• Journal of Korea Water Resources Association
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• v.48 no.8
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• pp.605-612
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• 2015

The purpose of this study is to compare and analyze design flood estimation methods which are the basis for determining the size of a flood control structure. The result from a flood frequency analysis which is considered as the best way for estimating design flood was assumed as a true value, and a method of simulating runoff and performing frequency analysis of the maximum discharge data were compared with a design storm method. For a comparative analysis of design flood estimation, seven basins (Namgang reservoir basin, Soyanggang reservoir basin, Andong reservoir basin, Seomjingang reservoir basin, Imha reservoir basin, Chungju reservoir basin, Hapcheon reservoir basin) were selected. For the Seomjingang, Hapcheon, and Imha reservoir basins, the method proposed in this study showed better results, whereas the conventional method showed better results for the Namgang, Soyanggang, and Chungju reservoir basins. The results show that the conventional method (the design storm method) is not the best way for estimating design flood and the proposed method can be used as an alternative for small basins.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.5B
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• pp.511-517
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• 2006

Flood damage is one of the most important and influential natural disaster which has an effect on human beings. Local concentrated heavy rainfall in urban area yields flood damage increase due to insufficient capacity of drainage system. When the excessive flood occurs in urban area, it yields huge property losses of public facilities involving roadway inundation to paralyze industrial and transportation system of the city. To prevent such flood damages in urban area, it is necessary to develop adequate inundation analysis model which can consider complicated geometry of urban area and artificial drainage system simultaneously. In this study, an urban flood analysis model adopting the unstructured computational grid was developed to simulate the urban flood characteristics such as inundation area, depth and integrated with subsurface drainage network systems. By the result, we can make use of these presented method to find a flood hazard area and to make a flodd evacuation map. The model can also establish flood-mitigation measures as a part of the decision support system for flood control authority.

• Proceedings of the KSR Conference
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• 2004.06a
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• pp.224-228
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• 2004

In these days, as it frequently happens that water level in the river exceeds the design floods due to irregular heavy rainfall, so it is required, first of an, to manage with railroad bridge safely. Because train control criterion under heavy rainfall is still not prepared and automatic flood monitoring system for railroad bridges is not used, worry over invisible economic loss due to train passage delay is in existence. Therefore, it is important to secure the safety and detect the risk like turnover or failure of railroad bridges through systematic disaster prevention system. And the transition from conventional monitoring method to real time monitoring method supported by sensors and communication system with high technology is rapidly needed. This research is on developing the real time flood monitoring system which prevents railroad disasters in advance by detecting continuously the water level of railroad bridge through CCD camera and water level gauge.

• Journal of Korea Water Resources Association
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• v.37 no.12
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• pp.1043-1054
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• 2004

An unsteady flow model for channel network including various internal boundaries if developed. It is a multiply-connected network model based on the Preissmann's four-point scheme and the Newton-Raphson method, where looped double-sweep algorithm is used. The model is capable of simulating flow through hydraulic structures such as dams and submerged weirs. It can also simulate automatic reservoir operation method (Auto ROM) for flood control, that is to maintain a target water level, by incorporating the strategy to the unsteady flow model as internal boundary condition. The model is applied to the Han River system that includes the downstream reaches of Choongju dam and Hwacheon dam as well as the downstream reach of the Paldang dam. Roughness coefficient for the downstream reach of Choongju dam is estimated. Automatic ROM is presumed for the Paldang, Chungpyung, Euiam, and Choonchun dams. The model is tested using historical flood records, and the flood control strategy is successfully simulated.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1B
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• pp.27-38
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• 2006

The storage function model (SFM) has been used for the flood forecasting in Korea. The SFM has a simple calculation process and it is known that the model is more reasonable than linear model because it considers non-linearity of flood runoff. However, the determination of parameters is very difficult. In general, the trial and error method which is an manual calibration by the decision of a model manager. This study calibrated the parameters by the trial and error method and optimization technique. The calibrated parameters were compared with the representative parameters which are used in the Flood Control Centers in Korea. Also, the evaluation indexes on objective functions and calibration methods for the comparative analysis of simulation efficiency. As a result, the Genetic Algorithm showed the smallest variation in objective functions and, in this study, it is known that the objective function of SSR (Sum of Squared of Residual) is the best one for the flood forecasting.

