• Title/Summary/Keyword: Design Flood Level

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Analysis of Flood Control Capacity of Agricultural Reservoir Based on SSP Climate Change Scenario (SSP 기후변화 시나리오에 따른 농업용 저수지 홍수조절능력 분석)

  • Kim, Jihye;Kwak, Jihye;Hwang, Soonho;Jun, Sang Min;Lee, Sunghack;Lee, Jae Nam;Kang, Moon Seong
    • Journal of The Korean Society of Agricultural Engineers
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    • v.63 no.5
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    • pp.49-62
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    • 2021
  • The objective of this study was to evaluate the flood control capacity of the agricultural reservoir based on state-of-the-art climate change scenario - SSP (Shared Socioeconomic Pathways). 18 agricultural reservoirs were selected as the study sites, and future rainfall data based on SSP scenario provided by CMIP6 (Coupled Model Intercomparison Project 6) was applied to analyze the impact of climate change. The frequency analysis module, the rainfall-runoff module, the reservoir operation module, and their linkage system were built and applied to simulate probable rainfall, maximum inflow, maximum outflow, and maximum water level of the reservoirs. And the maximum values were compared with the design values, such as design flood of reservoirs, design flood of direct downstream, and top of dam elevation, respectively. According to whether or not the maximum values exceed each design value, cases were divided into eight categories; I-O-H, I-O, I-H, I, O-H, O, H, X. Probable rainfall (200-yr frequency, 12-h duration) for observed data (1973~2020) was a maximum of 445.2 mm and increased to 619.1~1,359.7 mm in the future (2011~2100). For the present, 61.1% of the reservoirs corresponded to I-O, which means the reservoirs have sufficient capacity to discharge large inflow; however, there is a risk of overflowing downstream due to excessive outflow. For the future, six reservoirs (Idong, Baekgok, Yedang, Tapjung, Naju, Jangsung) were changed from I-O to I-O-H, which means inflow increases beyond the discharge capacity due to climate change, and there is a risk of collapse due to dam overflow.

A Study on Flood Risk Analysis for A Small Stream in Urban Residential Area (도시 주거지역 내 소하천의 홍수 안정성에 관한 연구)

  • Kwak, Jae-Won;Ahn, Kyoung-Soo;Kyoung, Min-Soo;Kim, Hung-Soo
    • 한국방재학회:학술대회논문집
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    • 2008.02a
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    • pp.195-198
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    • 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.

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Flood risk estimation with scenario-based, coupled river-overland hydrodynamic modeling (시나리오 기반 하천-제내지 연계 통합수리해석에 의한 홍수위험도 산정)

  • Lee, Jae Young;Nam, Myeong Jun;Kwon, Hyun Han;Kim, Ki Young
    • Journal of Korea Water Resources Association
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    • v.49 no.9
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    • pp.773-787
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    • 2016
  • A coupled river-overland hydrodynamic model was applied to estimate flood risk by a scenario-based approach. The study area is Seongseo Industrial Complex in Daegu which is located near Nakdong river and Geumho river. Inundation depth and velocity at each time were calculated by applying a coupled 1D/2D hydrodynamic model to the target area of interest. The 2D inundation analysis for river and overland domain was performed with the scenario-based approach that there are levee overflow against 100/200 year high quantile (97.5%) design flood and levee break against 100/200 year normal quantile (50%) design flood. The level of flood risk was displayed for resident/industrial area using information about maximum depth and velocity of each node computed from the 2D inundation map. The research outcome would be very useful in establishing specified emergency action plans (EAP) in case of levee break and overflowing resulting from a flood.

