• Journal of Korea Water Resources Association
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• v.39 no.1 s.162
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• pp.1-9
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• 2006

Recently, the flood damages including losses of human lifes and property have been rapidly increased according to extreme floods. And we know that the flood control project is needed for diminishing flood damages. However, we have had the lacks in a reasonable methodology for the economic analysis of food control project. This study aims to improve the existing economic analysis method for flood control project. So, first of all, we understand the problems of existing economic analysis and investigate the methodologies of foreign countries. Based on that, the Multi-Dimensional Flood Damage Analysis(MD-FDA) is developed in this study. The survey of properties on the floodplain is conducted, then the damage rate obtained by evaluating the monetary values of surveyed property is applied, and the expected flood damage is calculated. Also by considering damage area in the floodplain as well as spatial distribution of inundated depth using GIS, the flood damages are evaluated more accurately than existing method. From the study, we know that the MD-FDA can improve the problems of existing method and evaluate the reasonable flood damages by using updated nation리 statistics.

• Journal of Korea Water Resources Association
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• v.54 no.11
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• pp.925-932
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• 2021

A drought-flood abrupt alternation event is an overlapping extreme event that is harder to cope with than a single event of drought and flood. It is also expected to have a significant adverse impact on ecosystems as well as industries and agriculture. However, there has not yet been a comprehensive study that characterizes the drought-flood abrupt alternation events in Korea. Therefore, this study employed a standard weighted average precipitation (SWAP) index, which is efficient to analyze not only individual events of drought and flood but also the drought-flood abrupt alternation events considering various time scales. The SWAP standardized the weighted average precipitation (WAP) by adding temporal weights to the precipitation. The SWAP indices were calculated for middle-sized watersheds of the Han River basin using the area average precipitation during 1966 and 2018. The severity K was calculated to represent the relative regional severity considering normal rainfalls, and used to characterize the drought-flood abrupt alternation in the study areas. The results indicated that 20 of the 30 middle-sized watersheds in the Han River basin were confirmed to increase the severity of drought-flood abrupt alternation over time. Considering the frequency and severity of drought-flood abrupt alternation events in each watershed, vulnerable areas and dangerous areas due to drought-flood abrupt alternation were identified, for example, the Upstream Namhan River (#1001).

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1998.10a
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• pp.318-324
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• 1998

This study was conducted to derive optimal design floods by Generalized Extreme-value(GEV) distribution for the annual maximum series at ten watersheds along Han, Nagdong, Geum, Yeongsan and Seomjin river systems. Adequacy for the analysis of flood data used in this study was established by the tests of Independence, Homogeneity, detection of Outliers. L-coefficient of variation, L-skewness and L-kurtosis were calculated by L-moment ratio respectively. Parameters were estimated by the Methods of Moments and L-Moments. Design floods obtained by Methods of Moments and L-Moments using different methods for plotting positions in GEV distribution were compared by the relative mean and relative absolute error. It was found that design floods derived by the method of L-moments using weibull plotting position formula in GEV distribution are much closer to those of the observed data in comparison with those obtained by method of moments using different formulas for plotting positions in view of relative mean and relative absolute error.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.66-70
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• 2011

최신의 수치 해석 방법을 적용하여 개발되고 있는 자유 유체역학 소프트웨어를 소개하고, 비교적 사용이 용이한 자유 소프트웨어 Gerris를 홍수범람 모의에 활용한 결과를 보여주고자 한다. 도시 지역 돌발 홍수 범람 모의를 위한 Gerris의 신뢰도 검증을 위해 Gerris를 유럽 IMPACT(Investigation of Extreme Flood Processes and Uncertainty) 프로젝트에서 수행한 도시지역 홍수실험을 모의하는데 적용해 보았으며, 모의 결과는 실험 결과와 비교적 잘 일치하여 Gerris가 도시 지역 돌발 홍수 모의에 적합함을 보여주고 있다. 학교 및 연구기관을 중심으로 Gerris와 같은 자유 소프트웨어를 널리 활용하고 개발에 참여할 경우, 국내 홍수범람 수치모형의 개발 역량이 강화되는 토대를 만들 수 있을 것이며, 수공학 전문가는 최신의 소프트웨어를 저비용으로 하천 관리 및 홍수 관리에 활용할 수 있을 것으로 기대된다.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.126-126
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• 2021

Stormwater reduction plays an important role in the safety and resilience to flooding in urban areas. Due to rapid climate change, the world is experiencing abnormal climate phenomena, and sudden floods and concentrated torrential rains are frequently occurring in urban basins and the amount of outflow due to stormwater increases. In addition, the damage caused by urban flooding and inundation due to extreme rainfall exceeding the events that occurred in the past increases. To solve this problem, water supply, drainage, and water supply for sustainable urban development, the water management paradigm is shifting from sewage maintenance to water circulation and water-sensitive cities. So, in this study, The purpose of this study is to examine measures to increase the resilience of urban ecosystem systems for urban excellence reduction by analyzing the effects of green infra structures and LID techniques and evaluating changes in resilience. In this study, for simulating and analysis of runoff for various stormwater patterns and LID applications, Storm Water Management Model (SWMM) was used.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.121-121
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• 2020

Varying dominant processes, including Tropical Cyclone (TC) and non-TC rainfall events, have been known to drive the occurrence of precipitation in South Korea. With the changes in the pattern of the Earth's climate due to anthropogenic activities, nonstationarity or changes in the magnitude and frequency of these dominant processes have been separately observed for the past decades and are expected to continue in the coming years. These changes often cause unprecedented hydrologic events such as extreme flooding which pose a greater risk to the society. This study aims to take into account a more reliable future climate condition with two dominant processes. Diverse statistical models including the hidden markov chain, K-nearest neighbor algorithm, and quantile mappings are utilized to mimic future rainfall events based on the recorded historical data with the consideration of the varying effects of TC and non-TC events. The data generated is then utilized to the hydrologic model to conduct a flood frequency analysis. Results in this study emphasize the need to consider the nonstationarity of design rainfalls to fully grasp the degree of future flooding events when designing urban water infrastructures.

