scholarly journals Computation of Hydraulic Characteristics of Flood Flow Downstream from the Reservoir with Dam Safety Scenarios in North Vietnam

10.29007/7gg6 ◽  
2018 ◽  
Author(s):  
Thu Hien Thi Le ◽  
Viet Hung Ho
Keyword(s):  
Numerical Model ◽  
Water Resource Management ◽  
Dam Break ◽  
Arch Dam ◽  
Dam Safety ◽  
Hydraulic Characteristics ◽  
Maximum Water Level ◽  
Indispensable Tool ◽  
North Vietnam ◽  
Volume Method

Using a reservoir is an effective solution to prevent lowland flooding and mitigate socio-economic damages. However, due to the high density of river network and the presence of reservoirs, dam safety assurance is becoming one of the most important mission in water resource management in Vietnam. Hydraulic characteristics of dam-break wave are necessary information to generate early warning plans for downstream area of reservoir. To aim this purpose, the Finite Volume Method with Godunov-type is considered to solve two-dimensional shallow water equations and develop a numerical model. In this study, the numerical model for dam-break simulation is suggested and verified through a comparison between calculated results and observed data of two reference tests. Very good agreement shows the effectiveness and accuracy of the proposed model. The Nam Chien reservoir in Vietnam has been chosen and the numerical model is applied to simulate flooding wave for the scenario of arch dam collapse. Alternative solutions are produced, such as: water depth, discharge hydrographs, arrival time, time to reach maximum water level; flooding map. The simulated result implies that this model is an indispensable tool for simulating dam-break scenarios.

scholarly journals 2D numerical modelling of dam break- applying for Namchien dam in Vietnam

2019 ◽  
Vol 8 (9) ◽  
pp. 711-716
Keyword(s):  
Dam Break ◽  
Arch Dam ◽  
Roughness Coefficient ◽  
Proposed Model ◽  
Nonlinear Shallow Water Equations ◽  
Time Histories ◽  
Friction Term ◽  
Dam Break Flow ◽  
High Roughness ◽  
Volume Method

The paper is dedicated to study a numerical model simulating dam-break based on two dimensional nonlinear shallow water equations (2D-NSWE). Finite Volume Method-Godunov type is applied to discretize this equation. Roe scheme is utilized to approximate Riemann problem, meanwhile method of flux difference splitting is implemented to construct numerical solvers of SWE. Besides, the semi implicit scheme is also invoked to solve friction term in case of high roughness coefficient. The proposed model is verified through a comparison between computed results and empirical data of two reference tests. A dam break flow over floodable area with different roughness coefficients is also researched. A total collapsed dam scenario of an arch dam-Nam Chien in Vietnam is simulated by the proposed model. Several hydraulic characteristics such as flood extent, arrival time and time histories of water depth at different gauges are estimated with different grid sizes.

scholarly journals Interactions Study of Hydrodynamic-Morphology-Vegetation for Dam-Break Flows

2016 ◽  
Vol 2016 ◽  
pp. 1-12
Author(s):  
Mingliang Zhang ◽  
Yuanyuan Xu ◽  
Jin Li ◽  
Huiting Qiao ◽  
Hongxing Zhang
Keyword(s):  
Numerical Model ◽  
Morphological Changes ◽  
Flow Region ◽  
Dam Break ◽  
Plant Distribution ◽  
Computational Domain ◽  
Dam Break Flow ◽  
Volume Method ◽  
Two Sides ◽  
Morphology Characteristics

This study models a dam-break flow over a bed by using a depth-averaged numerical model based on finite-volume method and computes the dam-break flow and bed morphology characteristics. The generalized shallow water equations considering the sediment transport and bed change on dam-break flow are adopted in the numerical model, and the vegetation effects on the flow and morphological changes are considered. The model is verified against three cases from the laboratory and field data documented in the literature. The numerical results are consistent with the measured results, which show that the model could accurately simulate the evolution of the dam-break flows and the morphology evolution of bed within a computational domain with complex plant distribution. The results show that the riparian vegetation in the waterway narrows the channel and reduces the conveyance capacity of river. The flood flow is diverted away from the vegetation community toward two sides and forms a weak flow region behind the vegetation domain. The resistance of plants markedly reduces the flow velocity, which directly alters the fluvial processes and influences the waterway morphology.

scholarly journals Evaluation of Operational Monsoon Moisture Surveillance and Severe Weather Prediction Utilizing COSMIC-2/FORMOSAT-7 Radio Occultation Observations

