• Journal of the Korean GEO-environmental Society
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• v.15 no.1
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• pp.69-77
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• 2014

The objective of this study is to compare flood inundation models for small stream basin. HEC-RAS model was used for the analysis of one dimensional hydraulics and HEC-GeoRAS, Ras Mapper and RiverCAD models were applied for the flood inundation analysis in Gum Chung stream. Flood inundations are to simulate by flood inundation models using observed data and rainfall on each frequency and to compare with inundation area based on the flood plain maps. The results of this study are as follows; Area of flood inundations by HEC-GeoRAS model is similar to that of flood plain map and appears in order of RAS Mapper and RiverCAD model. Flood inundation area by RiverCAD model is to estimate lager than that of RAS Mapper and HEC-GeoRAS model in flood area on each frequency and the results show that they have a little difference in models of flood inundation analysis at small stream. Comparing the area of flood inundations by flood depth, the results of three models are relatively similar in flood depth as 2.0 m below, and RiverCAD model shows a significant difference in flood depth as 2.0 m or more.

• Journal of the Korean Association of Geographic Information Studies
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• v.18 no.2
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• pp.1-15
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• 2015

Urban flooding threatens human beings and facilities with chemical and physical hazards since the beginning of human civilization. Recent studies have emphasized the integration of data and models for effective urban flood inundation modeling. However, the model set-up process is tend to be time consuming and to require a high level of data processing skill. Furthermore, in spite of the use of high resolution grid data, inundation depth and velocity are varied with building treatment methods in 2-D inundation model, because undesirable grids are generated and resulted in the reliability decline of the simulation results. Thus, it requires building generalization process or enhancing building orthogonality to minimize the distortion of building before converting building footprint into grid data. This study aims to develop building generalization method for 2-dimensional inundation analysis to enhance the model reliability, and to investigate the effect of building generalization method on urban inundation in terms of geographical engineering and hydraulic engineering. As a result to improve the reliability of 2-dimensional inundation analysis, the building generalization method developed in this study should be adapted using Digital Building Model(DBM) before model implementation in urban area. The proposed building generalization sequence was aggregation-simplification, and the threshold of the each method should be determined by considering spatial characteristics, which should not exceed the summation of building gap average and standard deviation.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.396-396
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• 2015

Frequent urban floods affect the human safety and economic properties due to a lack of the capacity of drainage system and the increased frequency of torrential rainfall. The drainage system has played an important role in flooding control, so it is necessary to establish the effective countermeasures considering the connection between drainage system and surface flow. To consider the connection, we selected SWMM5 model for analyzing transportation capacity of drainage system and FLUMEN model for calculating inundation depth and time variation of inundation area. First, Thiessen method is used to delineate the sub-catchments effectively base on drainage network data in SWMM5. Then, the output data of SWMM5, hydrograph of each manhole, were used to simulate FLUMEN to obtain inundation depth and time variation of inundation area. The proposed method is applied to Sadang area for the event occurred in $27^{th}$ of July, 2011. A total of 11 manholes, we could check the overflow from the manholes during that event as a result of the SWMM5 simulation. After that, FLUMEN was utilized to simulate overland flow using the overflow discharge to calculate inundation depth and area on ground surface. The simulated results showed reasonable agreements with observed data. Through the simulations, we confirmed that the main reason of the inundation was the insufficient transportation capacities of drainage system. Therefore cooperation of both models can be used for not only estimating inundation damages in urban areas but also for providing the theoretical supports of the urban network reconstruction. As a future works, it is recommended to decide optimized pipe diameters for efficient urban inundation simulations.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.6B
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• pp.605-612
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• 2006

In this study(II), The developed rainfall forecast model was applied to the NakDong River Basin for the heavy rainfall on 6th to 16th of August in 2002. The results demonstrated that the rainfall forecasts of 3 hours lead time showed good agreement with observed data. The inundation aspect of simulation depends on actual levee failure in the same basin. Rainfall forecasts were used for flood amount computation in the target watershed. Also the flood amount in the target watershed was used on boundary condition for flood inundation simulation in a protected lowland and a river. The results of simulation are consistent with actuality inundation traces and flood level data of the target watershed. This study provides practical applicability of satellite data in rainfall forecast of extreme events such as heavy rainfall or typhoon. Also this study presented an advanced integrated model of rainfall, runoff, and inundation analysis which can be applicable for flood disaster prevention and mitigation.

