• Journal of Korea Water Resources Association
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• v.56 no.10
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• pp.667-678
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• 2023

In this study, quasi-3D inundation flow simulations were conducted for a simplified subway station configuration. The effects of variations in rainwater inflow locations and discharge were investigated, analyzing the resulting inundation flow patterns and flood risk. The inundation simulation results calculated the incipient velocities for slipping and toppling accidents to assess pedestrian safety. The results indicated that velocities exceeding the incipient velocity for slipping accidents mainly occurred on the flooded staircase. Meanwhile, velocities surpassing the incipient toppling accidents were observed around the staircase and the corridor near the staircase leading to B2F. This observation is consistent with the results from the specific force distribution analysis. To provide detailed flood risk assessments, the Flood Hazard Degree (FD) was applied with four levels of criteria, along with the Flood Intensity Factor (FIF). The results demonstrated that FD identified a broader area at risk of flood-induced consequences compared to FIF. When comparing the different inundation risk assessment methods, the specific force method tended to overestimate the risk area, whereas FIF tended to underestimate it. Furthermore, among all assessment methods, the influence of rainwater discharge was found to have a more dominant effect on flood risk assessment compared to the number of rainwater inflow locations. Additionally, the direction of inundation flow influenced the assessed risk, with collision-induced flow patterns leading to higher flood risk than those with identical flow directions.

• Journal of the Korean GEO-environmental Society
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• v.13 no.5
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• pp.59-68
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• 2012

The objective of this study is a comparison with simulation results of flood inundation by the construction techniques of river topography. For construction of river topography, the data used in this study are 1:5,000 topographic DEM, ASTER DEM and SRTM DEM provided by WMS. Also HEC-RAS and HEC-GeoRAS are applied to analyze of inundation depth and area. Flood inundations are simulated by 3 techniques in return periods and compared with the results. The results of this study are as follows; (1) Comparative analysis of the results shows that they have only a little difference in construction techniques of river topography at midsized catchment. (2) Flood inundations by ASTER DEM is to estimate larger than the other techniques in flood area (3) In case of SRTM DEM, the application can be expected to make use in the fields because of proper results in flood inundation analysis.

• Journal of Korean Society of Rural Planning
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• v.19 no.3
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• pp.51-59
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• 2013

The objective of this study was to make a map of farmland vulnerability to flood inundation based on morphologic characteristics from the flood-damaged areas. Vulnerability mapping based on the records of flood damages has been conducted in four successive steps; data preparation and preprocessing, identification of morphologic criteria, calculation of inundation vulnerability index using a fuzzy membership function, and evaluation of inundation vulnerability. At the first step, three primary digital data at 30-m resolution were produced as follows: digital elevation model, hill slopes map, and distance from water body map. Secondly zonal statistics were conducted from such three raster data to identify geomorphic features in common. Thirdly inundation vulnerability index was defined as the value of 0 to 1 by applying a fuzzy linear membership function to the accumulation of raster data reclassified as 1 for cells satisfying each geomorphic condition. Lastly inundation vulnerability was suggested to be divided into five stages by 0.25 interval i.e. extremely vulnerable, highly vulnerable, normally vulnerable, less vulnerable, and resilient. For a case study of the Jinju, farmlands of $138.6km^2$, about 18% of the whole area of Jinju, were classified as vulnerable to inundation, and about $6.6km^2$ of farmlands with elevation of below 19 m at sea water level, slope of below 3.5 degrees, and within 115 m distance from water body were exposed to extremely vulnerable to inundation. Comparatively Geumsan-myeon and Sabong-myeon were revealed as the most vulnerable to farmland inundation in the Jinju.

• Korean Journal of Hydrosciences
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• v.10
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• pp.59-72
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• 1999

FIAS(Flood Inundation Analysis System) using Arc/Info is developed and applied to the Namhan River basin. The DWOPER model is revised and expanded to handle simultaneous multiple overtopping and/or breaking, and to estimate the inundated depth and extents. The model is applied to an actual levee overtopping case, which occurred on August 23∼27, 1995 in the Namhan River. Stage hydrographs inside and outside of the levee are compared, then inundated discharges from overbank spilling are computed. The Graphic User interface is developed with AML. Two- and three-dimensional inundation map by Arc/Info are presented. The computed inundation extends agree with observations in terms of inundated depth and flooded area. The FIAS is useful for the analysis of flood hazards and preparation of inundation map for river basins.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.179-182
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• 2008

This study simulated the flood inundations of the Nakdong River catchment running through Yangsan, a small city located in the south eastern area of Korea by using the depth averaged two-dimensional hydrodynamic numerical model. The numerical model employs the staggered grid system including moving boundary and a finite different method to solve the Saint-Venant equations. A second order upwind scheme is used to discretize the nonlinear convection terms of the momentum equations, whereas linear terms are discretized by a first order leap-frog scheme(Cho and Yoon, 1998). The numerical model was applied to a real topography to simulate the flood inundation of the Yangsan basin. The numerical results for urban district are visualized in three dimension. These results can be essentially utilized to construct the three dimensional inundation map after building the GIS-based database in local public organizations in order to protect the life and property safely.

