• Journal of Korea Water Resources Association
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• v.33 no.S1
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• pp.89-94
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• 2000

• Journal of Industrial Technology
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• v.29 no.A
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• pp.111-122
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• 2009

In this study, flood stage was computed by HEC-RAS, 1-D numerical analysis model and FESWMS-2DH, 2-D numerical model. Flood stages computed by two different models were compared for straight line, dot axle watercourse, dead-zone watercourse, section sudden-changing watercourse, and curved watercourse. From the results, flow velocity and water level were similar in straight watercourse and dot-reduction watercourse. However, there was difference of flow velocity and water level in dead-zone watercourse, sudden expansion, dot-reduction, and curve-watercourse. This result might be influenced by rapid change of watercourse due to dead-zone, the angle of inflow and outflow, and the curvature. Especially in this study, numerical model was applied to Wol-Song-Cheon at Chuncheon in order to analyze the effect of flood stage by two different models. By flowing properties around the bridge and confluence of rivers, it was found that flow velocity and water level was changed. Therefore, it was concluded that a lot of uncertainties are contained in the present bank.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.135-140
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• 2008

최근 들어 이상기후로 인한 집중호우가 빈발하고 있으며, 이로인한 피해가 증가하고 있다. 실례로 2002년 발생한 태풍 루사의 경우, 가능최대강수량(PMP)에 근접한 강우강도를 보였으며, 최근 발생하고 있는 국지성 호우의 경우도 시간을 고려할 때 상당히 큰 강우강도를 보이고 있음을 알 수 있다. 이에 본 연구에서는 가능최대강수량과 댐과의 관계를 분석하기 위하여 태풍 루사의 강우 사상을 대상으로 소양강 댐의 붕괴를 고려한 시나리오와 붕괴되지 않은 시나리오로 구분하여 홍수량을 모의하였다. 강우사상의 경우, 건교부에서 2004년에 제시한 방법을 이용하여 공간분포를 시킨 후, 공간 분포된 강우를 대상으로 Huff 2분위를 적용하여 시간분포 시켰다. 또한 공간분포를 적용하지 않은 강우를 같은 방법으로 시간분포를 시킨 후, 각각의 결과를 비교분석하였다. 댐 붕괴해석을 위한 모형으로는 미육군공병단(USACE)에서 제공하는 HEC-HMS 3.1.0을 사용하였다. 분석결과 댐 붕괴를 하지 않았을 때 공간분포를 적용하는 경우가 공간분포를 적용하지 않는 경우에 비해서 지속시간이 1시간$\sim$18시간 까지는 가능최대강수량 및 첨두홍수량이 작게 모의되었으며, 18시간 이상의 지속시간을 가지는 경우에는 각각 더 크게 모의됨을 알 수 있었고 댐이 붕괴하는 경우에는 불규칙한 값을 갖게 되는 것을 볼 수 있다. 또한 태풍 루사시 소양강 댐이 붕괴되었다면, 첨두 홍수량은 2.5배가량 증가된 것으로 모의되었다.

• KCID journal
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• v.5 no.1
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• pp.8-19
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• 1998

The existing flood runoff models, Complex Hydrograph and HEC-1, have some problems which do not properly represent runoff characteristics on the Korean paddy basin and their basin slopes. In this study, FAS(Flood ,Analysis System) was developed in order t

• Journal of Wetlands Research
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• v.15 no.1
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• pp.91-103
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• 2013

In this Research, in order to improve problems of not enough technical validation and structural and hydraulic stability evaluation when nature-friendly revetment block is applied to field, hydraulic stability evaluation according to hydraulic behavior change of porosity soil block for vegetation reinforcement that secures ecological function was reviewed. By selecting object section, numerical analysis and hydraulic model experiments were performed; for numerical analysis, by using 1-dimensional numerical analysis model HEC-RAS and 2-dimensional numerical analysis RMA-2, one-dimensional(1D) and two-dimensional(2D) numerical analysis were performed; by applying Froude's similarity law, reduced-scale hydraulic model experiments according to vegetation existence were performed. In hydraulic model experiment, for validity of experiment result, the result of velocity and tractive force of reduced-scale hydraulic model experiments was converted to prototype so that it can be compared and reviewed under the same condition of one-dimensional(1D) and two-dimensional(2D) numerical analysis result; as a result, it was confirmed that comparatively united result appeared, and by comparing prototype-converted tractive force result with revetment's allowable tractive force coming from an existing research, block's hydraulic stability was suggested.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.6
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• pp.129-136
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• 2008

The purpose of this study is to find an effective operating system for water supply of Andong Dam. The reliability of water supply was assessed by HEC-5 model based on operated water supply data of Andong Dam and data of Jin-dong water level gauge station in Nak- dong river. In addition, estimated additional amount of water supply was evaluated for each alternative by additional retention of Andong Dam in rainy season from June to September. As the result, additional amount of water supply of each alternative in non-rainy season (excluding rainy season) is increased as $1.35m^3/s{\sim}2.12m^3/s$, it shows that additional amount of water supply can be made by effective operating system for water supply in every dam as Andang Dam.