Analysis of Flood Control Effects of Heightening of Agricultural Reservoir Dam (농업용 저수지 증고에 따른 홍수조절효과 분석)

  • Lee, Gwan Jae;Park, Ki Wook;Jung, Young Hun;Jung, In Kyun;Jung, Kwang Wook;Jeon, Ji Hong;Lee, Ji Min;Lim, Kyoung Jae
    • Journal of The Korean Society of Agricultural Engineers
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    • v.55 no.4
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    • pp.83-93
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    • 2013
  • Annual average precipitation of Korea is 1,277 mm and around 2/3 of annual precipitation and 74 % of available water resources occurred during monsoon period. In recent years, many agricultural reservoirs have been heightened to increase flood control capacity, reduce flooding damage at downstream areas, and provide sustainable environmental flow during drought period. Thus in this study, the flood control effects of heightening of reservoir banks were simulated with HEC-ResSim and HEC-RAS models. These modes were applied to Bonghak reservoir and it was found that flood control effects were 3~4.5 % with 7 -m heightening. Also, with proper operation (1 m lower of full water level) of reservoir right before the monsoon period, flooding at downstream could be prevented even with design storm of 80 -year recurrence interval. As shown in this study, heightening of agricultural reservoir provides positive effects in flood control and flood damage reduction.

Application of Hydrological Monitoring System for Urban Flood Disaster Prevention (도시홍수방재를 위한 수문모니터링시스템의 적용)

  • Seo, Kyu-Woo;Na, Hyun-Woo;Kim, Nam-Gil
    • Proceedings of the Korea Water Resources Association Conference
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    • 2005.05b
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    • pp.1209-1213
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    • 2005
  • It reflects well feature of slope that is characteristic of city river basin of Pusan local. Process various hydrological datas and basin details datas which is collected through basin basis data. weather satellite equipment(EMS-DEU) and automatic water level equipment(AWS-DEU) and use as basin input data of ILLUDAS model, SWMM model and HEC-HMS model In order to examine outflow feature of experiment basin and then use in reservoir design of experiment basin through calibration and verification about HEC-HMS model. Inserted design rainfall for 30 years that is design criteria of creek into HEC-HMS model and then calculated design floods according to change aspect of the impermeable rate. Capacity of reservoir was determined on the outflow mass curve. Designed imagination reservoir(volume $54,000m^3$) at last outlet upper stream of experiment basin, after designing reservoir. It could be confirmed that the peak flow was reduced resulting from examining outflow aspect. Designing reservoir must decrease outflow of urban areas.

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Optimal Reservoir Operation Using Goal Programming for Flood Season (Goal Programming을 이용한 홍수기 저수지 최적 운영)

  • Kim, Hye-Jin;Ahn, Jae-Hwang;Choi, Chang-Won;Yi, Jae-Eung
    • Journal of the Korean Society of Hazard Mitigation
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    • v.11 no.2
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    • pp.147-156
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    • 2011
  • The purpose of multipurpose reservoir operation in flood season is to reduce the peak flood at a control point by utilizing flood control storage or to minimize flood damage by controlling release and release time. Therefore, the most important thing in reservoir operation for flood season is to determine the optimal release and release time. In this study, goal programming is used for the optimal reservoir operation in flood season. The goal programming minimizes a sum of deviation from the target value using linear programming or nonlinear programming to obtain the optimal alternative for the problem with more than two objectives. To analyze the applicability of goal programming, the historical storm data are utilized. The goal programming is applied to the reservoir system operation as well as single reservoir operation. Chungju reservoir is selected for single reservoir operation and Andong and Imha reservoirs are selected for reservoir system operation. The result of goal programming is compared with that of HEC-5. As a result, it was found that goal programming could maintain the reservoir level within flood control level at the end of a flood season and also maintain flood discharge within a design flood at a control point for each time step. The goal programming operation is different from the real operation in the sense that all inflows are assumed to be given in advance. However, flood at a control point can be reduced by calculating the optimal release and optimal release time using suitable constraints and flood forecasting system.

Derivation of Flood Hazard Curves for SOC Facilities under Local Intensive Precipitation (LIP(극한강우) 조건하에서 중요 SOC 시설물에 대한 재해도 곡선 작성)

  • Kim, Beom Jin;Han, Kun Yeun*
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.39 no.1
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    • pp.183-194
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    • 2019
  • In recent years, the risk of external flooding of major national facilities has increased significantly since 2000 due to the increase in local heavy rainfall events. For important domestic national facilities, it is necessary to analyze the risk of external flooding as flooding in major sites due to heavy rain can cause functional paralysis in major facilities and ultimately lead to massive trouble events. In order to manage the safety of main facilities and its related facilities at a high level, it is necessary to analyze the degree of disaster such as flood depth, flood flow rate, flood time and flood intensity when extreme floods (LIP) are introduced. In addition, the degree of vulnerability of these related facilities should be assessed and risk assessments should be reassessed through linkage analysis that combines the degree of disaster and vulnerability. By calculating a new flood hazard curve for the flood depth and flood intensity in major national facilities under the heavy rainfall conditions through this study, it is expected to be a basis for the waterproof design of important SOC facilities, flood prevention function design, advancement of flood prevention measures and procedures and evaluation of flood mitigation functions.

