• Journal of Korea Water Resources Association
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• v.40 no.1 s.174
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• pp.1-10
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• 2007

Reallocation procedure of multipurpose reservoir storage capacity between flood control and conservation is presented as an alternative to secure more water resources. Storage reallocation is an adaptive management mechanism for converting existing normal pool level of reservoirs to more beneficial uses without requirement for physical alteration. This study is intended to develop a reservoir storage reallocation methodology that allows increased water supply storage without minimizing adverse impacts on flood control. The methodology consists of flood control reservoir simulation for inflows with various return periods, flow routing from reservoir to a potential damage site, analyzing river carrying capacity, and reservoir yields estimation for reallocated storages. For the flood control model, a simulation model called Rigid ROM(Reservoir Operation Method) and HEC-5 are used. The approach is illustrated by applying it to two reservoirs system in Geum River basin. Especially with and without new project conditions are considered to analyze trade-offs between competing objectives.

• Journal of Korea Water Resources Association
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• v.41 no.9
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• pp.929-941
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• 2008

The objectives of this study are to propose a system for combined use of a hydrologic and a hydraulic model for urban flood forecast model and to evaluate the system on the $300km^2$ Jungrang urban watershed area, which is relatively large area as an urban watershed and consequently composed of very complex drainage pipes and streams with different land uses. In this study, SWMM for hydrologic model and HEC-RAS for hydraulic model are used and the study area is divided into 25 subbasins. The SWMM model is used for sewer drainage analysis within each subbasin, while HEC-RAS for unstready flow analysis in the channel streams. Also, this study develops a GUI system composed of mean areal precipitation input component, hydrologic runoff analysis component, stream channel routing component, and graphical representation of model output. The proposed system was calibrated for the model parameters and verified for the model applicability by using the observation data. The correlation coefficients between simulated and observed flows at the 2 important locations were ranged on 0.83-0.98, while the coefficients of model efficiency on 0.60-0.92 for the verification periods. This study also provided the possibilities of manhole overflows and channel bank inundation through the calculated water profile of longitudinal and channel sections, respectively. It can be concluded that the proposed system can be used as a surface runoff and channel routing models for urban flood forecast over the large watershed area.

• Magazine of the Korean Society of Agricultural Engineers
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• v.36 no.3
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• pp.67-73
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• 1994

This paper is to validate the proposed models for the real-time forecasting for the Keum river estuary dam such as tidal-level forecasting model, one-dimensional unsteady flood routing model, and Kalman filter models. The tidal-level forecasting model was based on semi-range and phase lag of four tidal constituents. The dynamic wave routing model was based on an implicit finite difference solution of the complete one-dimensional St. Venant equations of unsteady flow. The Kalman filter model was composed of a processing equation and adaptive filtering algorithm. The processng equations are second ordpr autoregressive model and autoregressive moving average model. Simulated results of the models were compared with field data and were reviewed.

• Korean Journal of Hydrosciences
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• v.6
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• pp.81-98
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• 1995

A linear reservoir rainfall-runoff system was developed as a rainfall-runoff event simulation model. It was achieved from large modification of runoff function method. There are six parameters in the model. Hydrologic losses consist of some quantity of initial loss and some ratio of rainfall intensity followed by initial loss. The model has analytical routing equations. Hooke and Jaeves algorithm was used for model calibration. Parameters were estimated for flood events from '84 to '89 at Seomyeon and Munmak stream gauges, and the trends of major parameters were analyzed. Using the trends, verifications were performed for the flood event in September 1990. Because antecedent rainfalls affect initial loss, future researches are required on such effects. The estimation method of major parameters should also be studied for real-time forecasting.

• Magazine of the Korean Society of Agricultural Engineers
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• v.20 no.3
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• pp.4724-4731
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• 1978

Using hydrometric data from an upland river in North Wales, a relationship between rate of river flow and water stored within the catchment area (catchment storage) is assumed to exist, and is evaluated from an analysis of winter recession curves. This storage/river flow relationship, when combined with water balance equations, produces a set of equations which may be used for "routing" input of rainfall through a storage with defined outflow characteristics, providing a straightforward method of flood prediction and analysis from rainfall data. Recorded and predicted flood hydrographs are compared, and the effectiveness and limitations of the method are considered. The development of a complete mathematical model, embodying the storage/river flow relationship, and suitable for generation of continuous run-off records from rainfall and evaporation data, is also considered.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.2
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• pp.537-548
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• 2013

