• Journal of Korea Water Resources Association
• /
• v.34 no.2
• /
• pp.141-154
• /
• 2001

An experimental study was performed to investigate the effects of levee crest width and the slope steepness on levee break due to overtopping flow. The phenomenon of bank failure can be described in 4 stages. In this study, the magnitudes of breach width, breach depth peak discharge, and scouring shape at the break site were measured, and the result shows that peak discharge will be reduced and breach duration extended by widening the crown width and lessening the levee slope steepness. The breach width was narrower and the breach depth deeper, as the levee crest width become wider or the slope steeper. And, the bed scour depth was deeper and steeper, as the levee crest crest width become narrower or the slope milder.

• Journal of Korea Water Resources Association
• /
• v.42 no.7
• /
• pp.571-578
• /
• 2009

Levee-break Analysis model is developed to predict the variation of breach width according to time and to estimate inundation area and depth in protected lowland. This Model calculate flood depth using 4 point implicit finite difference method in river channel and analyze breach flow based on physical theory introducing soil transport equation and erosion process. Breach analysis model and channel flood model are combined into Levee-Break Model and this model is applied to actual levee break case. Then, this model can simulate reasonably many levee-break parameters such as river stage, breach width, breach formation and so on. If the applicability of this model is proved through applications to more various actual levee-break cases, the suggested model is expected to do more accurate flood analyses on levee break site.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.2
• /
• pp.1-8
• /
• 2018

Levee breaches can result from flooding due to torrential rainfalls, which are linked with recent abnormal climates and the aging of river levees. Breaches have caused enormous property damage and human casualties in lowland areas. Overtopping was found to be the cause for approximately 40% of all cases of breach. In this study, the reasons and mechanisms behind levee breaches were analyzed using hydraulic model testing. The overtopping stability and time delay effect of breaches were assessed for levees made with a new environmentally friendly substance. Image analysis revealed that the total breach time of the levees made with the new substance was about 2.25 times greater than that of an earthen levee. The initial breach rate of a general earthen levee was about 1.43 times higher than that of levees covered with the new substance, and the body collapsed rapidly. The breach mechanisms of levees covered with the new substance were completely different, and it is possible to prevent rapid breaches by mitigation of the breach speed on the slope by resisting overtopping.

• Water for future
• /
• v.22 no.2
• /
• pp.223-231
• /
• 1989

A dynamic levee breach model is demonstrated which can be applied to various types of breach such as overtopping, breaking, and piping. Through a hypothetical simulation the sensitivity of brach width and duration in the result are discussed. the breach width has more important effect than the failure duration upon a side discharge owing to levee breach.

• Journal of Korea Water Resources Association
• /
• v.34 no.2
• /
• pp.155-167
• /
• 2001

The effects of bank crest width, slope steepness, soil properties, and soil compactness on the characteristics of levee breach due to overlfow were investigated through a series of experiments. Generally, the major factors influencing the breach phenomenon are compactness, soil properties. crest width, and slope steepness, in that order. Using proper soil, and ensuring enough compactness in bank construction are very essential for extending breach duration and reducing peak overflow ranges for the values of breach duration, breach width, width-to-depth ratio, and side slope of the breach section, proposed by Singh, MacDonald and Fread based on the field data for earth dam breaks were reasonable. We found that those criteria could also be applied to the phenomenon of levee breaching.

• Journal of Korea Water Resources Association
• /
• v.44 no.6
• /
• pp.461-470
• /
• 2011

Abrupt and gradual levee breach analyses on the flat domain were implemented by laboratory experiments and numerical simulations. To avoid the reflective wave from the side wall the experiment was performed in a large domain surrounded by waterway. A numerical model was developed for solving the two-dimensional gradual levee breach flow. The results of the numerical simulation developed in this study showed good agreement with those of the experimental data. However, even if the numerical schemes effectively replicated the trends of the observed water depth for the first shock, there were little differences for the second shock. In addition, even though the model considered the Smagorinsky horizontal eddy viscosity, the location and height of the hydraulic jump in the numerical simulation were not fairly well agree with experimental measurements. This shows the shallow water equation solver has a limitation which does not exactly reproduce the energy dissipation from the hydraulic jump. Further study might be required, considering the energy dissipation due to the hydraulic jump or transition flow from reflective wave.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.5
• /
• pp.557-565
• /
• 2016

