• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.4B
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• pp.361-366
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• 2010

It would be helpful to evaluate the potential flood damage and compare quantitatively with each other when establishing the regional flood countermeasure and determining the execution of the restoration works and emergency action plans. The Flood Damage Index (FDI) in Korea, possible to estimate localized potential risks caused by flood damages, therefore, was proposed in this study. It was considered with the scale of regional flood damages including the regional characteristics and quantitative grounds. First, the four significant causes were categorized as natural, social, politic, and facilitative ones. And the eleven selected factors representing four causes were determined. Finally, the FDI was obtained by the weighting linear summation of the corrected 11 factors multiplied by the weighting values based on the professional questionnaires. Employing the FDI, the potential risk analysis about flood damages for 229 cities and counties in Korea was conducted. These results would be utilized as the essential basis for more rational and practical countermeasures and plans against flood damage.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.395-395
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• 2019

대한민국에서 홍수는 매해 여름 발생하는 자연재해로 인명, 재산, 사회 기반시설에 심각한 피해를 일으키고 있으며, 기후변화로 인해 홍수 사상이 과거와는 다른 형태이다. 이를 대비하기 위해서는 기후변화를 고려한 홍수 위험도(flood risk)를 평가를 통해 적절한 대비책을 수립하여야 한다. 이에 본 연구는 전국의 홍수위험도를 중권역 별로 평가하는 홍수위험지수(Flood Risk Index, FRI)를 새로이 개발하였다. FRI는 세 가지 세부 지표인 위협도, 노출도, 대응능력(Hazard, Exposure, Capacity)의 결합으로 산정된다. 위협도는 직접적인 홍수의 원인이 되는 기상학적 요인인 강수에 대한 정보이고, 노출도는 홍수로부터 피해를 입을 수 있는 인명 및 재산에 대한 요소이다. 대응능력은 자연 환경과 인간의 중장기 전략을 고려한 적응능력(adaptive capacity)과 홍수 발생 시 조치능력(coping capacity)으로 나눠져 평가된다. 즉 위협도와 노출도가 높을수록 홍수 위험도가 커지며, 대응능력이 뛰어날수록 홍수 위험도는 줄어든다. 인자들은 특정 유형의 위험도에만 초점이 맞춰지지 않고 다양한 방면을 포괄적으로 평가할 수 있도록 선정되었으며, 통계 기법을 활용해 FRI를 산정하였다. 크론바흐 알파 계수(Cronbach's ${\alpha}$)를 통해 FRI의 타당성을 진단하였으며, 홍수피해금액간의 스피어만(Spearman) 상관계수를 통해 FRI의 설명력을 검증해 신뢰도를 제고했다. 최종적으로 환경부로부터 제공받은 미래 기후 시나리오를 사용하여 FRI를 산출해 미래의 세 시점(2030년대, 2050년대, 2080년대)의 전국 홍수위험도 평가를 진행하였다.

• Journal of Convergence for Information Technology
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• v.9 no.11
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• pp.125-133
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• 2019

In this paper, probabilistic flood risk maps were produced for levee break caused by possible flood scenarios. The results of the previous studies were employed for flood stages corresponding to hydrological extreme event quantified uncertainties and then predicted the location of a levee breach. The breach width was estimated by combining empirical equation considered constant width and numerical modeling considered uncertainties on compound geotechnical component. Accordingly, probabilistic breach outflow was computed and probabilistic inundation map was produced by 100 runs of 2D inundation simulation based on reliability analysis. The final probabilistic flood risk map was produced by combining probabilistic inundation map based on flood hazard mapping methodology. The outcomes of the study would be effective in establishing specified emergency actin plan (EAP) and expect to suggest more economical and stable design index.

• 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 Korea Water Resources Association
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• v.48 no.12
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• pp.1037-1049
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• 2015

The most of natural disasters that occur in North Korea are flood, typhoon and damage from heavy rain. The damage caused by those disasters since the mid-1990s is aggravating North Korea's economic difficulties every year. By recognizing the seriousness of the damages from the floods, the North Korean government has carried out the river maintenance, farmland restoration, land readjustment and afforestation projects since the last-1990s, but it has failed preventing the damages. In order to estimate the degree of flood risk regarding damage from chronic floods that occur inveterately in North Korea, this research conducted an additional simulation for rainfall-runoff analysis to reflect the characteristics of the ungauged area that make foreign countries hard to obtain the hydrological data and do not open the topographical data to public. In addition, this research estimates the degree of flood risk by selecting the factors of the hazard, exposure and vulnerability by following the standards of the Intergovernmental Panel on Climate Change (IPCC).

• Journal of Wetlands Research
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• v.25 no.2
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• pp.83-90
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• 2023

Due to climate change, the occurrence of abnormal rainfall is increasing, and the intensity and scale of damage caused by heavy rain are increasing every year. In addition, as the frequency of heavy rains becomes more frequent, heavy rains often occur continuously, resulting in large flooding damage that has never been seen before in urban area. When near rivers and coastal areas are impermeable areas, the maximum flow increases rapidly as the rainfall intensity increases, so a comprehensive flood risk evaluation is needed considering the characteristics of the basin. In this study, the flood inundation risk evaluation was analyzed by giving scores on evaluation factors as a measure to prevent inundation in subway stations. Through the flood inundation risk evaluation process considering the comprehensive evaluation index, the flood risk evaluation was conducted on five urban railway stations with a large amount of traffic and floating population that had been inundated in the past. It is judged that by comprehensively analyzing this and establishing a inundation risk grade (grade 1 to 4) to establish a flood measure suitable for the risk grade.