Failure Probability Analysis of Concrete Cofferdam Considering the Overflow in Flood Season (홍수시 월류를 고려한 콘크리트 가물막이댐의 파괴확률 산정)

  • Hong, Won Pyo;Song, Chang Geun
    • Journal of the Korean Society of Safety
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    • v.35 no.5
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    • pp.30-38
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    • 2020
  • In order to construct a dam, the diversion facility such as cofferdam and a diversion tunnel should be installed in advance. And size of a cofferdam depends on type of a main dam. According to the Korea Dam Design Standard, if the main dam is a concrete dam, design flood of the cofferdam is 1~2 years flood frequency. This means that overflow of the cofferdam occurs one time for 1 or 2 years, therefore, stability of the cofferdam should be secured against any overflow problem. In this study, failure probability analysis for the concrete cofferdam is performed considering the overflow. First of all, limit state function of the concrete cofferdam is defined for overturning, sliding and base pressure, and upstream water levels are set as El. 501 m, El. 503 m, El. 505 m, El. 507 m. Also, after literature investigation research, probabilistic characteristics of various random variables are determined, the failure probability of the concrete cofferdam is calculated using the Monte Carlo Simulation. As a result of the analysis, when the upstream water level rises, it means overflow, the failure probability increases rapidly. In particular, the failure probability is largest in case of flood loading condition. It is considered that the high upstream water level causes increase of the upstream water pressure and the uplift pressure on the foundation. In addition, among the overturning, the sliding and the base pressure, the overturing is the major cause for the cofferdam failure considering the overflow.

Analysis of Flood Level Mitigation due to the Naju Retention-Basin by Numerical Model Application (수치모형 적용을 통한 나주 강변저류지 홍수위 저감효과 분석)

  • Rhee, Dong Sop;Kim, Hyung-Jun;Cho, Gilje
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.15 no.9
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    • pp.5801-5812
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    • 2014
  • The retention basin is a hydraulic structure for flood mitigation by storing river flow over a design flood. In this study, numerical models were adopted to simulate the flood mitigation effects by a retention basin. The large flood condition was applied as a boundary condition to consider an abnormal flood caused by climate change. Furthermore, the two-dimensional numerical model was adopted to regenerate the complex flow pattern due to the topography and lateral flow near the retention basin. The numerical results of the one- and two-dimensional model were analyzed and compared. The results showed that the two-dimensional model is more applicable to assessing flood mitigation by the retention basin with a complex topography and lateral flow patterns.

Failure Probability Assessment for Risk Analysis of Concrete Gravity Dam under Flood (홍수 시 콘크리트 중력식댐의 위험도 분석을 위한 파괴확률 산정)

  • Cho, Soojin;Shin, Sung Woo;Sim, Sung-Han;Lim, Jeong-Yeul
    • Journal of the Korean Society of Safety
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    • v.31 no.6
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    • pp.58-66
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    • 2016
  • This study aims to estimate the failure probability of concrete gravity dams for their risk analysis under flood situation. To the end, failure modes of concrete gravity dams and their limit state functions are proposed based on numerous review of domestic and international literatures on the dam failure cases and design standards. Three failure modes are proposed: overturning, sliding, and overstress. Based on the failure modes the limit state functions, the failure probability is assessed for a weir section and a non-weir section of a dam in Korea. As water level is rising from operational condition to extreme flood condition, the failure probability is found to be raised up to the warning condition, especially for overturning mode at the non-weir section. The result can be used to reduce the risk of the dam by random environmental variables under possible flood situation.