The risk of collapse in hydraulic structures has become more elevated, due to the increased probability and scale of flooding caused by global warming and the resulting abnormal climatic conditions. When a levee, a typical hydraulic structure, breaks, an enormous breach flow pours into the floodplain and much flood damage then occurs. It is important to accurately calculate the breach discharge in order to predict this damage. In this study, the variation of the breach discharge with the asymmetry in the cross-section of the levee breach was analyzed. Through hydraulic experiments, the cross-section of the breach was analyzed during the collapse using the BASD (Bilateral ASymmetry Degree), which was developed to measure the degree of asymmetry. The relationship of the breach discharge was identified using the BASD. Additionally, the variation of the breach flow measured by the BASD was investigated through a 3-D numerical analysis under the same flow conditions as those in the experiment. It was found that the assumption of a rectangular breach cross-section, which is generally used for the estimation of the inundation area, can cause the breach discharge to be overestimated. According to the BASD, the breach flow is decreased by the interference effect in the breach section of the levee. If the breach flow is calculated while considering the BASD in the numerical analysis of the flooding, it is expected that the predicted inundation area can be estimated accurately.

• Journal of Korea Water Resources Association
• /
• v.55 no.6
• /
• pp.471-480
• /
• 2022

In this study, a integrated platform applied with various analysis and evaluation models and data collection modules was developed for urban river management. Modules applied to the integrated platform are data collection and provision module, flood analysis module, river evaluation module, and levee breach simulation module, which were selected and applied for efficient urban river management. The integrated platform collects data for application to analysis and evaluation modules from various institutions. The collected data is refined through pre-processing and stored. The stored data is used as input data for each module and is also provided as an Open API through the platform. The flood analysis module is provided to analyze and prepare for floods occurring in cities and rivers. The river evaluation module is used for river planning and management by evaluating rivers in various ways. Finally, the levee breach simulation module can be used to establish countermeasures by deriving a possible damage area due to levee breach through analysis of a virtual breach situation.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.1
• /
• pp.537-544
• /
• 2017

An experimental study was carried out to investigate the characteristics of the propagation distance of a flood wave considering the levee failure speed in a flat inundation area. The Ritter solution for one dimensional flow was considered to formulate the experimental results and a representative form with coefficients of k and m, which consider the three dimensional flow characteristics, was applied. The experiments showed that the propagation velocity of the wave front in the inundation area was influenced by the levee breach speed as well as the initial water level, which is a significant variable representing the flood wave behavior. In addition, coefficients k and m are not constants, but variables that vary with levee breach speed. An empirical formula was also suggested using the experimental results in the form of the relationships between k and m. In this study, a large-scale experiment for flood inundation was carried out to examine the behavior of flooding in the inundated area and the relationships between the levee breach speed and wave-front propagation velocity were suggested based on the experimental results. These research results are expected to be used as the baseline data to draw a flow inundation map, establish an emergency action plan, and verify the two-dimensional numerical model.

• Journal of Convergence for Information Technology
• /
• v.9 no.11
• /
• pp.125-133
• /
• 2019

In this paper, probabilistic flood risk maps were produced for levee break caused by possible flood scenarios. The results of the previous studies were employed for flood stages corresponding to hydrological extreme event quantified uncertainties and then predicted the location of a levee breach. The breach width was estimated by combining empirical equation considered constant width and numerical modeling considered uncertainties on compound geotechnical component. Accordingly, probabilistic breach outflow was computed and probabilistic inundation map was produced by 100 runs of 2D inundation simulation based on reliability analysis. The final probabilistic flood risk map was produced by combining probabilistic inundation map based on flood hazard mapping methodology. The outcomes of the study would be effective in establishing specified emergency actin plan (EAP) and expect to suggest more economical and stable design index.