• Journal of the Korean Society of Hazard Mitigation
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• v.1 no.3 s.3
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• pp.93-102
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• 2001

In this study, the characteristics of river bed profile fluctuation are become possible to be used effectively in future estimation of Taehwa river general development plan through analysis and examination according to the effects of sediment protection weir located in the area of the estuary of Taehwa river's main channel using HEC-6 model. The flow conditions needed in analysis of the characteristics of river bed profile fluctuation refer the conditions of flow which secures 95 days in a year, flood flow, and design flood examined in the estimation of Taehwa river maintenance basic plan. First, in analysis result of river bed variation range, there is no significant variation in upstream section from Samho-gyo while there are the more active erosion and sedimentation as the more flow in downstream from Samho-gyo. Next, from the result of the capacity of sediment transfer, it is analyzed that sediment transfer capacity in the area of estuary of Taehwa river has no significant difference in before and after removal of the sediment protection weir when design flood flows while it is estimated that the more flow, the bigger sediment transfer capacity. Therefore, it is thought that the installation of a suitable hydraulic structure at the lowest point of Dong-chun tributary joins from the downstream of Taehwa river can be a good device to reduce the accumulation of sediments at the lowest point of Taehwa river considering the reduction plan of sediment inflow caused by removal of the sediment protection weir.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.6B
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• pp.589-598
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• 2010

When the hydraulic structures, such as bridge and weir, are consecutively installed to a short section of a river with complicated cross section, analyzing the flow characteristics and the riverbed change modality of the river is very important. In the 250 m section of the Taehwa river near the Samho-bridge, which passes through Ulsan city, three bridges has been installed, and the tributary water is flowing into both up and downstream of the section. Due to these factors, when the flood occurs, the cross section of the river changes vastly by the water level change and scour. Even so, due to the fact that the Samho-bridge divides the section into two parts, the national river and the regional river, each part is being analyzed separately by the onedimensional model. In this study, the flow characteristics due to the bridge concentration and the tributary water inflow were jointly analyzed for both up and downstream by using the one-dimensional HEC-RAS model and the two-dimensional SMS model, such as RMA2. The riverbed change modality of the section was also investigated by using the SED2D model. The results showed that the water level difference between the HEC-RAS and RMA2 was 0.87 m when applied to the three consecutive bridges. The riverbed change simulation using SED2D showed that the maximum scour was 0.231 m and it occurred at the Samho-bridge, which located in the middle and has short pier distance. In conclusion, when planning the river maintenance for the regions with concentrated bridges or the sections with severe changes in cross-section and flow, estimating the flood elevation by two-dimensional model and establishing countermeasures for the scouring of the bridge are required. In addition, an integrated analysis on both the national river and the regional river is necessary.

• Journal of Korea Water Resources Association
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• v.44 no.9
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• pp.695-710
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• 2011

Manning's roughness coefficients for the Han River, the Nakdong River and the Geum River were determined by the hydraulic models using their field measurements. The roughness coefficients of present study were compared with the ones of the conventional references. The hydraulic models, such as HEC-2, HEC-RAS and FLDWAV models, are usually applied to a river flow analysis. In order to compute the accurate flood level with the numerical models, accurate information about river sections, the upstream and downstream boundary conditions, and the appropriate roughness coefficients are indispensable. It is hard to obtain the reasonable roughness coefficient of the river, in the other hand the river cross sectional data and the boundary conditions are relatively easy to acquire. The coefficient values from the references are applied in many applications without considering the variation of locations and discharges of the river, or the values are unreasonably estimated. The final results from this study will give a reasonable and important data to perform the flood routing in the Korea river.

• Journal of Wetlands Research
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• v.11 no.1
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• pp.49-64
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• 2009

Rainfall-runoff models are used for efficient management, distribution, planning, and design of water resources in accordance with the process of hydrologic cycle. The models simplify the transition of rainfall to runoff as rainfall through different processes including evaporation, transpiration, interception, and infiltration. As the models simplify complex physical processes, gaps between the models and actual rainfall events exist. For more accurate simulation, appropriate models that suit analysis goals are selected and reliable long-term hydrological data are collected. However, uncertainty is inherent in models. It is therefore necessary to evaluate reliability of simulation results from models. A number of studies have evaluated uncertainty ingrained in rainfall-runoff models. In this paper, Meta-Gaussian method proposed by Montanari and Brath(2004) was used to assess uncertainty of simulation outputs from rainfall-runoff models. The model, which estimates upper and lower bounds of the confidence interval from probabilistic distribution of a model's error, can quantify global uncertainty of hydrological models. In this paper, Meta-Gaussian method was applied to analyze uncertainty of simulated runoff outputs from $Vflo^{TM}$, a physically-based distribution model and HEC-HMS model, a conceptual lumped model.