scholarly journals Sensitivity analysis for dam breach parameters using different approaches for earth-fill dam

2021 ◽  
Vol 14 (4) ◽  
pp. 90-97
Author(s):  
Israa Dheyaa Abdulrazzaq ◽  
Qassem H. Jalut ◽  
Jasim M. Abbas
Keyword(s):  
Sensitivity Analysis ◽  
Formation Time ◽  
Dam Breach ◽  
Side Slope ◽  
Operating Level ◽  
Dam Site ◽  
Breach Parameters ◽  
Overtopping Failure ◽  
Dam Breaking ◽  
Breach Width

The prediction of dams breach geometry crucial in studies of dam breaking. The hydrographs characteristics of flood that resulting from breaking of dam is mainly depend on the geometry of breach and the time formation of breach. Five approaches (Froehlich, Macdonald and Langridge-Monopolis, Von thun & Gillete, USBR and Singh % Snorrason) was used in order to predict dam breach parameters (breach width, breach side slope, breach formation time). The Sensitivity analysis was performed in order to assess the effect of each parameter on the resulting hydrograph of the flood. HEC-RAS model was used to calculate the effect of each parameter on the hydrograph of the flood that resulted. The width of breach (Bavg), side slope (z) and formation time of breach (tf) increased by 25%, 50%, 75% and 100% and decreased by 25%, 50% and 75%, respectively. Flood hydrograph was estimated at the dam site for each case. Sensitivity analysis was performed in order to check the effect of each parameter of breach and time of breaching. Sensitivity analysis was performed with Froehlich method with the mode of overtopping failure and maximum operating level at 107.5 meter above sea level. Result of sensitivity analysis show that peak discharge and time to reach it is adequately sensitive to breach side slope, highly sensitive to the breach formation time and less sensitive to breach width.

scholarly journals Modeling and Risk Analysis of Dam-Break Flooding in a Semi‐Arid Montane Watershed.

2021 ◽  
Author(s):  
Aissam Gaagai ◽  
Hani Amir Aouissi ◽  
Andrey E. Krauklis ◽  
Juris Burlakovs ◽  
Ali Athamena ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Maximum Flow ◽  
Dam Break ◽  
Formation Time ◽  
Dam Failure ◽  
Wave Flow ◽  
Flood Wave ◽  
Embankment Dam ◽  
Breach Parameters ◽  
The Impact

The risk related to embankment dam breaches needs to be evaluated in order to prepare emergency action plans. The physical and hydrodynamic parameters of the flood wave generated from dam-failure event correspond to various breach parameters such as width, slope and formation time. This study aimed to simulate dam-breach failure scenario of Yabous dam (NE Algeria) and analyze its influence on areas (urban and natural environments) downstream the dam. The simulation was completed using the sensitivity analysis method in order to assess the impact of breach parameters on the dam-break scenario. The propagation of flood wave associated to dam-break was simulated using the one-dimensional HEC-RAS hydraulic model. This study ap-plied a sensitivity analysis of three breach parameters (slope, width, and formation time) in five sites selected downstream the embankment dam. The simulation showed that the maximum flow of the flood wave recorded at the level of the breach was 8768 m3/s, which gradually attenuated along the river course to reach 1579.2m3/s at about 8.5km downstream the dam. This study estab-lished the map of flood-prone areas that illustrated zones threatened with the flooding wave trig-gered by the dam failure due to extreme rainfall events. The sensitivity analysis showed that flood wave flow, height and width revealed positive and similar changes for the increase in adjustments (±25% and ±50%) of breach width and slope in the 5 sites. However, flood wave parameters of breach formation time showed significant trends that changed in the opposite direction compared to breach slope and width.

scholarly journals Factors influencing the sediment delivery ratio of the Three Gorges Reservoir

2018 ◽  
Vol 40 ◽  
pp. 03019
Author(s):  
Dayu Wang ◽  
Chunhong Hu ◽  
Chunming Fang ◽  
Jianzhao Guan ◽  
Lei Zhang
Keyword(s):  
Sensitivity Analysis ◽  
Three Gorges Reservoir ◽  
Delivery Ratio ◽  
Three Gorges ◽  
Sediment Delivery Ratio ◽  
Sediment Delivery ◽  
Shape Coefficient ◽  
The Three Gorges Reservoir ◽  
The Three Gorges ◽  
Dam Site

In recent years, the sediment delivery ratio (SDR) of the Three Gorges reservoir (TGR) has noticeably decreased as a result of the increase in water levels at the dam site and the decrease in inflow of fine particles, thereby resulting in increased reservoir siltation. Therefore, it is vital to research the factors that influence the SDR of the TGR. Factors that could have impact on the SDR were studied using TGR monitoring data. The study indicated that the water level at the dam site and inflow and outflow rates could have contributed to the change in the SDR. A sensitivity analysis of the influencing factors was then carried out using a mathematical model to simulate numerous sediment movement scenarios in the TGR. By changing the input conditions of the model, sufficient results were obtained to enable a sensitivity analysis of each factor. The results showed the flood retention time (FRT)—the ratio of reservoir capacity to average outflow discharge—was the principal factor influencing the SDR. The other factors (inflow sediment concentration, inflow sediment coefficient, inflow sediment gradations, and the shape coefficient of the inflow flood shape coefficient), also had an influence on the SDR. However, under different levels of FRT, their degrees of influence on the SDR were not the same..

scholarly journals Overtopping Failure of a Reinforced Tailings Dam: Laboratory Investigation and Forecasting Model of Dam Failure

