• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.1156-1160
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• 2006

본 연구는 빈도별 수문조건하의 2차원 수리해석모형(FLUMEN) 결과를 제공받아 빈도별 침수범람 등을 분석하고, 이로부터 도출되는 침수면적, 최대침수심, 최대유속 등의 특성정보를 이용하여 침수심보다 상대적으로 홍수 위험에 대한 척도를 나타내어 줄 수 있는 홍수 강도(Flood Intensity) 개념을 도입하여 대상유역에 적합한 홍수 위험지표(Flood Hazard Value) 및 홍수 위험도(Flood Risk Map)를 작성하고자 하였다. 본 연구의 대상지역은 안성천 중류부의 평택시 6개동을 포함하는 약 $12.6km^2$의 대상지역으로 2차원 수리해석모형(FLUMEN)의 분석한 시간별 침수심(Flow Depth), 최대침수심과 최대 유속 등의 결과를 ASCII파일의 XYZ값 형태로 제공받아 ArcGis 등을 이용하여 Point Coverage를 만들고, 이로부터 TIN (Triangulated Irregular Network)작업을 수행한 후 대상지역의 최대 침수심도 및 최대 유속분포도 등을 작성하였다. 그리고, 침수예상도 등으로부터 얻어진 침수면적, 최대 침수심, 최대유속 등을 분석하여 침수심과 유속의 함수로 홍수강도를 정의하고 홍수강도와 홍수발생확률의 곱으로 위험지표를 산정하였고, 산정된 홍수 위험지표를 적용하여 홍수 위험도를 작성하였다. 본 연구로부터 도출되는 홍수 위험지표 및 홍수 위험도는 홍수범람에 의한 인명피해 및 재산손실과 이에 대한 복구 및 구호활동에 소요되는 노력 등의 여러 가지 사회..경제적 역기능을 방지하고자 홍수에 의한 침수특성을 이해하고 홍수에 대비한 적절한 홍수방어대책 수립시의 지원 정보로 제공되어 활용될 수 있다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.2
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• pp.549-557
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• 2013

An flood inundation map is able to convey spatial distribution of inundation to a decision maker for flood risk management. A roughness coefficient with unclear values and a discharge obtained from the stage-discharge rating equation are key sources of uncertainty in flood inundation mapping by using a hydraulic model. Also, the uncertainty analysis needs an observation for the flood inundation, and satellite images is useful to obtain spatial distribution of flood. Accordingly, the objective of this study is to quantify uncertainty arising roughness and discharge in flood inundation mapping by using a hydraulic model and a satellite image. To perform this, flood inundations were simulated by HEC-RAS and terrain analysis, and ISODATA (Iterative Self-Organizing Data Analysis) was used to classify waterbody from Landsat 5TM imagery. The classified waterbody was used as an observation to calculate F-statistic (likelihood measure) in GLUE (Generalized Likelihood Uncertainty Estimation). The results from GLUE show that flood inundation areas are 74.59 $km^2$ for lower 5 % uncertainty bound and 151.95 $km^2$ for upper 95% uncertainty bound, respectively. The quantification of uncertainty in flood inundation mapping will play a significant role in realizing the efficient flood risk management.

• 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 the Korean Society of Hazard Mitigation
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• v.9 no.4
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• pp.71-80
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• 2009

Although desire for living without hazardous damages grows these days, threats from natural disasters which we are currently exposed to are quiet different from what we have experienced. To cope with this changing situation, it is necessary to assess the characteristics of the natural disasters. Therefore, the main purpose of this research is to suggest a methodology to estimate the potential property loss and assess the flood risk using a regional regression analysis. Since the flood damage mainly consists of loss of lives and property damages, it is reasonable to express the results of a flood risk assessment with the loss of lives and the property damages that are vulnerable to flood. The regional regression analysis has been commonly used to find relationships between regional characteristics of a watershed and parameters of rainfall-runoff models or probability distribution models. In our research, however, this model is applied to estimate the potential flood damage as follows; 1) a nonlinear model between the flood damage and the hourly rainfall is found in gauged regions which have sufficient damage and rainfall data, and 2) a regression model is developed from the relationship between the coefficients of the nonlinear models and socio-economic indicators in the gauged regions. This method enables us to quantitatively analyze the impact of the regional indicators on the flood damage and to estimate the damage through the application of the regional regression model to ungauged regions which do not have sufficient data. Moreover the flood risk map is developed by Flood Vulnerability Index (FVI) which is equal to the ratio of the estimated flood damage to the total regional property. Comparing the results of this research with Potential Flood Damage (PFD) reported in the Long-term Korea National Water Resources Plan, the exports' mistaken opinions could affect the weighting procedure of PFD, but the proposed approach based on the regional regression would overcome the drawback of PFD. It was found that FVI is highly correlated with the past damage, while PFD does not reflect the regional vulnerabilities.

