• The Journal of the Korea Contents Association
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• v.10 no.11
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• pp.452-460
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• 2010

This study carried out stability evaluation for design flood stage of vegetation models with river sites using 1D HEC-RAS and 2D RMA-2 numerical models. The vegetation models established in this study were divided into which channel reaches consist of urban, rural and mountain rivers with the social and cultural significance of the sites. Examination results from the numerical models showed a similar aspect with the design flood stage of these rivers before vegetation modeling. Also, no embankment overflow was shown from the urban river with additional vegetation density of 25%, although there were approximately 0.20m rising in the flood stage. In case of ural and mountain rivers, vegetation models showed scarce rising in flood stage.

• Journal of Wetlands Research
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• v.18 no.4
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• pp.413-423
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• 2016

Effects of the design flood share of the Kyeongpo retarding basin, which has a function for flood control of the Kyeongpo river assigned to the Kyeongpo prickly water lily wetland, on the Kyeongpo lake and the downstream of Kyeongpo river were analyzed on the bassis of the hydraulic experiments and the numerical simulations using RMA-2 model. Reproducing a complex water flow system of the area of Kyeongpo lake, the unsteady flow simulations were performed. The data obtained in hydraulic experiments were used to determine parameters of the numerical model which simulated the flows for various flood scenarios in the downstream area of Kyeongpo river. With increasing the design flood share rates in the retarding basin, the water level was increased in the lake and is decreased in the river. The characteristics of flood flow interaction between Kyeongpo river and Kyeongpo lake were understood. These results may be used to management the Kyeongpo lake during flood season.

• Journal of Environmental Science International
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• v.25 no.9
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• pp.1253-1267
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• 2016

After large-scale flooding damage occurred along the Imjin river in 1996, 1998, and 1999, the Hantan river flood control dam was planned, and it has since been under construction. Unlike existing dams in Korea, the Hantan river flood control dam will remain fully open except during high floods, when the dam will store flood water temporarily to reduce flood peaks and flood water volume downstream. During past flooding seasons, floating debris has caused difficulties in the management of large-scale dams. Most of the existing multipurpose dams in Korea have installed nets to collect floating debris based on many years of experience with and data about inflow and distribution of floating debris in the dams. For the Hantan river flood control dam, however, collection of data about inflow and distribution of floating debris is not possible as the dam is located near the border area between North and South Korea. In order to devise a preliminary plan to collect floating debris in the Hantan river flood control dam, an EFDC hydrodynamic model was used to analyze the behavior of floating debris during high floods. The Lagrangian particle tracking method was utilized to simulate the behavior of floating debris in the dam. Based on the analysis of paths and final destinations of the particles, seven collection points were selected where it seemed to be effective to collect floating debris, as debris is likely to accumulate there in high density.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.1182-1186
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• 2006

The decision of design flood in river basins is very important in the aspect of flood control. The design flood of rivers was estimated according to the size and importance of basins. As the damage of floods increases more and more and the importance of defense against floods increases further, the presumption of design flood can be very important. Especially, what influences most greatly flood is rainfall. However, in spite of equal rainfall, the estimated flood differ according to the features of basins. The fact that the features of basins influence greatly the estimation of flood was confirmed by the preceding research results and experiences. However, although many rivers have their own basin features, the research on how these basin features are related to the estimation of design flood, is not yet sufficient. The purpose of this study is to identify how the design flood estimated previously by river arrangement basic plan is correlated with topography factors, and so investigate the correlation between basin topography factors and design flood in order to provide the additional information for the unmeasured basins or the middle/small river basins where their river plan is not established.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.158-158
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• 2019

Recent studies show the possibility of more frequent extreme events as a result of the changing climate. These weather extremes, such as excessive rainfall, result to debris flow, river overflow and urban flooding, which post a substantial threat to the community. Therefore, an effective flood model is a crucial tool in flood disaster mitigation. In recent years, a number of flood models has been established; however, the major challenge in developing effective and accurate inundation models is the inconvenience of running multiple models for separate conditions. Among the solutions in recent researches is the development of the combined 1D-2D flood modeling. The coupled 1D-2D river flood modeling allows channel flows to be represented in 1D and the overbank flow to be modeled over two-dimension. To test the efficiency of this approach, this research aims to assess the capability of HEC-RAS model's implementation of the combined 1D-2D hydraulic simulation of river overflow inundation, and compare with the results of GERIS and FLUMENS 2D flood model. Results show similar output to the flood models that had used different methods. This proves the applicability of the HEC-RAS 1D-2D coupling method as a powerful tool in simulating accurate inundation for flood events.