• Journal of Environmental Impact Assessment
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• v.16 no.3
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• pp.187-194
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• 2007

It started road constructions around river in 1990s. These maintenances concentrate on city river. Because river lives no living things and men don't come near there. But in spite of these river environment go to rack, river maintenances still keep on using preexistence method since 1990s. Only a part of city river environment maintenances consider environmental ability of passive river, river maintenance of a purpose of flood control still don't consider in the concrete. Because propulsion device that consider environment ability of passive river and possible application techniques don't complete. In accordance, A natural river maintenance needs absolutly a series of river projects. Because a natural river maintenance prevents a damage of environment ability. This study is to assume the flood really happened and to carry out the flood damage simulation needed in overflow simulation about the inundated zone. Also, This study examine unstable part about the hydraulic characteristic as velocities, stream power, shear, hydraulic depth, flow area in basin. And this study applied the HEC-RAS(river analysis system) model to predict flood overflow in youngsan river basin. Project flood is used the return period 100 year and inputed data that was calculated in intensity figures of illumination.

• Journal of Korea Water Resources Association
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• v.45 no.10
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• pp.1035-1041
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• 2012

This paper is on the decision of design magnitude for flood control of urban basin, based on flooding characteristic values. In Korea, a design magnitude for flood control is established based on peak discharge of the outlet of basin. However, this method is inappropriate in an urban basin because sewerage only can flow out as much as it could and other discharge overflow to basin. In order to calculate a design magnitude for flood control of an urban basin, flooding characteristic values (peak discharge of pipe, average flooded depth, maximum flooded depths of an important point, flooded area, flooded volume, flooded time) were used as a tool. Using the Gwanghwamun Square as an example, a methodology was proposed that used XP-SWMM 2010 model as a platform to predict urban flood disaster. It can help other local government and residents to better understand, prepare for and manage a flood in urban environments.

• Water for future
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• v.28 no.3
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• pp.187-195
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• 1995

This study aims at suggesting an alternative to improve current capacity of flood control for the existing Soyanggang multi-purpose dam which was constructed 20 years ago as a largest dam in Korea. The newly estimated value of the probable maximum precipitation(PMP) is 760.0 mm which is based on the hydrometeorological method. The peak inflow of 1000 years return period at the time of construction was 13,500$m^3$/s. However, the newly estimated peak inflow of the PMF is 18,100$m^3$/s which is 1.34 times bigger than the original one. In order to adopt the newly estimated PMF as a design flood, following four alternatives were compared; (1) allocation of more flood control space by lowering the normal high water level, (2) construction of a new spillway in addition to the existing one, (3) raising the existing dam crest, (4) construction of a new dam which has relevant flood control storage at the upstream of the Soyanggang multipurpose dam. The preliminary evaluation of these alternatives resulted in that the second alternative is most economical and feasible. So as to stably cope with the newly estimated PMF by meeting all the current functions of the multi-purpose dam, a detailed study of an additional spillway tunnel has to be followed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1B
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• pp.39-50
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• 2006

The flood control offices of main rivers have used a storage function model to forecast flood stage in Korea and studies of flood forecasting actively have been done even now. On this account, the storage function model, which is used in flood control office, regression models and artificial neural network model are applied into flood forecasting of study watershed in this paper. The result obtained by each method are analyzed for the comparative study. In case of storage function model, this paper uses the representative parameters of the flood control offices and the optimized parameters. Regression coefficients are obtained by regression analysis and neural network is trained by backpropagation algorithm after selecting four events between 1995 to 2001. As a result of this study, it is shown that the optimized parameters are superior to the representative parameters for flood forecasting. The results obtained by multiple, robust, stepwise regression analysis, one of the regression methods, show very good forecasts. Although the artificial neural network model shows less exact results than the regression model, it can be efficient way to produce a good forecasts.

• 한국방재학회:학술대회논문집
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• 2009.02b
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• pp.144.2-144.2
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• 2009