• Journal of the Korean Association of Geographic Information Studies
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• v.13 no.4
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• pp.101-110
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• 2010

The increased occurrence of flooding due to typhoons and local rainfall has necessitated damage prevention through the systematic construction of damage history and quantitative analysis of flood prediction data. In this study, we constructed a disaster information map for practical use by combining digital images and continuous cadastral maps of damaged areas using a geographic information system to provide basic data and attribute information. In addition, we predicted the areas at risk of flash floods by calculating the flood capacity of the study area for different rainfall frequencies through flood inundation simulation, which was used to obtain comprehensive disaster information. Further, we calculated the extent of the flooded area and the damage rate for different rainfall frequencies using cadastral information. Flood inundation simulation in the case of heavy rainfall was found to help improve the ability to react to a flood and enhance the efficiency of rescue work by supporting decision-making for disaster management.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2004.11a
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• pp.423-428
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• 2004

Flooding is one of the main causes of loss of lives and properties among various natural disasters in Korea. Flood risk maps are currently being produced in Korea but the progress is slow considering the necessity to map at nationwide scale. In this study, GIS-based multi-criteria decision making process which is normally used for resource management and site analysis was applied to locate flood vulnerable areas. Past records of flooding maps were analysed to extract topographic characteristics of flooded areas. The extracted characteristics were then set as criteria for flooding analysis using the Fuzzy and Analytic Hierarchy Process(AHP) methodology. Results from this study showed that an improved phased action plan was possible, because the flood vulnerable areas are shown in varying degrees of uncertainty unlike the conventional Boolean type GIS layer superimposition analysis.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.5
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• pp.506-513
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• 2020

Due to climate change, there is an increasing risk of complex (hybrid) disasters, comprising rising sea-levels, typhoons, and torrential rains. This study focuses on Marine City, Busan, a new residential city built on a former landfill site in Suyeong Bay, which recently suffered massive flood damage following a combination of typhoons, storm surges, and wave overtopping and run-up. Preparations for similar complex disasters in future will depend on risk impact assessment and prioritization to establish appropriate countermeasures. A framework was first developed for this study, followed by the collection of data on flood prediction and socioeconomic risk factors. Five socioeconomic risk factors were identified: (1) population density, (2) basement accommodation, (3) building density and design, (4) design of sidewalks, and (5) design of roads. For each factor, absolute criteria were determined with which to assess their level of risk, while expert surveys were consulted to weight each factor. The results were classified into four levels and the risk level was calculated according to the sea-level rise predictions for the year 2100 and a 100-year return period for storm surge and rainfall: Attention 43 %, Caution 24 %, Alert 21 %, and Danger 11 %. Finally, each level, indicated by a different color, was depicted on a complex disaster risk map.

• Journal of Wetlands Research
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• v.16 no.3
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• pp.383-392
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• 2014

The purpose of this study is to simulate inundation and evaluate the applicability of LISFLOOD model to the streams in South Korea by comparing with the inundation map using FLUMEN. The suggested levee breaching scenarios were applied to the LISFLOOD model, and the results obtained from scenarios were evaluated. The modeling results using LISFLOOD by appling the levee breaching scenarios showed 0.2% ~ 42% relative error with FLUMEN model in inundation area. But the relative error of maximum inundation area by overlapping all the flood analysis results from levee breaching scenarios such as the way making flood risk map was approximately 1.2% between two models. Meanwhile, LISFLOOD model was easy to construct input data, DEM as topographic data and discharge hydrograph as upper boundary conditions. And computing time of LISFLOOD was shorter than FLUMEN. Therefore LISFLOOD model can be applied usefully in the region that needs immediate inundation modeling.

• Journal of Korea Water Resources Association
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• v.40 no.6 s.179
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• pp.447-458
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• 2007

In this study, the coastal urban flood prediction and warning system based on HEC-RAS and SWMM were investigated to evaluate a watershed of On-Cheon stream in Busan which has characteristics of costal area cased by flooding of coastal urban areas. The basis of this study is a selection of various geological data from the numerical map that is a watershed of On-Cheon stream and computation of hydrologic GIS data. Thiessen method was used for analyzing of rainfall on the On-Cheon stream and 6th regression equation, which is Huff's Type II was time-distribution of rainfall. To evaluate the deployment of flood prediction and warning system, risk depth was used on the 3 selected areas. To find the threshold runoff for hydraulic analysis of stream, HEC-RAS was used and flood depth and threshold runoff was considered with the effect of tidal water level. To estimate urban flash flood trigger rainfall, PCSWMM 2002 was introduced for hydrologic analysis. Consequently, not only were the criteria of coastal urban flood prediction and warning system decided on the watershed of On-Cheon stream, but also the deployment flow charts of flood prediction and warning system and operation system was evaluated. This study indicates the criteria of flood prediction and warning system on the coastal areas and modeling methods with application of ArcView GIS, HEC-RAS and SWMM on the basin. For the future, flood prediction and warning system should be considered and developed to various basin cases to reduce natural flood disasters in coastal urban area.

• Journal of the Korean Association of Geographic Information Studies
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• v.8 no.4
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• pp.71-80
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• 2005

As local flash flood exceeding planned capacity occurs frequently, localized preparedness and response to flood inundation are increasingly important. Using XP-SWMM model and GIS techniques, this study analyzes inundation areas by local flash flood and develops rainfall standards for evacuation with the case of Sadang-Cheon area, a local stream and its nearby highly populated watershed in the southern part of metropolitan Seoul, Flood inundation areas overflowed from drainage systems are analyzed and mapped by amount of rainfall that is derived from reference levels of stream flow. Rainfall standards for evacuation are comprised of 'watch' (40mm/hr) in preparing for near-future inundation and 'evacuation' (65mm/hr) in responding to realized inundation. The methods suggested by this case study may be applied to other urban areas for sound flood prevention policy measures and thus risk minimization.