• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.28 no.3B
• /
• pp.271-281
• /
• 2008

To determine the flood protection elevation (FPE) in urban built-up areas, this study examines four possible methods: using the highest flood elevation in the past, extending base flood elevations of nearby watercourse to inland, and two simulation methods of inland flood under the same rainfall used in the watercourse planning nearby. According to the case study of the Jang-An Drainage Area, Seoul, the highest flood elevation in the past and simulation results of inland flood under the same rainfall in the watercourse planning nearby tend to get similar results, while extending base flood elevations of nearby watercourse to inland shows much higher elevations than other results. Meanwhile, cost-benefit analysis, when regulating residential/commercial uses below the FPE by each of four methods, suggest that planners need to consider carefully the economic feasibility of FPE used to choose appropriate methods.

• Journal of the Korean Society of Hazard Mitigation
• /
• v.5 no.4 s.19
• /
• pp.1-8
• /
• 2005

In this study, a numerical model combined by a river model and an inland model developed to simulated a flood event. The river model describing an inundation in a river solves the two-dimensional Saint Venant equations with a finite difference method. The inland model based on the ILLUDAS describes the conveyance capacity of a storm sewer system. The combined model is applied to a real situation. The model simulates reasonably the real flood event occurred in a river and inland simultaneously.

• Proceedings of the Korean Institute of Landscape Architecture Conference
• /
• 2021.10a
• /
• pp.141-143
• /
• 2021

• Proceedings of the Korea Water Resources Association Conference
• /
• 2005.05b
• /
• pp.1047-1052
• /
• 2005

The purpose of this study is developing a coupled model for the flood analysis. Firstly, the model(river model) describing the inundation in a river solves the two-dimensional Saint Venant equations with a finite difference method and it is possible moving boundary treatment. The other model(inland model) in developed based on the ILLUDAS model to describe the conveyance capacity of a stormwater sewer system. Finally, a coupled model is applied to a real situation. The newly developed coupled model simulates reasonably the flood event occurred in a river and a inland simultaneously

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.15 no.4
• /
• pp.2460-2468
• /
• 2014

A local rain that is concentrated in specific area in a short time frequently occurs due to recent abnormal weather. To prevent potential flood disasters, therefore, it is necessary to be established to the flood control system. Checking the river design standard, however, hydrologic design frequency of water gate is only marked as over 20 years, so this fact shows that the standard is unclear. The inland inundation modeling considering the stage in a river and quantitative assessment are required to reduce flood damage. The simulation for internal inundation is very complex and is time-consuming due to considering hydraulic hydrology characteristics at the same time. Using the already established river master plan, consequently, this study proposed the simple and convenient method for assessment of the internal inundation simulation. Using the proposed method in the upper and middle regions of a river, influences for design frequency or water gate location were assessed by applying the nine probability precipitation with design frequency and by targeting the water gates which are installed in five inlands.

• Ecology and Resilient Infrastructure
• /
• v.10 no.2
• /
• pp.40-49
• /
• 2023

To reduce the damage of extreme flooding caused by climate change and to create flood mitigation sections in a nature-friendly riparian area, it is necessary to restore the floodplain area by referring to the past floodplain section of the current inland waterfront area before the levee was built. This study proposed a method of selecting a location for floodplain restoration using old maps of the Geum River study section and analyzed the effect of flood level reduction through unsteady flow numerical simulations using the floodplain as a flood mitigation space. As a result of analyzing changes in the river areas using old maps, the river section was estimated to gradually reduce by 27.8% (1,059,380 m²) in 2020 compared to 1919, and it was found to have an effective storage capacity of 2,200,868 m³ when restored to offline storage. The flood level and discharge control effects analyzed based on HEC-RAS unsteady flow simulation were 16 cm and 219.01 m³/s, respectively, in the downstream cross-section. In the numerical simulation in this paper, the flood mitigation space was applied as an offline reservoir. The effect of reducing the flood level may differ if levee retreat/relocation is applied.

