• The Journal of Engineering Geology
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• v.25 no.4
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• pp.449-458
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• 2015

The compilation of a flood hazard map is an efficient technique in managing areas at risk of flooding in the case of a dam-break. A scenario-based numerical modeling approach is commonly used to compile a flood hazard map related to dam-break and to determine the model parameters that capture peak discharge, including breach formation and progress, which are important in the modeling method. This approach might be considered less reliable if an existing model is used without local validation. In this study, a dam-break model is linked to a routing model to identify flood-risk areas in the case of failure of the Sandae Reservoir Gyeongju, Gyeongbuk. Model parameters are extracted from a DEM, and maps of land use and soil texture. The simulation results are compared with on-site investigations in terms of inundation and depth. The model reproduces the inundation zone with reasonable accuracy.

• Journal of Korean Society of Disaster and Security
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• v.12 no.3
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• pp.1-11
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• 2019

This study selected the national park area of Mt. Seorak in Inje-gun, Gangwon-do, where a lot of debris flow occurred due to the heavy rainfall and conducted a field survey. In addition, topographic spatial data were constructed using the GIS technique to analyze watershed characteristics. For the construction of terrain data after the disaster, the debris flow occurrence section was scanned and the 3D topographic data was constructed using the terrestrial LiDAR. LiDAR terrain data are compared to digital maps(before disaster) to assess precision and topographic data before and after the disaster were compared and analyzed. Debris flow diffusion area was calculated using FLO-2D model and compared debris flow occurred section.

• Journal of Korean Society of Disaster and Security
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• v.15 no.4
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• pp.71-78
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• 2022

Recently, mountain disasters such as landslides and debris flows have flowed along mountain streams and hit residential areas and roads, increasing damage. In this study, in order to reduce damage and analyze causes of mountain disasters, field surveys and Terrestrial LiDAR terrain analysis were conducted targeting debris flow areas, and debris flow flow processes were simulated using FLO-2D and RAMM models, which are numerical models of debris flows. In addition, the debris flow deposition area was calculated and compared and analyzed with the actual occurrence section. The sedimentation area of the debris flow generation section of the LiDAR scan data was estimated to be approximately 21,336 ㎡, and was analyzed to be 20,425 ㎡ in the FLO-2D simulation and 19,275 ㎡ in the case of the RAMMS model. The constructed topographical data can be used as basic data to secure the safety of disaster risk areas.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.2
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• pp.261-268
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• 2018

The study used the simplified flooding analysis model, SIMOD, to distribute the total flood discharge by time, so research on flooding in urban areas can be conducted. The conventional flooding analysis models have limitations in constructing input data and take a long time for analysis. However, SIMOD is useful because it supports rapid decision-making process using quick modeling based on simple hydrological data, such as topography and inflow flood of the study area, to analyze submerged routes formed by flooding. Therefore, the study used the SIMOD model to analyze flooding in urban areas before conducting a comparative study with the outputs from FLO-2D, which is one of the conventional flooding analysis models, to identify the model's applicability. Seongseoje was selected as the study area, as it is located downstream the Geumho river where streams flow in the adjacent areas, and dikes are high enough to apply the "Overflow and Break" scenario for urban areas. With regard to topography, the study applied DEM data for the conventional flooding analysis and DSM data to represent urban building communities, distribution of roads, etc. Input flood discharge was calculated by applying the rectangular weir equation under the bank and break scenario through a 200-year return period of a design flood level. Comparative analysis was conducted in a flooded area with a simulation time of 1-24 hours. The time for the 24-hour simulation in SIMOD was less than 7 minutes. Compared with FLO-2D, the difference in flooded areas was less than 20%. Furthermore, the study identified the need for topography data using DSM for urban areas, as the analysis result that applies DSM showed the influence of roads and buildings.

• Journal of Environmental Science International
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• v.28 no.2
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• pp.211-217
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• 2019

A Numerical modeling approach is usually applied to reproduce the physical phenomena of a fill dam-break. The accuracy of the dam-break model depends on the physical structure that defines input variables such as the storage volume, breach formation and progress, and the parameters of the model, which are subjective as they are prescribed by users. In this study, a sensitivity analysis was performed for the nonlinear breach progression curve that was already developed, which includes four parameters. The study focuses on the two of the parameters which control the breach forming time and peak discharge. The model is coupled with a two-dimensional flood simulation model (FLO-2D) to examine flood coverage and depth. It is generally observed that the parameter ${\beta}$ controls only the breach forming time, the parameter ${\gamma}$ is particularly sensitive to the peak flow.

• Journal of Korean Society of Disaster and Security
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• v.15 no.2
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• pp.37-44
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• 2022

As the frequency of torrential rains and typhoons increases due to climate change, the frequency of occurrence of debris flow is also increasing. In particular, in the case of Kangwon-do, the occurrence of damage caused by mountain disasters is increasing as it has a topographical characteristic where the mountains and the coast are in contact. In order to analyze the flow characteristics in the sedimentary part of the debris flow, input data were constructed through numerical maps and field data, and a two-dimensional model, FLO-2D, was simulated. The damaged area was divided into the inflow part of the debris flow, the village center, and the vicinity of the port, and the flow center and flow velocity of the debris flow were simulated and compared with field survey data. As a result, the maximum flow depth was found to be 2.4 m at the debris flow inlet, 2.7 m at the center of the village, and 1.4 m at the port adjacent to the port so the results were similar when compared to the field survey. And in the case of the maximum flow velocity, it was calculated as 3.6 m/s at the debris flow inlet, 4.9 m/s in the center of the village and 1.2 m/s in the vicinity of the port, so It was confirmed that the maximum flow center occurred in the section where the maximum flow rate appeared.

