• Journal of The Korean Society of Agricultural Engineers
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• v.60 no.5
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• pp.135-147
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• 2018

The objective of this study was to analyze the characteristics of combined 1D/2D inundation simulation of riverside farmland using the Hydrologic Engineering Center - River Analysis System (HEC-RAS). We compared and analyzed inundation simulation results between 1D and combined 1D/2D hydraulic simulation using HEC-RAS. Calibration and validation of stream stage were performed using three rainfall events. The coefficient of determination ($R^2$) and root mean square error (RMSE) between simulated and observed stream stage were 0.935 - 0.957 and 0.250 m - 0.283 m in calibration and validation, respectively. The inundation area showed no significant difference in 1D and combined 1D/2D simulation ($8.48km^2$ in 1D simulation, $8.75km^2$ in combined 1D/2D simulation). The average inundation depth by 1D simulation was 1.4 m deeper than combined 1D/2D simulation. In the lower inundation depth, the inundation area by combined 1D/2D simulation was larger than inundation area by 1D simulation. As the inundation depth increased, the inundation area by 1D simulation became wider. In the case of the 1D/2D combined simulation, low elevation areas along the river bank were inundated widely. Compared to 1D/2D combined simulation, the flood radius in some sections was longer in 1D simulation. In the 1D analysis, because the low altitude riverside farmlands are also assumed to stream, it is calculated that riverside farmlands have the same stage as the mainstream when the stream is overflowed. Therefore, the inundation area seems to be overestimated in those sections. In other regions, the inundation areas tend to be broken depending on overflow by each stream cross-section. In the case of river flooding, the overflow is expected to flow to the lower area depending on the terrain, such as the results of the combined 1D/2D simulation. It is concluded that the results of combined 1D/2D inundation simulation reflected the topographical characteristics of low-lying farmland.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.221-223
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• 2008

It is the best way that to make an inundation map and distribute it to inhabitants for the purpose of decreasing damage of tsunami. To make an inundation map, tsunami which broughthuge damage to Korea should be properly investigated and maximum inundation zonewas selected by simulating tsunami phenomenan. An inundation map must involve the location of shelters and evacuation routes. New evacuation simulation program connected evacuation simulation procedure and tsunami inundation procedure to get inhabitants' evacuation states in real-time.

• Journal of The Korean Society of Agricultural Engineers
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• v.46 no.5
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• pp.107-116
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• 2004

A GIS-based paddy inundation simulation system which is capable of simulating temporal and spatial inundation processes was established and applied in this paper. The system is composed of HEC-GeoHMS, and HEC-GeoRAS modules which interface the GIS and flood runoff models, and HEC-HMS, and HEC-RAS models which estimate the flood runoff. It was used to simulate storm runoff and inundation for a small rural watershed, the Baran HP#7, which is 10.69 $km^2$ in size. The simulated peak runoff, time to peak, and total direct runoff for eight storms were compared with the observed data. The results showed that the coefficient of determination ($R^2$) for the observed peak runoff was 0.99 and an error, RMSE, 11.862 $m^3$/s for calibration stages. In the model verification, $R^2$ was 0.99 and RMSE 1.296 $m^3$/s. Paddy inundation for each paddy growing stages in study watershed were estimated using verified inundation simulation system when probability rainfall was applied.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.2
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• pp.307-318
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• 2015

In this study, the efficiency of two-dimensional inundation analysis using road network was demonstrated in order to reduce the simulation time of numerical model in urban area. For this objective, three simulation conditions were set up: Case 1 considered only inundation within road zone, while Case 2 and 3 considered inundation within road and building zone together. Accordingly, Case 1 used grids generated based on road network, while Case 2 and 3 used uniform and non-uniform grids for whole study area, respectively. Three simulation conditions were applied to Samsung drainage where flood damage occurred due to storm event on Sep. 21, 2010. The efficiency of suggested method in this study was verified by comparison the accuracy and simulation time of Case 1 and those of Case 2 and 3. The results presented that the simulation time was fast in the order of Case 1, 2 and 3, and the fit of inundation area between each case was more than 85% within road zone. Additionally, inundation area of building zone estimated from inundation rating index gave a similar agreement under each case. As a result, it is helpful for study on real-time inundation forecast warning to use a proposed method based on road network and inundation rating index for building zone.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.30 no.6_2
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• pp.631-642
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• 2012

This study aims to predict inundation and flood-stricken areas more accurately by simulating flood damage caused by reversible flow of rain water in the upper water system through precise 3D terrain model and backwater output. For the upstream of the South Han-River, precise 3D terrain model was established by using aerial LiDAR data and backwater by area was output by applying the storm events of 2002 including the history of flood damage. The 3D flood simulation was also performed by using GIS Tool and for occurrence of related rainfall events, inundation events of the upriver region of water system was analyzed. In addition, the results of flood simulation using backwater were verified by making the inundation damage map for the relevant area and comparing it with flood simulation's results. When comparing with the results of the flood simulation applying uniformly the gauging station's water surface elevation used for the existing flood simulation, it is found that the results of the flood simulation using backwater are close to the actual inundation damage status. Accordingly, the causes of flood occurred in downstream of water system and upstream that has different topographic characteristics could be investigated and applying the simulation with backwater is proved more proper in order to procure accuracy of the flood simulation for the upriver region.