• Journal of the Korean Society of Safety
• /
• v.35 no.2
• /
• pp.100-110
• /
• 2020

Recently, the frequency of typhoon and torrential rain due to climate change is increasing. In addition, the upsurge in the complexity of urban sewer network and impervious surfaces area aggravates the inland flooding damage. In response to these worsening situations, the central and local governments are conducting R&D tasks related to predict and mitigate the flood risk. Researches on the analysis of inundation in urban areas have been implemented through various ways, and the common features were to evaluate the accuracy and justification of the model by comparing the model results with the actual inundation data. However, the evaluation procesure using available urban flooding data are not consistent, and if there are no quantitative urban inundation data, verification has to be performed by using press releases, public complaints, or photos of inundation occurring through 'CCTV'. Because theses materials are not quantitative, there is a problem of low reliability. Therefore, this study intends to develop a comparative analysis procedure on the quantitative degree and applicability of the verifiable inundation data, and a systematic framework for the performance assessment of urban flood analysis model was proposed. This would contribute to the standardization of the evaluation and verification procedure for urban flooding modelling.

• Journal of Ocean Engineering and Technology
• /
• v.36 no.6
• /
• pp.364-379
• /
• 2022

Coastal communities have been vulnerable to extreme coastal flooding induced by hurricanes and tsunamis. Many studies solely focused on the overland flow hydrodynamic and loading mechanisms on individual inland structures or buildings. Only a few studies have investigated the effects of flooding mitigation measures to protect the coastal communities represented through a complex series of building arrays. This study numerically examined the performance of flood-mitigation measures from tsunami-like wave-induced overland flows. A computational fluid dynamic model was utilized to investigate the performance of mitigation structures such as submerged breakwaters and seawalls in reducing resultant forces on a series of building arrays. This study considered the effects of incident wave heights and four geometrically structural factors: the freeboard, crest width of submerged breakwaters, and the height and location of seawalls. The results showed that prevention structures reduced inundation flow depths, velocities, and maximum forces in the inland environment. The results also indicated that increasing the seawall height or reducing the freeboard of a submerged breakwater significantly reduces the maximum horizontal forces, especially in the first row of buildings. However, installing a low-lying seawall closer to the building rows amplifies the maximum forces compared to the original seawall at the shoreline.

• Journal of Korea Water Resources Association
• /
• v.48 no.12
• /
• pp.1065-1075
• /
• 2015

In the estuary where the structure such as river-mouth weir has been installed, the flow is developed very complicatedly due to river water from upstream, tide of the sea and floodgate operation. Especially, if basin outlets more than one exists in one estuary, the boundary conditions will be significantly more complex form. Saemangeum(SMG) project area in Korea is the most typical example. There are Mankyung river and Dongjin river in upstream. The water of them inflows into SMG project area. In the downstream, river flow was drained from inland to sea over the SMG sea dike through the sluice. The connecting channel was located between Mankyung and Dongjin basins. It functions not only as transportation by ship in ordinary period but also as flood sharing by sending flood flow to each other in flood period. Therefore, in order to secure the safety against flood, it is very important to understand the flood sharing capacity for connecting channel. In this study, the flood control effect was analyzed using numerical simulation. Delft3D was used to numerical simulation and simulated period was set up with neap tide, in which the maximum flood stage occurred due to poor drainage. Actually, three connecting channels were designed in land use plan of the SMG Master Plan, but they were simplified to a single channel for conciseness of analysis in this study. According to the results of numerical analysis, the water level difference between two basins was increased and the maximum flood stage at dike sluice was also upraised depending on decrease of conveyance. And the velocity induced by same water level difference was decreased when the conveyance became smaller. In certain conveyance above, there was almost no flood control effect. Therefore, if the results of this study are considered for design of connecting channel, it will be expected to draw the optimal conveyance for minimizing dredging construction cost while maximizing the flood control effect.

• Journal of Korean Port Research
• /
• v.13 no.2
• /
• pp.419-426
• /
• 1999

It is essential for port planning, coastal zone management and environmental impact study to analyze the variation of current and water quality due to the development of water area and discharged water from estuary barrage and basin etc. Mokpo sea area downstreams from a long river and two large basins, the Yongsan river and Yongam-Kumho basins discharging much of water through water gates for the purpose of flood control and prohibition of salt intrusion to the inland fresh water area. In this study, the numerical calculations were carried out for the analysis of diffusion characteristics due to discharging operation, adapting the results of tidal current simulation ADI methord is applied to the governing equation for the movement of sea water and diffusion and 6-point method to the advection terms of diffusion equation. As the results of this study, it is known that the discharging operation causes increasing and/or decreasing of current velocity and enlarging and/or depressing of pollutant diffusion limits depending on the distance from the discharging gates and the mode of discharging operation. To utilize these result, the linked gate operation and the method increasing exchange of sea water must be considered.