• 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 Environmental Science International
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• v.17 no.6
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• pp.601-609
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• 2008

In this study for the development of area due to the increasing of industry, population and spreading of urbanization is rapidly increasing but about seventy percent of our nation's areas consists of the mountainous districts. In such case, when those areas have the heavy rains break, they are washed away by a fast-flowing stream of a valley and overflowed. Thus it could result on human life and property damage and also the widespread of flood damage in the downstream area. To decrease those damage, the construction of flood control reservoir is necessary. This research was aim to construct the flood runoff models of a mountainous small district and to determine the probability rainfall by analyzing precipitation. The study also examined the effects of location and size of flood control reservoir on flood reduction. The result showed that the construction of detention basin was an effective way to ensure the safety of flood control and multiple detention basin had superior result for reducing amount of runoff in the down stream area than the single detention basin.

• Journal of Korea Water Resources Association
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• v.30 no.3
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• pp.257-268
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• 1997

Reservoir operators and managers need to present a rational basis of determining releases for a flood event. This study divides a forecasted flood hydrograph by two parts on the basis of non-damaging discharge, which consists of one part con,trolled by non-damaging discharge and another controlled by using flood control storage of the reservoir. In case of using flood control storage, a new reservoir operation method. called TRF (Transformed Reservoir Flood) ROM, is suggested for the operating rules during a flood to consider the reservoir security as well as the operational efficiency. This paper presents an application of the methodology to the operation of a single multipurpose reservoir at the Taechong Dam during flood and the results analyzed.alyzed.

• Magazine of the Korean Society of Agricultural Engineers
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• v.21 no.1
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• pp.13-23
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• 1979

The predictien of a design flood hydrograph at a particular site on a river may be based on the derivation of a discharge or stage hydrograph at an upstream section, together with a method to route this hydrograph along the rest of the river. In order to limit this investigation to cases where the assumption like uniform rainfall may be reasonably valid, the derivation of unit hydrographs has been limited to catchment with an area less than 500 km2. Consequently, flood routing methods provide a useful tool for the analysis of flooding in all but the smaller catchment, particularly where the shape of the hydrograph as well as the peak value is required. The author, therefore, will introduce here a flood routing method on the open channel with a peak discharge of the catchment area concerned. The importance of being able to route floods accurately is also reflected in the large number of flood routing method which have been developed since the year 1900. There are the modified puls method, Steinberg method, Goodrich method, Ekdahl method, Tatum's mean continuously Equation, wisler-Brater method, Muskingum, chung, and Muskingum-cunge (M-C) method and so on. The author will try to introduce a flood routing method which is revised Muskingum-cunge method. In calculating flood routing by the M-C method, whole variable parameters on the river were assumed to almost uniform values from the upstream to the downstream. In the results, the controlled flood rates at the 40km downstream on the river is appeared to decrease 22m$^3$/sec or 12 percent of the peak flood 170m$^3$/sec.

• Journal of Wetlands Research
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• v.10 no.3
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• pp.69-78
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• 2008

In recent, we have a growing interest in the washland construction for the satisfaction of flood mitigation and ecological function in the river. This study performed the flood mitigation analysis for washland construction plan in Topyoung-cheon basin in Changyeong-gun, Gyeongnam. Several cases were considered for the washland construction on Topyoung-cheon basin, and we analyzed flood stage, inundation and flood damage mitigation for each case. From the result of flood mitigation analysis, we found some significant results according to the combination of each washland case and form. Therefore, to maximize flood mitigation effect by flood mitigation analysis is more desirable than guarantee the maximum storage area in washland construction.

• Journal of The Korean Society of Agricultural Engineers
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• v.56 no.6
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• pp.103-111
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• 2014

This study was to develop the flood analysis module (FAM) for implementation of a web-based real-time agricultural flood management system. The FAM was developed to apply for an individual watershed, including agricultural reservoir. This module calculates the flood inflow hydrograph to the reservoir using effective rainfall by NRCS-CN method and unit hydrograph calculated by Clark, SCS, and Nakayasu synthetic unit hydrograph methods, and then perform the reservoir routing by modified Puls method. It was programmed to consider the automatic reservoir operation method (AutoROM) based on flood control water level of reservoir. For a $15.7km^2$ Gyeryong watershed including $472{\times}10^4m^3$ agricultural reservoir, rainfall loss, rainfall excess, peak inflow, total inflow, maximum discharge, and maximum water level for each duration time were compared between the FAM and HEC-HMS (applied SCS and Clark unit hydrograph methods). The FAM results showed entirely consistent for all components with simulated results by HEC-HMS. It means that the applied methods to the FAM were implemented properly.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2004.11a
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• pp.389-392
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• 2004