• Journal of Korea Water Resources Association
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• v.49 no.9
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• pp.773-787
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• 2016

A coupled river-overland hydrodynamic model was applied to estimate flood risk by a scenario-based approach. The study area is Seongseo Industrial Complex in Daegu which is located near Nakdong river and Geumho river. Inundation depth and velocity at each time were calculated by applying a coupled 1D/2D hydrodynamic model to the target area of interest. The 2D inundation analysis for river and overland domain was performed with the scenario-based approach that there are levee overflow against 100/200 year high quantile (97.5%) design flood and levee break against 100/200 year normal quantile (50%) design flood. The level of flood risk was displayed for resident/industrial area using information about maximum depth and velocity of each node computed from the 2D inundation map. The research outcome would be very useful in establishing specified emergency action plans (EAP) in case of levee break and overflowing resulting from a flood.

• Journal of the Korean Association of Geographic Information Studies
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• v.19 no.1
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• pp.106-119
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• 2016

Flood risk map, flood damage map, disaster information map, inundation trace map are involved with the cartographic analysis of flood inundation based on prevention, preparation, restoration, response from natural disasters such as flood, flooding, etc. In this study, the analysis for channel and basin characteristics Chungju dam to Paldang dam of South han river after four river project. Flood scenario is selected to take advantage of design flood level of schematic design for river. Flood inundation of one dimensional non-uniform flow by using HEC-RAS with basin characteristics is accomplished and two dimensional unsteady flow was interpreted by using FLUMEN. Frequency analysis is carried out about each abundance of South han river for 100 year period, 200 year period and 500 year period. Flooding disaster area of 100 year period on 0.5m damage functions is 2378.8ha, 200 year period on 0.5m damage functions is 3155.2ha, 500 year period on 0.5m damage functions is 3995.3ha respectively. It will be significant data for decision making to establish inundation trace map for providing basic plan for river maintenance, land use plan, flood protection plan, application plan and getting information of flood expectation area.

• Journal of Korea Water Resources Association
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• v.50 no.5
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• pp.315-324
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• 2017

In this study, the HEC-GeoRAS model was used to estimate the changes of flood inundation depth and area of the Hyeoam-cheon basin after the channel migration and river improvement. The target area was extremely damaged due to the heavy rainfall on 25th August, 2014 after the costruction. According to the results of the analysis, the HEC-GeoRAS model can be used to accurately estimate the changes of flood innundation depth and area in agrecultural lands and lowlands of which the topographic changes and elevation differences are small. The inundation depths were increased 0.99 m in heavy rainfall and 0.39 m in 100 year frequency flood. The inundation areas in 100 year frequency flood were reduced in inundation depths under 1.5 m while they were increased in depths above 4.5 m. It was concluded that the loss of natural resevoir capacity of agricultural lands and lowlands due to the channel migration and river improvement caused the damage of flood in 2014 and the decrease of actual effective widths of the channel added the damage.

• Journal of Korean Society of Water and Wastewater
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• v.23 no.6
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• pp.711-717
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• 2009

In this study, SWMM model is used to reproduce the main storm sewer system located in the Nae-Hang drainage basin of the Mokpo city and keep track of flood discharge. Given the outlet of the reaches border the coastline, this paper has taken the dual-drainage approach to perform inundation simulation, considering both the overflows and inflows at the manholes of the sewer system, and at the same time, taking the impacts of tidal stage into consideration. The following conclusions are reached in this study: First, when planning lowland sewer system alongside the coastline or the riverside, the tidal stage or flood stage need to be considered in the planning and design processes. Second, an analysis that fails to consider overflow and inundation at the manholes may overestimate inundation depth of the flooded area. In other words, in order to estimate flood discharge and flood stage in a lowland storm sewer system, it is desirable to analyze the conveyance capacity of storm sewer system and simulate overflow and inundation at the manholes at the same time.

• Journal of Korea Water Resources Association
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• v.31 no.4
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• pp.415-427
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• 1998

FIAS (Flood Inundation Analysis System) using Arc/Info is developed and applied to the South Han River basin. The DWOPER model is revised and expanded to handle simultaneous multiple overtopping and/or breaking and to estimate the inundation depth and extents. The model is applied to an actual levee overtopping case, which occurred on August 23~27, 1995 in the South Han River. Stage hydrographs inside and outside of the levee are compared, then inundated discharges from overbank spilling are computed. The Graphic User Interface is developed with AML(Arc/Info Macro Language). Two-and three-dimensional inundation maps by Arc/Info are presented. The computed inundation extends agree with observations in terms of inundation depth and flooded area. Keywords : River, Floodwave, Flood Inundation, Geographic Information System.