• Journal of the Korean Society of Hazard Mitigation
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• v.11 no.3
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• pp.175-182
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• 2011

The desire for living without hazardous damages grows these days, the city strategy to make the safer community has become an issue. The global assessment for the flood index require the process considering different climate of the world cities. In this study, the actual rainfall observations of the world's major cities were collected. To compare different rainfall characteristics, we calculated some indicators such as frequency factor etc using the probable maximum precipitation. Using the results of these indicators, major cities in Korea show greater variability in the rainfall characteristics when compared to other major cities in the world. These results are expected to be useful for the development of global flood risk assessment as well as the setting the direction for future flood prevention measures.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.3
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• pp.579-588
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• 2015

Recent climage changes have resulted in increases in rainfall intensity and flood frequency as well as the risk of flood damage due to typhoons during the summer season. Water-friendly facilities such as ecological parks and sports facilities have been established on floodplains of rivers since the river improvement project was implemented and increases in the flood levels of rivers due to typhoons can lead to direct flood damage to such facilities. To analyze the hydraulic influence of these water-friendly facilities on floodplains or to evaluate their stability, numerical analysis should be performed in advance. In addition, it is crucial to address the drying and wetting processes generated by water level fluctuations. This study uses a Nays2D model, which analyzes drying and wetting, to examine its applicability to simple terrain in which such fluctuations occur and to natural rivers in which drying occurs. The results of applying this model to sites of actual typhoon events are compared with values measured at water level observatories. Through this comparison, it is determined that values of coefficient of determination ($R^2$), mean absolute error (MAE), and root-mean-square error (RMSE) are 0.988, 0.208, and 0.239, respectively, thus showing a statistically high correlation. In addition, the results are used to calculate flood risk indices for evaluation of such risk for water-friendly facilities constructed on floodplains.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.981-981
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• 2012

최근 지구환경 변화에 따른 기후변화의 영향으로 자연재해의 형태는 점차 대형화, 다양화되고 있으며 극치사상의 발생 빈도가 계속해서 증가하고 있는 추세이다. 특히 도시하천의 경우 인구와 재산이 밀집해 있어 기후변화에 따른 홍수위험 및 취약성이 클 것으로 사료된다. 본 연구에서는 기후 변화에 따른 홍수위험 및 취약성 분석을 위하여 위험도 기반 불확실성을 다루는 수단으로 UQR-MCS (Upper Quartile Range-Monte Carlo Simulation)을 적용하였으며, 다양한 형태의 확률 분포로부터 특정변량(variable)의 확률분포 Quartile을 모의하였다. 또한 기후변화에 따른 도시하천의 홍수위험 및 취약성 평가를 위하여 도시하천에 적합한 홍수위험 및 취약성평가 지수(FVI: flood vulnerability index)를 산정하였으며, 홍수취약성지수는 기후변화(Climate change)와 도시화(Urbanization), 제방월류위험(Overtopping risk) 및 홍수범람 면적(Flood area) 등의 지표를 사용하였다. 각각의 지표는 엔트로피(Entropy) 기법을 적용하여 가중치를 부여하였으며, 표준화과정을 통한 일반화된 지표 값을 산정하였다. 우이천 유역의 기후변화에 따른 홍수위험 및 취약성 지표값은 KMA RCM A1B 시나리오자료를 바탕으로 추정한 미래 확률강수량과 각 인자별 재현기간에 따른 수문변량의 변화를 통하여 산정하였다. 본 연구의 결과는 향후 도시하천의 기후변화에 따른 홍수위험도분석 및 취약성 평가, 극치 수문사상에 대한 신뢰성 있는 분석과 더불어 예상치 못할 이상홍수에 대비한 하천방재 연구에 도움이 되리라 사료된다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.5B
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• pp.489-499
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• 2006

The Potential Flood Damage (PFD) is widely used for representing the degree of potential of flood damage. However, this cannot be related with the design frequency of river basin and so we have difficulty in the use of water resources field. Therefore, in this study, the concept of Potential Risk for Flood Damage Occurrence (PRFD) was introduced and estimated, which can be related to the design frequency. The PRFD has three important elements of hazard, exposure, and vulnerability. The hazard means a probability of occurrence of flood event, the exposure represents the degree that the property is exposed in the flood hazard, and the vulnerability represents the degree of weakness of the measures for flood prevention. Those elements were devided into some sub-elements. The hazard is explained by the frequency based rainfall, the exposure has two sub-elements which are population density and official land price, and the vulnerability has two sub-elements which are undevelopedness index and ability of flood defence. Each sub-elements are estimated and the estimated values are rearranged in the range of 0 to 100. The Analytic Hierarchy Process (AHP) is also applied to determine weighting coefficients in the equation of PRFD. The PRFD for the Anyang river basin and the design frequency are estimated by using the maximum rainfall. The existing design frequency for Anyang river basin is in the range of 50 to 200. And the design frequency estimation result of PRFD of this study is in the range of 110 to 130. Therefore, the developed method for the estimation of PRFD and the design frequency for the administrative districts are used and the method for the watershed and the river channel are to be applied in the future study.