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

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.43 no.6
• /
• pp.735-747
• /
• 2023

In recent times, the sharp increase in extreme flood damages due to climate change has posed a challenge to effectively address flood-related issues solely relying on conventional flood management infrastructure. In response to this problem, this study aims to consider the effectiveness of nature-based flood management approaches, specifically levee retreat and relocation. To achieve this, we utilized a 1D numerical model, HEC-RAS, to analyze the flood reduction effects concerning floodwater levels, flow velocities, and time-dependent responses to a 100-year frequency flood event. The analysis results revealed that the effect of creating a flood buffer zone of the nature-based solution extends from upstream to downstream, reducing flood water levels by up to 30 cm. The selection of the flow roughness coefficient in consideration of the nature-based flood buffer space creation characteristics should be based on precise criteria and scientific evidence because it is sensitive to the flood control effect analysis results. Notably, floodwater levels increased in some expanded floodplain sections, and the reduction in flow velocities varied depending on the ratio of the expanded cross-sectional area. In conclusion, levee retreat and floodplain expansion are viable nature-based alternatives for effective flood management. However, a comprehensive design approach is essential considering flood control effects, flow velocity reduction, and the timing of peak water levels. This study offers insights into addressing the challenges of climate-induced extreme flooding and advancing flood management strategies.

• Water for future
• /
• v.29 no.1
• /
• pp.163-179
• /
• 1996

Flood flow characteristics of the Han River (from Goan to Indo Bridge) are analyzed using 1-dimensional St. Venant equations. NETWORK, a finite difference model, is used to calculate each term (local acceleration term, convective acceleration term, pressure force term, gravity force term, and friction force term) of the momentum equation and to analyze the flow characteristics. By the result of the study, as the general characteristics of flow in a channel that acceleration terms are very small and the other three terms are much greater is presented, three terms(pressure force term, gravity force term, friction force term) are to be main terms which decide the characteristics of flow. Specially in this region the acceleration term is noted so large that it cannot be ignored according to the shape of hydrograph and the region.

• Journal of Korea Water Resources Association
• /
• v.46 no.7
• /
• pp.767-781
• /
• 2013

In this study, the hydraulic model experiments and numerical simulations are carried out to analyze the flood flow characteristics in and around a channel confluence connected asymmetrically with four channels. The numerical model applied in this study is ANSYS CFX (ver. 14) which is the commercial three-dimensional CFD model. As results of comparison between the measured and simulated water depth distributions in and around a channel confluence, the agreement is relatively well satisfied. It can be shown in this study that the water surface profiles in and around a channel confluence are significant different with the two channel directions in which the water are entering and increased inflow.

• Journal of Wetlands Research
• /
• v.18 no.4
• /
• pp.413-423
• /
• 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 the Korean Society of Industry Convergence
• /
• v.4 no.1
• /
• pp.51-60
• /
• 2001

This study examines the effects of removal of the sediment protection weir at Taehwa river mouth on hydraulic and around river environment considering the fact that the effects of the sediment protection weir which is installed to protect water level drop of Ulsan harbor caused by sediments according to flood in Taehwa river, Dong-chun, and so forth may add water quality contamination by flow stagnance in normal and drought period and accumulation of pollutants. The result is as follows. First, it is estimated from the examination of variation characteristics water depth and level for Taehwa river before and after removal of the sediment protection weir that about 0.01m of water depth down according to removal of the sediment protection weir occurs when low flow runs between the sediment protection weir which is located about 2.3km away from the estuary and Samho-gyo which is about 9.0km away from the sediment protection weir, and about 0.01~0.56m(directly upstream point of the sediment protection weir 0.56m, Myongchon-gyo 0.14m, Ulsan-gyo 0.03m, and Taehwa-gyo 0.02m) downs when design flood flows between the sediment protection weir and the upstream of Taehwa-gyo which is 10km away from the sediment protection weir. Therefore, it is thought that variation of hydraulic characteristics of water depth down and so on according to removal of the sediment protection weir is slight because water depth variation is only about 1cm between directly upstream point of the sediment protection weir and Samho-gyo. Next, it is estimated from the examination of variation characteristics of flow velocity for Taehwa river before and after removal of the sediment protection weir that about 0.0lm/s of flow velocity increase occurs between the directly upstream point of the sediment protection weir which is about 2.4km away from the estuary and the directly upstream point of Samho-gyo when low flow runs, and about 0.01~0.44m/s increases between the sediment protection weir and Samho-gyo when design flood flows. Therefore, riverbed erosion by the increased flow velocity is concerned but it is thought that the concern about riverbed erosion is not great because the mean velocity is about 0.07~1.36m/s when low flow runs, and about 1.02~2.41m/s when design flood flows for the sector which experiences the flow velocity variation.

• 한국방재학회:학술대회논문집
• /
• 2007.02a
• /
• pp.267-270
• /
• 2007

In order to reduce flood damage with debris flow, it is necessary to build up comprehensive flood control, including structural and non-structural countermeasures. In this paper, the decision making factors of individual refuge activities which are major non-structural activities to save peoples, lives against flood have been estimated based on questionnaire survey. Furthermore, in order to effective debris flow countermeasures, its simulation has carried out and it will useful for minimizing their damages.

• Spatial Information Research
• /
• v.16 no.1
• /
• pp.11-17
• /
• 2008

In order to reduce flood damage with debris flow, it is necessary to build up comprehensive flood control, including structural and non-structural countermeasures. In this paper, the decision making factors of individual refuge activities which are major non-structural activities to save peoples, lives against flood have been estimated based on questionnaire survey. Furthermore, in order to effective debris flow countermeasures, its simulation has carried out and it will useful fur minimizing their damages.

• 한국방재학회:학술대회논문집
• /
• 2008.02a
• /
• pp.707-710
• /
• 2008

Recently, a rivers' bridge that locate on among the mountains area is destroyed by debris accumulation and debris flow, because of frequent occurrence of typhoon and a localized torrential downpour. therefore a river make a part of dam's effect. Actually, this situation gives damages like inundation of a bridge upper stream area's. Generally, It the main cause of the occurrence route of the debris accumulation is that outbreaks of driftwood and debris flow because of landslide, that occurred by severe rain storm. Also, a lot of debris are occurred when big flood come up during long period at this time, this kind of debris accumulation remove to other place, in several, and specially, debris accumlation move to the place where the depth of water is deep and velocity is fast river center. According to these kind of fact, this research put in effect and analyze that movement characteristic's numerical simulations of debris accumulation at flood according to a domestic outside literature investigation, on-site monitoring survey and parameter scenario which comes out through the hydraulic modeling analysis.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2004.05b
• /
• pp.908-911
• /
• 2004

The purpose of this study is to investigate the applicability of the two dimensional model in natural rivers. In this study, two dimensional unite element model, SMS, is used to simulate a complex flow along with the sediment movements in the natural river. The RMA-2 model embeded in SMS is used to simulate flow phenomena and SED-2D model is employed to simulate sediment transport. The model is applied to the confluence zone of the Gam River and mouth of Nakdong River. For model calibration, the result of the unsteady flow analysis is compared with the Typhoon 'Rusa' data. In addition, the runoff analysis was conducted for the determination of the project flood and the flood forecasting. The simulation results presented the characteristics of two dimensional flow with velocity vector and flow depth. The sediment transport characteristics are shown in terms of sediment concentration as well as bed elevation change. Accordingly, the SMS model in this study turned out to be very effective tool for the simulation of the hydrodynamic characteristics under the various flow conditions and corresponding sediment transports in natural rivers.