• Journal of Environmental Science International
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• v.29 no.1
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• pp.25-32
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• 2020

The determination of soil parameters is important in predicting the simulated surface runoff using either a distributed or a lumped rainfall-runoff model. Soil characteristics can be collected using remote sensing techniques and represented as a digital map. There is no universal agreement with respect to the determination of a representative parameter from a gridded digital map. Two representative methods, i.e., arithmetic and predominant, are introduced and applied to both FLO-2D and HEC-HMS to improve the model's accuracy. Both methods are implemented in the Yongdam catchment, and the results show that the former seems to be more accurate than the latter in the test site. This is attributed to the high conductivity of the dominant soil class, which is A type.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.397-397
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• 2015

The frequency of urban floods is recently increased as a consequence of climate change and haphazard development in urban area. To mitigate and prevent the flood damage, we generally utilized a numerical model to investigate the causes and risk of urban flood. Contrary to general flood inundation model simulating only the surface flow, the model needs to consider flow of the sewer network system like SWMM and ILLUDAS. However, this kind of model can not consider the interaction between the surface flow and drainage network. Therefore, we tried to evaluate the impact of bidirectional interaction between sewer and surface flow in urban flooding analysis based on simulations using the quasi-interacted model and the interacted model. As a general quasi-interacted model, SWMM5 and FLUMEN are utilized to analyze the flow of drainage network and simulate the inundation area, respectively. Then, FLO-2D is introduced to consider the interaction between the surface flow and sewer system. The two method applied to the biggest flood event occurred in July 2011 in Sadang area, South Korea. Based on the comparison with observation data, we confirmed that the model considering the interaction the sewer network and surface flow, showed a good agreement than the quasi-interacted model.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.286-286
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• 2017

자연재난은 전 세계적으로 인명 및 재산피해를 야기하고, 근래에는 기후변화로 인한 국지성 집중호우와 태풍의 발생빈도가 증가하고 있으며, 국토면적의 64%가 산지로 이루어져 있는 우리나라에서는 산지재해의 위험 가능성이 매우 높다. 이 중 토석류 재해는 붕괴된 토사가 물과 함께 섞여 높은 농도로 하류를 향해 이동하기 때문에 그 발생시점과 발생위치를 예측하기 어렵고, 토석류의 이동경로와 퇴적부 지점에 위치하고 있는 시설물 및 인명에 매우 큰 피해를 입히는 자연재해 중 하나이다. 본 연구대상지역은 충북제천시 봉양읍 공전리 일대에 위치하고 있으며, 2009년 7월 시간최대강우량 64mm, 누적강우량 455m의 집중호우로 인해 토석류가 발생하였고, 하류부에 위치한 민가와 비닐하우스, 농경지등에 피해가 발생하였다. 이에 본 연구에서는 지상LiDAR를 활용하여 고정밀도 DEM(Digital Elevation Model)을 구축하였다. 그리고 토석류 수치모형 중 미연방재난관리청(FEMA)에서 토석류 해석에 권장하고 있는 프로그램 FLO-2D모형과 일본에서 개발된 Kanako-2D모형을 적용하여 실측된 토석류 확산범위와 유출토사량을 수치모형의 결과와 비교분석하여 모형의 적용성을 검토하였다.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.81-81
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• 2017

최근 발생하는 태풍 또는 국지성호우는 단기간에 많은 양의 강우를 동반하고 있으며, 이로인한 내수침수 및 외수범람 피해가 빈번히 발생하고 있다. 이와 같은 홍수피해를 저감하기 위한 하나의 대책으로 내수 또는 외수로 인한 피해를 미리 예측하고 대비하는 방법이 필요하다. 피해를 미리 예측하기 위한 기존의 모델들은 지표유출, 지하유출, 침투, 증발산 등 다양한 강우-유출 알고리즘에 의해 홍수범람모의를 분석하게 된다. 따라서 그 모의시간이 길게 나타나 재난상황을 대처하는 데 문제가 있다. 본 연구에서는 홍수로 인한 제내지의 침수 확산 경로 빠른 시간 안에 모의하기 위하여 여러 가지 알고리즘을 단순화시킨 홍수범람 모형을 개발하였다. 개발된 분포형 홍수범람 모형인 SIMOD(Simplified Inundation MODel)는 홍수가 발생된 시점에서 그리드화된 주변셀로의 홍수전의를 위하여 주변셀과의 경사를 이용하여 차등 분배하는 다중흐름방향법(Multi Direction Method, MDM)과, 하나의 낮은 고도의 셀에서 수위가 높아져 인접셀보다 수위가 증가하면 그 수위는 인접 셀들과 균등해 진다는 가정인 평수가정법(Flat-Water Assumption, FWA)인 두 가지 알고리즘을 이용한다. 개발된 모형의 적합성을 확인하기 위하여 상용 모형인 FLO-2D를 이용하여 각 모의시간별 침수면적과 모형의 구동시간을 비교하였다. 비교결과 초기 1시간을 제외하고 홍수피해 면적이 10% 전후로 나타나 SIMOD의 적용성이 확인되었다. 모의 구동시간의 경우 32시간 모의시 SIMOD는 10분 안에 결과가 나오는 반면 FLO-2D는 1시간 이상 소요되는 것으로 나타났다. 또한 대피계획을 수립하기 위하여 제방붕괴시나리오를 이용한 제내지 침수모의를 실시하였다. 대상지역은 금호강하류 성서산업단지 유역으로 계획홍수위는 200년 빈도 홍수위를 기준으로 하였으며 폭 35m, 높이 7m의 제방파제로 인한 외수위 유입을 가정하여 제내지의 시간별 침수면적 모의하였다. 모의된 결과를 이용하여 시간대별 대피경로를 산정함으로써 홍수로 인한 대피 계획 수립에 적용 가능함을 확인하였다.