• Water Engineering Research
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• v.2 no.2
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• pp.75-87
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• 2001

A new moving boundary technique for leap-frog finite difference numerical mode is proposed for the resonable simulation of coastal inundation over discontinuous topography. The new scheme improves the moving boundary technique developed by Imamura(1996). The present scheme is tested using the analytical solution of Thacker(1981) for the case of free oscillation with moving boundary in a parabolic bowl. Finally, a numerical simulation is conducted for the flooding over a tidal barrier constructed on a simple concave geometry. A general feature of inundation over a discontinuous topography is well described by the numerical model.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.3
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• pp.157-164
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• 2008

A modeling and visualization system of flood inundation in natural river, FloodViz, has been developed. Unsteady river flow and flood inundation are calculated by FLDWAV model. FLDWAV model and HEC-RAS model have been applied to a flood event at the same time to check model reliability. Simulation results of the two models showed good agreements. Flood propagation and inundation process can be analyzed accurately and easily by using visualization function of the FloodViz. Even though FloodViz users don't know well about both hydraulics and hydrology, they can understand flood inundation phenomena easily. This system can be used as a useful tool in forecasting flood inundation and observing the simulation results. Countermeasures for natural disaster prevention due to flood inundation can be established rapidly by using the FloodViz.

• Journal of The Korean Society of Agricultural Engineers
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• v.66 no.1
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• pp.49-66
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• 2024

Extreme rainfall will become intense due to climate change, increasing inundation risk to agricultural land. Hydrological and hydraulic simulations for the entire watershed were conducted to analyze the impact of climate change. Rainfall data was collected based on past weather observation and SSP (Shared Socio-economic Pathway)5-8.5 climate change scenarios. Simulation for flood volume, reservoir operation, river level, and inundation of agricultural land was conducted through K-HAS (KRC Hydraulics & Hydrology Analysis System) and HEC-RAS (Hydrologic Engineering Center - River Analysis System). Various scenarios were selected, encompassing different periods of rainfall data, including the observed period (1973-2022), near-term future (2021-2050), mid-term future (2051-2080), and long-term future (2081-2100), in addition to probabilistic precipitation events with return periods of 20 years and 100 years. The inundation area of the Aho-Buin district was visualized through GIS (Geographic Information System) based on the results of the flooding analysis. The probabilistic precipitation of climate change scenarios was calculated higher than that of past observations, which affected the increase in reservoir inflow, river level, inundation time, and inundation area. The inundation area and inundation time were higher in the 100-year frequency. Inundation risk was high in the order of long-term future, near-term future, mid-term future, and observed period. It was also shown that the Aho and Buin districts were vulnerable to inundation. These results are expected to be used as fundamental data for assessing the risk of flooding for agricultural land and downstream watersheds under climate change, guiding drainage improvement projects, and making flood risk maps.

• Spatial Information Research
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• v.18 no.1
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• pp.49-56
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• 2010

Considering the flood problem in urban areas, it is important to estimate disaster risk using accurate numerical analysis for inundation. In this study, it is carried out to calculate inundation depth in Samcheok city which suffered from serious flood damage in 2002. The urban flood model was developed by cording Manning n, elevation, and building's rare on ArcGIS for reducing error on data exchange, and applied for estimating flood damage by grid. This paper describes the extraction of sewer lines and buildings area, estimates its influence on flood inundation extent, and integrated 1D/2D flow to simulate inundation depth in high-density building area. This paper shows an integrated urban flood modeling including rainfall-runoff, inundation simulation, and mathematical flood damage estimation, and will serve drainage design for reducing its damage.

• Smart Media Journal
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• v.11 no.7
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• pp.52-60
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• 2022

Due to global warming and changes in the natural environment, flood damage to agricultural land due to wind and flood damage continues. Although disaster prevention projects have been continuously carried out since the founding of the country, progress has been insufficient compared to the sustained period, and huge costs are still being consumed. Therefore, it is necessary to use predictive simulation for pre-emptive response to inundation of farmland. In this paper, a case of immersion analysis simulation using a GIS(Geospatial Information System) based SWMM model was introduced, and the validity was confirmed through the error rate between our simulation result and the results of other models in the US and Korea. In addition, in the direction of using the simulation for agricultural land inundation, we presented various utilization methods to supplement the current agricultural land inundation-based information policy, such as the creation of flood traces. If simulation results from more regions are accumulated in the form of the flood analysis maps in the future, it is expected that they will be able to be utilized in various applications for preemptive response to and prevention of water disasters at the national level.