• KCID journal
• /
• v.17 no.2
• /
• pp.28-34
• /
• 2010

This study re-exams hydrologic stability on spillway outlet capacity of agricultural reservoirs using hydrologic data with current rainfall condition instead of project hydrologic data applied at design on Backgok reservoir located in Chungbuk province. It is concluded that Backgok reservoir is not hydrologically stable and therefore structural measures including the extension of spillway and non structural measures should be taken. Continuous basic plan for river maintenance including additional bank reinforcement to bottom river shall be carried out. Due to high peak flood with more than 290% compared to 200 year frequency probability flood which was design standard of the past in view of the results of calculating PMF according to revised design standard for reservoirs, there could a problem for securing rationality in case of applying PMF with design flood. Therefore, hydrological stability, construction, and maintenance cost shall be synthetically studied and reasonal application shall be made if the decision is made on applying PMF with design flood.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.31 no.5
• /
• pp.86-95
• /
• 2003

It had been strictly prohibited to plant in waterway according to Korea laws and regulations. It was then made possible to plant by the modification law and regulation of 10/30/1997. In 2000, the Seoul metropolis government planted in the Yeoyido flood plain park in Han river by way of showing the model case. This planting design is for the Yeoyido flood plain park along the Han river, in Seoul. The design requirements were to create a pleasant rest area, to improve the surrounding landscape, and to create diverse ecological habitats by planting within the stability of flood flow. This design emphasizes the following design requirements that has positive effect on stabilizing flood flow. First, planting suitable in a area was determined by the speed of a current of less than 0.7m/sec under various numerical value simulations. Second, plants were selected in existing trees of the present and the past Han river, as well as the questionnaire results from landscape professional engineers and professors. Shade plants were planted in the large visiting areas so as to offer pleasant shade in the summer, the ecological planting pattern was applied in the area with low speed of flood flow, so as to aid the restoration of the natural ecological environment. It was found that the foresaid planting design verified the stability of flood flow and wind by overturn limit moment calculation. It is expected that this plan would serve environmentally friendly planting plans in flood plain park.

• Journal of the Korean Geotechnical Society
• /
• v.39 no.10
• /
• pp.27-39
• /
• 2023

To effectively manage flood risk, it is crucial to assess the stability of flood defense structures like levees under extreme flood conditions. This study focuses on the time-dependent probabilistic assessment of embankment slope stability when subjected to rapid water level drops. We integrate seepage analysis results from finite element analysis with slope stability analysis and employ Monte Carlo simulations to investigate the time-dependent behavior of the slope during rapid drawdown. The resulting probability of failure is used to develop fragility curves for the levee slope. Notably, the probability of slope failure remains low up to a specific water level, sharply increasing beyond that threshold. Furthermore, the fragility curves are strongly influenced by the rate of drawdown, which is determined through hydraulic analysis based on flood scenarios. Climate change has a significant impact on the stability of the water-side slope of the embankment due to water level fluctuations.

• Journal of the Korean Geotechnical Society
• /
• v.30 no.4
• /
• pp.81-92
• /
• 2014

The integrity evaluation of river levee includes slope stability evaluation of riverside land and protected low-land, and safety of piping with respect to critical gradient and critical velocity based on related regulations, such as Design Criteria Rivers Commentary (2009), Structural Design Criteria Based Commentary (2009). The design hydro-graph is the most important design input factor for the integrity evaluation; it can be inaccurate due to the absence of its decision methods suggested by the national level. The authors in this paper evaluated numerical analytic levee integrity for piping and slope stability by changing each design hydro-graph, including rising ordinary water level, lasting flood water level, falling water level, and flood frequency for Mun-san-jae on Nak-dong River. Finally, the authors suggested that the levee integrity of piping and slope stability are very sensitive to the changes of increasing time of ordinary water level by 57 hours and lasting time of the flood water level by 53 hours, respectively, for Mun-san-jae.

• Proceedings of the Korean Society of Agricultural Engineers Conference
• /
• 2005.10a
• /
• pp.324-329
• /
• 2005

This study considers that hydrologic stability evaluation of agricultural reservoirs designed by past standards and approximate increase methods of flood control when PMF(Probable maximum flood) flows in.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2006.10a
• /
• pp.191-201
• /
• 2006

The flood control ability improvement project on existing dams is the project for prevention of disasters from excessive flood due to climate changes and thus protects lives and property damages by increasing safety of dams. The collapse of dam brings unimaginable disasters, so the project needs to be swiftly conducted by Government's funding. This paper introduces tile examples of the flood control ability improvement projects of multi-purpose and water supply dams, which is conducted in the way of structural measures among 26 dams operated by Kwater.

