• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.12
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• pp.17-25
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• 2017

Owing to recent climate change, the scale of rainfall tends to increase gradually and the risk of flooding has increased. Therefore, the importance of improving the levee management and disaster response is increasing. Levee management in Korea is carried out at the level of damage recovery after the occurrence of damage. Therefore, it is necessary to develop a technology for predicting and managing the levee safety with proactive river management. In this study, a method to estimate the safety against erosion and overflow was suggested. A map of levee safety that can be used as basic data is presented by displaying the levee safety on the map. The levee erosion safety was calculated as the ratio of the internal and external force for each shore type. The levee overflow safety was calculated as the ratio of the maximum conveyance and design flood. The maximum conveyance was a discharge when the level of the river was equal to the level of the levee crown. The levee safety was classified into 5 grades: very safe, safe, normal, dangerous, and very dangerous. As a research area from downstream of Nam River Dam to Nakdong River Junction, the levee safety against erosion and overflow was estimated for all levees and all cross-sections of the river. The levee safety was displayed on a map using GIS. Through the levee safety map as a result of this study, the levee safety can be observed intuitively. Using the levee safety map, a maintenance plan for a river can be easy to build. This levee safety map can be used to help determine the priority of investment for efficient budget used.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.9
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• pp.20-29
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• 2018

Owing to the changing climate and recent flood events, flood damage caused by river levee collapse and overflow is on the rise in Korea, making it necessary to enhance river levee maintenance technologies to deal with various flood damage scenarios. This paper proposes the evaluation system of a river-levee safety map to improve maintenance efficiency and disaster responsiveness. A river-levee safety map, indicating sliding, piping, visual inspection, scouring, and safety index of a levee fill material on a GIS map will enable the dangerous zone to be identified visually and the development of proactive measures to deal with it. This will maximize the river-levee maintenance efficiency, which is a break from traditional practice in that restoration measures are taken only after the damage has occurred. This study includes scouring and levee fill material in addition to previously-proposed sliding, piping and visual inspections. The research activities conducted in the study include 1) categorization of scouring and levee fill material based on document and data examination, 2) evaluation of sliding and piping at 5 locations on the left levee in the Nam river according to the duration time of the flood water level, and 3) evaluation of the characteristics of scouring and levee fill material at 9 locations on the left/right levee in the Nam River. The river levee safety map proposed in this study would be more useful and practical but further study on the manual for river management organization, repair and reinforcement methods, and budget is required.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.12
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• pp.768-777
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• 2017

The efforts to improve river levee maintenance technologies have accelerated globally in a bid to deal with the flood damage resulting from the changes to the climate and flood events. This paper, in line with such tendency, proposes an evaluation system of a river levee safety map to maintain the river levee in an efficient manner. The concept of a river levee safety map is aimed at maximizing the maintenance efficiency for a manager to indicate the safety index, including the current river levee sliding, piping, and visual inspection on a GIS map. To develop such an evaluation system, a safety index covering the sliding, piping, and visual inspection are designated through the data and document examination and the rational guideline to classify each index into three grades, A, B, and C, is proposed. Based on the guideline proposed, the sliding and piping characteristics in terms of safety depending on the change to the flood water level duration time at the test section (Nam river) were evaluated by numerical analysis. As a result, both the protected landside and riverside satisfied the requirements for Grade A in terms of sliding, and when it comes to piping, the grade declined to C because the flood water level duration time increased at R2. As a planning study to propose a river levee safety map evaluation system, a further advanced study, standardization of the river levee data, and improvement of the existing system and laws are required.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.6B
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• pp.533-540
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• 2010

Recently management of vegetation distributed in the watercourse is very important not only for safety but also for river restoration. In general, vegetations in the watercourse increase hydraulic resistance and accordingly decrease conveyance capacity which may yield levee overflow. This paper simulates water level rise using 1D and 2D hydro dynamic model to check the possibility of overflow in downstream of the Soyang Reservoir by assigning different roughness coefficient corresponding to different types of vegetation. In this study, 3 different vegetation types of tree, shrub, and main channel were considered and corresponding Manning's roughness coefficient n was assigned based on the vegetation map generated from the site investigation. As results, the water level raised about 0.1 to 0.7 m comparing with the case without considering vegetation and a proper measurements is necessary where overflow occurs due to low level levee.