In this study, the hydraulic channel routing model was constructed to analysis the effect of flood control with the operation of Chungju Dam for 2006 flood. Study area was divided with up- and downstream of Chungju Dam in the upper Han River of Paldang Dam. The model was calibrated and verified for the flood event of 1995-2008. The effects of flood control of Chungju Dam were compared with the simulation results without the dam, and the rising effects of stage in the main observation stations were analyzed by the variation of released dam discharge. Consequently, the operation of Chungju Dam for 2006 flood was performed properly, but the effects of flood control of Chungju Dam were so focused in downstream of the dam that institutional complement was demanded to reduce the flood damage in the upper region of the dam. The limit of decision rule of downstream stage in the backwater region of dam was analyzed to solve the problem, and the decision rule of downstream stage was proposed to consider the discontinuity between the backwater region of dam and the design flood of upper stream. The proposed rule will be used to design the reduction of flood damage in upper stream of dam and to apply the analysis of region for flood damage.

• Journal of Korea Water Resources Association
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• v.33 no.6
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• pp.689-699
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• 2000

This paper presents the integrated storage function model (ISFM) to improve the accuracy of the storage function model (SFM) which is widely employed for flood runoff analysis and its forecasting in Korea. In order to achieve this objective, the optimization method is applied for estimation of parameters of the model which dominate the accuracy of the analysis, which is usually taken by empirical formulae, and they are treated as time dependent variables. The fuzzy control technique is used to detennine the time variant parameters. In addition, the ISFM can be applied to the combined routing of the watershed and the channel with a residual watershed.ershed.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.1666-1670
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• 2006

The purpose of this study is to analyze how a downstream channel is affected in case of hypothetical dam failure. The object of it is Hwacheon dam basin within the basin of North Han river. This study has analyzed the influence on Pyeonghwa(Peace) dam and Hwacheon dam supposing that the Imnam dam in North Korea on the upper stream of North Han river is failed hypothetically at the MFWL(maximum flood water level) by a deluge of rain. The model applied at the main study is NWS(National Weather Service) FLDWAV(Flood Wave Routing Model). Dam breach characteristics data are analyzed by making nine hypothetical scenarios on the basis of other studies on the shape and size of dam breach, time of failure and so on. Expected peak discharge through the breach is verified to have the propriety in comparison with empirical function which is developed on the basis of the case of dam breach in the foreign countries and it is observed that peak discharge is more increasing, as the time of breach gets shorter and the breach width gets bigger. As a result of main study, even though the Imnam dam is hypothetically failed down, there has no influence on the Hwacheon dam of the downstream as the extended Pyeonghwa dam on the downstream controls the volume of discharge properly.

• Journal of Korean Society on Water Environment
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• v.21 no.6
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• pp.682-686
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• 2005

Recently some urban areas have been flooded due to heavy storm rainfalls. Though major causes of these floodings may be attributed to localized heavy rainfalls, other factors are related to urban flooding including deficiency of storm sewer network capacity, change of surface runoff due to covered open channels, and operational problems of storm drainage pump stations. In this study, hydrologic and hydraulic analysis of Sutak basin in Guri city were carried out to evaluate flooding problems occurred during the heavy storm in July, 2001. ArcView, a world most widely used GIS tool, was used to extract required data for the hydrologic analysis including basin characteristics data, concentration times, channel routing data, land use data, soil distribution data and SCS runoff curve number generation from digital maps. HEC-HMS, a GIS-based runoff simulation model, was successfully used to simulate the flood inflow hydrograph to Sutak pumping station.

• Water for future
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• v.29 no.1
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• pp.151-161
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• 1996

The proposed flood forecasting system combines a flood routing model with a parameter estimation model. In the parameter estimation model system states and parameters are treated with the extended state-space formulation. The extended Kalman filter is adopted to estimate the states and parameters. A sensitivity analysis is used to investigate the relative significance of the parameters. Insensitive parameters are treated as constants and parameters that are mutually correlated are combined in a simplified form. The developed estimation methodology is applied todam sites of the multi-purpose reservoirs in Korea. The forecasted hydrographs from the extended Kalman filter satisfactorily coincide with the observed. From the time sequence plots of estimated parameters, it is found that the storage coefficient is almost constant, but exponent varies appreciably in time.