A recent unusual change in the weather is formed as a localized heavy rain in a short time. This phenomenon has caused a flash flood, and flash floods extensively have damaged human lives many times. In large river's case, the extent of loss of lives and properties has been decreased through the flood warning system by flood control stations of each stream. However, the extent of damage in other small rivers has increased reversely. Therefore, it is necessary to establish a new flood warning system against flash floods instead of the existing flood warning system. It is a specific character that the damage from flash floods in mountain streams brings much more loss of lives than large river's flood. The purpose of this study is calculating the characteristic of flash floods in streams, analyzing topographical characteristics of water basin through applying GIS techniques with the calculation as mentioned above and researching what topographical conditions have influence on hydrological flash floods in water basin. The flash flood prediction model we used is made by GIUH (geomorphoclimatic instantaneous unit hydrograph) with hydrologic-topographical technology. As applying the flash flood prediction model, this is a procedure for calculating topographical information in basin: we made a topological data up out of database with utilizing GIS, and we also produced a DEM (digital elevation model) and used it as a topographical data for determining amount of flash floods.

• Journal of the Korean Institute of Intelligent Systems
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• v.15 no.4
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• pp.437-442
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• 2005

The forecasting of flood runoff in the river is essential for flood control. The purpose of this study is to test a development of system for flood runoff forecasting using neural network model. For the flood events the tested rainfall and runoff data were the input to the input layer and the flood runoff data were used in the output layer To choose the forecasting model which would make up of runoff forecasting system properly, real-time runoff in the river when flood periods were forecasted by using the neural network model and the state-space model. A comparison of the results obtained by the two forecasting models indicated the superiority and reliability of the neural network model over the state-space model. The neural network model was modified to work in the Web and developed to be the basic model of the forecasting system for the flood runoff.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.659-663
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• 2010

In recent, flood inundation damages by hydraulic structure failures have increased drastically and thus a variety of countermeasures were needed to minimize such damages. A real-time flood inundation prediction technique is essential to protect and mitigate flood inundation damages. In the context of real time flood inundation modeling, this study aims to develop a grid based two-dimensional numerical method for flood inundation modeling using globally-available DEM data: SRTM with $90m{\times}90m$ spatial resolution. The newly-developed model guarantees computational efficiency in terms of geometric data processing by direct application of DEM for flood inundation modeling and also have good compatibility with various types of raster data when compared to a commercial model such as FLUMEN. The model, which employed the leap-frog algorithm to solve shallow water and continuity equations, can simulate inundating flow from channel to lowland and also returning flow from lowland to channel by comparing water levels between channel and lowland in real time. We applied the model to simulate the BaekSan levee break in the Nam river during a flood period from August 10 to 13, 2002. The simulation results had good agreements with the field-surveyed data in terms of inundated area and also showed physically-acceptable velocity vector maps with respect to inundating and returning flows.

• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.3
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• pp.103-111
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• 2012

Works for dam heightening plan have dual purposes: flood disaster prevention by securing additional storage volume and river ecosystem conservation by supplying stream maintenance flow. Now, the dam heightening project is in progress and there are 93 dam heightened reservoir. After the dam heightening project, 2.2 hundred million ton of flood control volume in reservoirs will be secured. Thus it is necessary to evaluate the effects of the dam heightening project on watershed hydrology and stream hydraulics, and resulting flood damages. This study was aimed to assess the impact of outflow from the dam heightened reservoir group on the Whangryong river design flood. The HEC-HMS (Hydrologic Engineering Center-Hydrologic Modeling System) model was used for estimating flood discharge, while HEC-5 (Hydrologic Engineering Center-5) was used for reservoir routing. This study analysed flood reduction effect on 100yr and 200yr return periods about the before and after heightening of agricultural dams. Based on the results of this study, the reduction of flood peak discharge at downstream of the reservoir group was estimated to be about 41% and 53% for 100yr and 200yr frequencies, respectively.