Water ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 315 ◽  
Author(s):  
Xiaofei Jing ◽  
Yulong Chen ◽  
David Williams ◽  
Marcelo Serna ◽  
Hengwei Zheng
Keyword(s):  
Loss Rate ◽  
Dam Failure ◽  
Forecasting Model ◽  
Tailings Dam ◽  
Dam Breach ◽  
Loss Of Life ◽  
Physical Model Tests ◽  
Significant Damage ◽  
Overtopping Failure ◽  
Overtopping Erosion

Overtopping failure of reinforced tailings dam may cause significant damage to theenvironment and even loss of life. In order to investigate the feature of overtopping of the reinforcedtailings dam, which has rarely appeared in the literature, the displacement, the phreatic level and theinternal stress of dam during overtopping were measured by a series of physical model tests. Thisstudy conclusively showed that, as the number of reinforcement layers increased, the anti-erosioncapacity of tailings dam was notably improved. It could be supported by the change of the dimensionof dam breach, the reduction of stress loss rate, and the rise of phreatic level from the tests. Based onthe erosion principle, a mathematical model was proposed to predict the width of the tailings dambreach, considering the number of reinforcement layers. This research provided a framework for theexploration of the overtopping erosion of reinforced tailings dam, and all presented expressions couldbe applied to predict the development of breach during overtopping.

Sensitivity Analysis of Dam Breach Parameters for Variation Capacity Earthen Dams

2021 ◽  
Vol 18 (3) ◽  
pp. 1-9
Author(s):  
Chau Kim Tran
Keyword(s):  
Sensitivity Analysis ◽  
Development Time ◽  
Failure Process ◽  
Parameter Analysis ◽  
Earth Dam ◽  
Dam Failure ◽  
Fast Method ◽  
Input Variables ◽  
Rising Time ◽  
Breach Width

Sensitivity analysis is an effective tool to determine the robustness of an assessment by examining the extent to which the results are affected by changes in input. In this study, the FAST method was applied to analyse the sensitivity to the earth dam failure process. Four (04) input variables were selected including breach development time, breach width, side slope, and initial breach position. The effects of these parameters on the two (02) outputs i.e., the maximum outflow, and rising time were assessed. The study was applied to 08 reservoirs with different capacities. The sensitivity analysis showed that the development time and initial breach location dominantly affect these outputs. Additionally, development time is the most important factor in rising time. The lateral slope has an insignificant effect on outputs. The effect of breach width can be neglected to rising time, however, its influence on maximum outflow is significant. The results of this study show the role of input variables in the flow hydrograph due to dam failure. Through this research, the workload of the breach parameter analysis process can be substantially reduced.

scholarly journals An evaluation of existent methods for estimation of embankment dam breach parameters

2017 ◽  
Vol 87 (1) ◽  
pp. 545-566 ◽  
Author(s):  
Saad Sh. Sammen ◽  
T. A. Mohamed ◽  
A. H. Ghazali ◽  
L. M. Sidek ◽  
A. El-Shafie
Keyword(s):  
Embankment Dam ◽  
Dam Breach ◽  
Breach Parameters

scholarly journals 2D-HEC-RAS Modeling of Flood Wave Propagation in a Semi-Arid Area Due to Dam Overtopping Failure

2021 ◽  
Vol 7 (9) ◽  
pp. 1501-1514
Author(s):  
Ibtisam R. Karim ◽  
Zahraa F. Hassan ◽  
Hassan Hussein Abdullah ◽  
Imzahim A. Alwan
Keyword(s):  
Wave Propagation ◽  
Flow Velocity ◽  
Water Depth ◽  
Dam Break ◽  
Flood Wave ◽  
Dam Breach ◽  
Inundation Maps ◽  
Overtopping Failure ◽  
Dam Overtopping ◽  
The Impact

Dam overtopping failure and the resulting floods are hazardous events that highly impact the inundated areas and are less predictable. The simulation of the dam breach failure and the flood wave propagation is necessary for assessing flood hazards to provide precautions. In the present study, a two-dimensional HEC-RAS model was used to simulate the flood wave resulting from the hypothetical failure of Al-Udhaim Dam on Al-Udhaim River, Iraq, and the propagation of the resulting dam-break wave along 100 km downstream the dam site for the overtopping scenario. The main objective is to analyze the propagation of the flood wave so that the failure risk on dam downstream areas can be assessed and emergency plans may be provided. The methodology consisted of two sub-models: the first is the dam breach failure model for deriving the breach hydrograph, and the second is the hydrodynamic model for propagating the flood wave downstream of the dam. The breach hydrograph is used as an upstream boundary condition to derive the flood impact in the downstream reach of Al- Udhaim River. The flood inundation maps were visualized in RAS-Mapper in terms of water surface elevation, water depth, flow velocity, and flood arrival time. The maximum recorded values were: 105 m (a.m.s.l.), 18 m, 5.5 m/s, and, respectively. The flow velocity decreased from upstream to downstream of the terrain, which means less risk of erosion in the far reaches downstream of the study area. The inundation maps indicated that the water depth and flow velocity were categorized as Catastrophic limits on the terrain's area. The results offer a way to predict flood extent and showed that the impact of a potential dam break at Al-Udhiam Dam will be serious, therefore, suitable management is needed to overcome this risk. Moreover, the maps produced by this study are useful for developing plans for sustainable flood management. Doi: 10.28991/cej-2021-03091739 Full Text: PDF

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