• The Journal of the Korea Contents Association
• /
• v.10 no.11
• /
• pp.452-460
• /
• 2010

This study carried out stability evaluation for design flood stage of vegetation models with river sites using 1D HEC-RAS and 2D RMA-2 numerical models. The vegetation models established in this study were divided into which channel reaches consist of urban, rural and mountain rivers with the social and cultural significance of the sites. Examination results from the numerical models showed a similar aspect with the design flood stage of these rivers before vegetation modeling. Also, no embankment overflow was shown from the urban river with additional vegetation density of 25%, although there were approximately 0.20m rising in the flood stage. In case of ural and mountain rivers, vegetation models showed scarce rising in flood stage.

• Journal of the Korean Geosynthetics Society
• /
• v.14 no.4
• /
• pp.1-9
• /
• 2015

According to national regulations and its commentary, such as Rivers Design Criteria & Commentary (KWRA, 2009), Foundation Structure Guideline and its Commentary(MLTM, 2014 and KGS, 2009), the integrity evaluation of river levee includes slope stability evaluation of both riverside/protected low-land and piping stability evaluation with respect to foundation and levee body along with water level conditions. In this case the design hydro-graph can be the most important input factor for the integrity evaluation, however it is fact that the national regulations do not provide any proper determination methods regarding hydro-graph. The authors thus executed an integrity evaluation of sluice gate in levee by changing each hydro-graph factor, including rising ordinary water level, lasting flood water level, falling water level, and flood frequency, in order to suggest a determination method of reasonable hydro-graph. As a result, the authors suggested that at least over 57 hours of rising ordinary water level and over 53 hours of lasting flood water level should be considered for the design hydro-graph of sluice gate in levee at Mun-san-jae.

• 한국방재학회:학술대회논문집
• /
• 2008.02a
• /
• pp.195-198
• /
• 2008

In this study we analyzed flood runoff and flood characteristics of an small urban river basin which is in an apartment complex in Yewol-Dong, Buchun-Si, Gyunggi-Do. A little discharge normally flows in the river, however this small river has a relatively high potential of flood damage risk in the flood season due to the high flood level and velocity. Therefore we used the GIS data, cross section data in the river, HEC-RAS model, etc. for investigating safety of a river against flood runoff and also we investigated the stability of hydraulic structures and ability of flood prevention in the river. As the result of investigation, we found that the river had the risk of flood damage occurrence due to the hydraulic structures constructed for various purposes in the river. So we should analyze backwater effect by the structures and consider the risk factors can be occurred by the flood runoff and velocity for more safe design of a small river basin in the residential area such as an apartment complex in the urban area.

• Journal of Korean Society of Disaster and Security
• /
• v.14 no.2
• /
• pp.61-75
• /
• 2021

Recently, as the occurrence frequency of sudden floods due to climate change increased and the aging of the existing spillway, it is necessary to establish a plan to utilize an auxiliary spillway to minimize the flood damage of downstream rivers. Most studies have been conducted on the review of flow characteristics according to the operation of auxiliary spillway through the hydraulic experiments and numerical modeling. However, the studies on examination of flood damage in the downstream rivers and the stability of the revetment according to the operation of the auxiliary spillway were relatively insufficient in the literature. In this study, the stability of the revetment on the downstream river according to the outflow conditions of the existing and auxiliary spillway was examined by using 3D numerical model, FLOW-3D. The velocity, water surface elevation and shear stress results of FLOW-3D were compared with the permissible velocity and shear stress of design criteria. It was assumed the sluice gate was fully opened. As a result of numerical simulations of various auxiliary spillway operations during flood season, the single operation of the auxiliary spillway showed the reduction effect of maximum velocity and the water surface elevation compared with the single operation of the existing spillway. The stability of the revetment on downstream was satisfied under the condition of outflow less than 45% of the design flood discharge. However, the potential overtopping damage was confirmed in the case of exceeding the 45% of the design flood discharge. Therefore, the simultaneous operation with the existing spillway was important to ensure the stability on design flood discharge condition. As a result of examining the allocation ratio and the total allowable outflow, the reduction effect of maximum velocity was confirmed on the condition, where the amount of outflow on auxiliary spillway was more than that on existing spillway. It is because the flow of downstream rivers was concentrated in the center due to the outflow of existing spillway. The permissible velocity and shear stress were satisfied under the condition of less than 77% of the design flood discharge with simultaneous operation. It was found that the flood damage of downstream rivers can be minimized by setting the amount allocated to the auxiliary spillway to be larger than the amount allocated to the existing spillway for the total outflow with simultaneous operation condition. However, this study only reviewed the flow characteristics around the revetment according to the outflow of spillway under the full opening of the sluice gate condition. Therefore, the various sluice opening conditions and outflow scenarios will be asked to derive more efficient utilization of the auxiliary spillway in th future.