• Journal of the Korean Association of Geographic Information Studies
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• v.12 no.1
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• pp.1-11
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• 2009

Rapid visualization of flood area of downstream according to the dam effluent in flood season is very important in dam management works. Overlay zone of river bight should be removed to represent flood area efficiently based on flood stage which was modeled in river channels. This study applied drainage enforcement algorithm to visualize flood area considering river bight by coupling Coordinate Operation System for Flood control In Multi-reservoir (COSFIM) and Flood Wave routing model (FLDWAV). The drainage enforcement algorithm is a kind of interpolation which gives to advantage into hydrological process studies by removing spurious sinks of terrain in automatic drainage algorithm. This study presented mapping technique of flood area layer considering river bight in Namgang-Dam downstream, and developed system based on Arcobject component to execute this process automatically. Automatic extraction system of flood area layer could save time-consuming efficiently in flood inundation visualization work which was propelled based on large volume data. Also, flood area layer by coupling with IKONOS satellite image presented real information in flood disaster works.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.918-922
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• 2006

The purpose of this study is development of operation model for flood control of multi-reservoir in river basin, which can provide the best decision of reservoir release in timely and appropriately manner using CSUDP. For verification and validation of the developed system, the Gum River Basin was selected, which has 82 rainfall gauging stations, 28 water level gauging and 2 multi-purpose reservoirs which can control flood. There was a successful simulation of the developed model and system, using the real-time data from the Han River Basin Flood Forecast Center. Specially, case study for '1995 flood was performed.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1999.10c
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• pp.454-458
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• 1999

This study is to analyze the causes of flood damage in Imjin river basin inAugust , 1999. and to propose the measure to reudce such flood damage. The northern part of Kyonggin Province in the basin was severely damaged by flood due to the heavy rainfall for 4 days from 31 July to 3 August, whioch was recordedas 1,032mm. The heavy rainfall worth recording was one of main cuasese of such damage, but unsuitable river improvement and basin management were also important causes. The flood proptection works such as flood control reservoir and riverlevee were not contructed or sufficient in spite of the unflavorable geographical conditions of Imjin reiver. In case of irrigatiion faciliteis, 43 pumping stations in 3 FIAs were severely damaged due to inundation of the pump and switch boxes. The protection works for pump room should be improved to reduce the damage due to inundation.

• Journal of Wetlands Research
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• v.4 no.1
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• pp.43-50
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• 2002

The channel improvement plan has contributed to the flood damage reduction studies and the plan has mainly performed by the levee construction which creates the cut river. The cut river has mainly used as the agricultural and housing purposes. Recently, however, it is considered as a natural wetland for the purposes of a flood control and preservation of nature. So, this study compares the economical benefits according to the purposes of the cut river utilizations such as an agricultural, levee construction for flood damage reduction, and wetland. The study area is the downstream part of Kok-Neung stream which is a main tributary of Han river. The agricultural and levee construction benefits are estimated based on the 'Agricultural and Forestry Statistical Year' (2000) and the 'Standard for River Design' (2001). The benefit or value for the wetland utilization of the cut river is estimated by the enquete using questionnaire. As a results, for the case of which the cut river is used as an agricultural land, the present net benefit is estimated as 195.81 million won, for the levee construction, as 20853.00 million won and for the wetland, as 24692.89 million won. Therefore, the wetland is the best choice for the cut river utilization.

• Journal of The Korean Society of Agricultural Engineers
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• v.58 no.5
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• pp.11-18
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• 2016

The objective of this study was to develop the simple method to estimate ungauged river section for flood stage analysis. Damage prediction should be prioritized using hydrological modeling to reduce flood risk. Mostly, the geographical data using hydrological modeling depends on national river cross-section survey. However because of the lack of measured data, it is difficult to apply to many local streams or small watersheds. For this reason, this study suggest the method to estimate unguaged river cross-section. Simple regression equations were derived and used to estimate river cross-section by analyzing the correlation between the river cross-sectional characteristics (width, height and area). The estimated cross-sections were used to simulate flood level by HEC-RAS (Hydrologic Engineering Center's River Analysis System). The applicability of this method was verified by comparing simulated flood level between measured and estimated cross-section. The water surface elevation of the flood stage analysis was 6.56-7.24 m, 5.33-5.95 m and 6.12-6.75 m for measured cross section, for estimated cross section and for estimated cross section based on DEM elevation, respectively. Further study should consider other factors for more accurate flood stage analysis. This study might be used one of the guidelines to estimate ungauged river section for flood stage analysis.