograph, applied for the estimation of PMF was derived by Clark's method. The summaryzed results : (1) The 72 hrs duration PMP in the area is 477.3mm which is 80mm less than the PMP map in Korea and 134 mm lager than the maximum precipitation of 342.9mm in Taegu, near the Wi stream watershed. (2) According to the types of time distribution and variations of base flow, the ranges of PMF for advanced type, central type and delayed type are 3,145.3~3,348.3cms, 3,774.6~3,977.7cms and 3,814.6~4,017.3cms, respectively. Those mean that peak discharge of advanced type is 600cms less than the central type and delayed type. (3) Delayed type among three types by Blocking method has been estimated the largest PMF of 4,017.3cms, and the advanced type has been estimated the smallest PMF of 3,145.3cms. The mean value of the peak PMF of 3,653.6cms may probably be resonable PMF in the Wi stream watershed. The mean PMF could probably be 1.7 times lager than the result of Gajiyama's equation. It is equivalent to the flood of return period 1,000 to 10,000 yrs.

• Journal of Korea Water Resources Association
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• v.54 no.5
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• pp.347-354
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• 2021

In the past few years, various damages have occurred in the vicinity of rivers due to flooding. In order to alleviate such flood damage, structural and non-structural measures are being established, and one of the important non-structural measures is to establish a flood warning system. In general, in order to establish a flood warning system, the water level of the flood alarm reference point is set, the critical flow corresponding thereto is calculated, and the warning precipitation amount corresponding to the critical flow is calculated through the Geomorphological Instantaneous Unit Hydrograph (GIUH) rainfall-runoff model. In particular, when calculating the critical flow, various studies have calculated the critical flow through the Manning formula. To compare the adequacy of this, in this study, the critical flow was calculated through the HEC-RAS model and compared with the value obtained from Manning's equation. As a result of the comparison, it was confirmed that the critical flow calculated by the Manning equation adopted excessive alarm precipitation values and lead a very high flow compared to the existing design precipitation. In contrast, the critical flow of HEC-RAS presented an appropriate alarm precipitation value and was found to be appropriate to the annual average alarm standard. From the results of this study, it seems more appropriate to calculate the critical flow through HEC-RAS, rather than through the existing Manning equation, in a situation where various river projects have been conducted resulting that most of the rivers have been surveyed.