• Journal of Urban Science
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• v.12 no.2
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• pp.1-6
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• 2023

Due to abnormal climate patteZns, recent extreme weather events such as floods, occurring more frequently than once in a century, have become a common occurrence. This has resulted in frequent urban flooding due to the inadequate capacity of sewage pipelines, originally designed to handle floods occurring once every 20 to 30 years. To tackle this situation, measures such as partial flow retention through reservoirs, flood control facilities, and underground tanks have been implemented. In this study, the Storm Water Management Model, a sewage pipeline model developed by the U.S. Environmental Protection Agency (U.S. EPA), was used to analyze the flow capacity of sewage pipelines on the campus of Daegu University and to conduct research on pollutant reduction through superior control facilities. When the allowable flow velocity, ranging from 0.8 m/s to 3.0 m/s, could not be met, the slope of the sewage pipeline was adjusted through step junctions. The simulation demonstrated a 20% reduction in peak flow, decreasing from 0.69 cm/s to 0.55 cm/s, through the implementation of flow regulation facilities. It is anticipated that the findings of this study can serve as valuable data for adjusting flow velocity and reducing peak flow within the pipelines.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.6
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• pp.1919-1924
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• 2014

Recently, due to the climate change, the frequency and intensity of extreme rainfall events have been continuously increased in regions of South Korea. As a consequence, safety issues have been raised especially in the hydrologic safety of old dams designed and constructed by the old standards. In general, for improving hydrologic safety of existing dams, two options are considered: 1) raising dam crest; and 2) constructing or expanding an emergency spillway. In this process, the main criteria of alternative selection are overtopping possibility and cost efficiency of each alternative. This approach is easy to implement but it is subject to major limitation for the proper evaluation of alternatives, overlooking downstream flood damages by any controlled flow of water that is intentionally released from dams to eliminate the possibility of overtopping. Therefore, this study suggests a framework for evaluating the dam safety strengthening alternatives in terms of a comprehensive flood control by applying the concept of resilience. The case study shows that the resilience-based evaluation framework which considering downstream flood damages is effective in the selection of dam safety strengthening alternatives.

• Journal of Wetlands Research
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• v.12 no.1
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• pp.33-40
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• 2010

In this study, it has been intended to present the ways to improve some problems such as the difficulty of using the program which had got from the existing study, the computation and application of a lot of parameter and the complicated processing which need to be more simplified. Also It has been tried to bring up the ways to make a flood inundation map and a detailed inundation analysis which could reduce the risk factors. We selected an Anseong-Cheon basin, and wrote a flood inundation scenario based on extreme flood to exceed the planned frequency to consider only overflow and levee break and executed inundation simulation. Researchers conducted an analysis of overflow and levee break using function of HEC-RAS Storage with a One-Dimensional model. It applied Elevation versus Volume Curve for more correct inundation simulation than a method of Area-Time-Depth which used in popular. This study will suggest a mathematical method of SURFER with a little difference of inundation area more simplified and precise flood inundation than complicated Arcview 3.2a which used Query method of Arcview 3.2a.

• Journal of The Korean Society of Agricultural Engineers
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• v.62 no.6
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• pp.85-95
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• 2020

According to the standard guidelines of design flood (MLTM, 2012; MOE, 2019), the design flood is calculated based on past precipitation. However, due to climate change, the frequency of extreme rainfall events is increasing. Therefore, it is necessary to analyze future floods' volume by using climate change scenarios. Meanwhile, the standard guideline was revised by MOE (Ministry of Environment) recently. MOE proposed modified Huff distribution and new CN (Curve Number) value of forest and paddy. The objective of this study was to analyze the change of flood volume by applying the modified Huff and newly proposed CN to the probabilistic precipitation based on SSP and RCP scenarios. The probabilistic rainfall under climate change was calculated through RCP 4.5/8.5 scenarios and SSP 245/585 scenarios. HEC-HMS (Hydrologic Engineering Center - Hydrologic Modeling System) was simulated for evaluating the flood volume. When RCP 4.5/8.5 scenario was changed to SSP 245/585 scenario, the average flood volume increased by 627 ㎥/s (15%) and 523 ㎥/s (13%), respectively. By the modified Huff distribution, the flood volume increased by 139 ㎥/s (3.76%) on a 200-yr frequency and 171 ㎥/s (4.05%) on a 500-yr frequency. The newly proposed CN made the future flood value increase by 9.5 ㎥/s (0.30%) on a 200-yr frequency and 8.5 ㎥/s (0.25%) on a 500-yr frequency. The selection of climate change scenario was the biggest factor that made the flood volume to transform. Also, the impact of change in Huff was larger than that of CN about 13-16 times.