• Korean Journal of Agricultural Science
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• v.47 no.3
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• pp.509-517
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• 2020

Geographic information system (GIS) sewer network data are a fundamental input material for urban inundation modeling, which is important to reduce the increasing damages from urban inundation due to climate change. However, the essential attributes of the data built by a local government are often missing because the purpose of building the data is the maintenance of the sewer system. Inconsistent simplification and supplementation of the sewer network data made by individual researchers may increase the uncertainty of flood simulations and influence the inundation analysis results. Therefore, it is necessary to develop a basic algorithm to convert the GIS-based sewage network data into input data that can be used for inundation simulations in consistent way. In this study, the format of GIS-based sewer network data for a watershed near the Sadang Station in Seoul and the Oncheon River Basin in Busan was investigated, and a missing data supplementing algorithm was developed. The missing data such as diameter, location, elevation of pipes and manholes were assumed following a consistent rule, which was developed referring to government documents, previous studies, and average data. The developed algorithm will contribute to minimizing the uncertainty of sewer network data in an urban inundation analysis by excluding the subjective judgment of individual researchers.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.4
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• pp.105-117
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• 2010

The topographical depressions in urban areas, the lack in drainage capability, sewage backward flow, road drainage, etc. cause internal inundation, and the increase in rainfall resulting from recent climate change, the rapid urbanization accompanied by economic development and population growth, and the increase in an impervious area in urban areas deteriorate the risk of internal inundation in the urban areas. In this study, the vulnerability of internal inundation in urban areas is analyzed and SWMM model is applied into Oncheoncheon watershed, which represents urban river of Busan, as a target basin. Based on the results, the representative storm sewers in individual sub-catchments is selected and the risk of vulnerability to internal inundation due to rainfall in urban streams is analyzed. In order to analyze the risk and vulnerability of internal inundation, capacity is applied as an index indicating the volume of a storm sewer in the SWMM model, and the risk of internal inundation is into 4 steps. For the analysis on the risk of internal inundation, simulation results by using a SMMM model are compared with the actual inundation areas resulting from localized heavy rain on July 7, 2009 at Busan and comparison results are analyzed to prove the validity of the designed model. Accordingly, probabilistic rainfall at Busan was input to the model for each frequency (10, 20, 50, 100 years) and duration (6, 12, 18, 24hr) at Busan. In this study, it suggests that the findings can be used to preliminarily alarm the possibility of internal inundation and selecting the vulnerable zones in urban areas.

• Journal of the Korean Institute of Landscape Architecture
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• v.33 no.2 s.109
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• pp.71-82
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• 2005

A large scale of riverside rearrangement has been recently done in the major rivers in Korea. So inundation possibility in agricultural area closed by these rivers has been higher than the possibility a few years ago. However, land use in this area has not been adjusted to a change of this situation near the rivers. Therefore, when typhoon or heavy rain is happened on this area, it can cause a large damage in agricultural area. This study analyzed inundation potentiality in agricultural area at Ibang-myeon, Changnyeong-gun, Kyeongnam-province, Korea by using the logistic regression model and the piecewise regression model. The first thing we did was to transfer the inundation area per elevation to the accumulated inundation area per elevation. This accumulated inundation area per elevation as an distribution function could be described by the logistic regression model(LRM), and piecewise regression model(PRM) could make it much more accurate to analyze the inundation area per elevation. As a result, the regression models derived from LRM and PRM showed $R^2$ over 0.950. The models derived from LRM and PRM in Ibang-myeon noted that frequently inundated area(FIA) was shown up to 12.12m in elevation, and potentially inundated area(PIA) was shown up to 14.60m in elevation. In FIA, regular agricultural activity would be impossible. And It would be not easy to continue the regular agricultural activity in PIA. So, this land should be rearranged to be used for a buffer zone for ecosystem protection, landscape conservation and things like that in riverside.

• 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.54 no.2
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• pp.71-80
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• 2021

In recent years, the possibility of flooding due to the increase in the incidence of high-frequency rainfall due to abnormal rainfall and the increase in concentrated torrential rain is increasing. Also, the amount of rainwater runoff is increasing due to the increase of the impermeable layer in the city due to the concentration of population due to urbanization and concentration of development. Due to the characteristics of the developed city, it is located in the vicinity of rivers and in the lowlands. For the analysis of inundation in water, using XP-SWMM, which can analyze stormwater pipelines and surface flows, and FLO-2D models that can track flood-sluice curves and rainfall-spill curves, based on hydraulic and hydrological analysis. Inundation analysis was conducted and comparative review was conducted. The patterns of flooding of the two models were compared, and a model suitable for domestic flooding was selected.

• Journal of Korea Water Resources Association
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• v.36 no.4
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• pp.661-671
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• 2003

The reliability model is developed for analyzing parameter uncertainty and estimating of flood inundation characteristics in a protected lowland. The approach is based on the concept of levee safety factor and the statistical analysis of model parameters affecting the variability of flood levels. Monte Carlo simulation is incorporated into the varied flow and unsteady flow analysis to quantify the impact of parameter uncertainty on the variability of flood levels. The model is applied to a main stem of the Nakdong River from Hyunpoong to Juckpogyo station. Simulation results show that the characteristics of channel overflow and return now are well simulated and the mass conservation was satisfied. The inundation depth and area are estimated by taking into consideration of the uncertainty of width and duration time of levee failure.