2021 ◽  
Vol 13 (15) ◽  
pp. 2979
Author(s):  
Yu-Chun Chen ◽  
Chih-Chien Tsai ◽  
Yi-Chao Wu ◽  
An-Hsiang Wang ◽  
Chieh-Ju Wang ◽  
...  
Keyword(s):  
Numerical Model ◽  
Data Assimilation ◽  
Water Resource Management ◽  
Radio Occultation ◽  
Positive Impact ◽  
Weather Prediction ◽  
Severe Weather ◽  
Model Experiments ◽  
Typhoon Structure ◽  
Numerical Model Experiments

Operational monsoon moisture surveillance and severe weather prediction is essential for timely water resource management and disaster risk reduction. For these purposes, this study suggests a moisture indicator using the COSMIC-2/FORMOSAT-7 radio occultation (RO) observations and evaluates numerical model experiments with RO data assimilation. The RO data quality is validated by a comparison between sampled RO profiles and nearby radiosonde profiles around Taiwan prior to the experiments. The suggested moisture indicator accurately monitors daily moisture variations in the South China Sea and the Bay of Bengal throughout the 2020 monsoon rainy season. For the numerical model experiments, the statistics of 152 moisture and rainfall forecasts for the 2020 Meiyu season in Taiwan show a neutral to slightly positive impact brought by RO data assimilation. A forecast sample with the most significant improvement reveals that both thermodynamic and dynamic fields are appropriately adjusted by model integration posterior to data assimilation. The statistics of 17 track forecasts for typhoon Hagupit (2020) also show the positive effect of RO data assimilation. A forecast sample reveals that the member with RO data assimilation simulates better typhoon structure and intensity than the member without, and the effect can be larger and faster via multi-cycle RO data assimilation.

Automatic Laser Monitoring for Dam Safety

2005 ◽  
Vol 295-296 ◽  
pp. 239-244
Author(s):  
K.D. Yue ◽  
X. Zhou ◽  
J. Gao
Keyword(s):  
Data Transmission ◽  
Can Bus ◽  
Arch Dam ◽  
Dam Safety ◽  
Monitoring Methods ◽  
Long Distance ◽  
Dam Safety Monitoring ◽  
Distance Data ◽  
Data Transmission System ◽  
Laser Monitoring

Many monitoring methods for dam safety have been proposed in recent years but it is difficult to monitor the arch dam automatically. A novel inspecting method for arch dam safety monitoring is described in this paper. This measurement system is based on the principle of transmitting the comparative displacement one by one. The error and accuracy of the system is analyzed. By this method, a large arch dam can be measured automatically. Long distance data transmission system using CAN bus and Internet is established. It is convenient to monitor the safety of dams from long distances.

Reasonable Strength Criterion Research of High Arch Dam Based on Brittle Failure Constitutive Relation

2014 ◽  
Vol 578-579 ◽  
pp. 964-967
Author(s):  
Zhi Qiang Wang ◽  
Wen Biao Liu
Keyword(s):  
Constitutive Relation ◽  
Brittle Failure ◽  
Concrete Strength ◽  
Safety Evaluation ◽  
Strength Criterion ◽  
Arch Dam ◽  
Dam Failure ◽  
Dam Safety ◽  
High Arch Dam ◽  
Triaxial Strength

The brittle failure finite element method is widely used in arch dam safety evaluation, but it also has some problems, the concrete strength criterion is different, the dam failure range is different. This article first introduces brittle failure constitutive relation and three strength criterions, then takes a high arch dam as an example to compute, obtains some conclusions that the relative failure range of foundation plane corresponds to blaxial strength criterion is slightly bigger than the result of uniaxial strength criterion, is almost the same as the result of triaxial strength criterion. Because the influence of the third principal stress is compressed stress to the dam crack is taken into account under multiaxial strength criterion, therefore using multiaxial strength criterion is more reasonable.

scholarly journals Failure of Zoned Earth Dam (An analysis of earth dam break)

2019 ◽  
Vol 27 (1) ◽  
pp. 344-353
Author(s):  
Abdul-Hassan K. Al-Shukur ◽  
Ranya Badea’ Mahmoud
Keyword(s):  
Water Level ◽  
Factor Of Safety ◽  
Limit Equilibrium ◽  
Water Flux ◽  
Dam Break ◽  
The Body ◽  
Earth Dam ◽  
Dam Failure ◽  
Maximum Water Level ◽  
Maximum Water

One of the most common type of embankment dam failure is the dam-break due to overtopping. In this study, the finite elements method has been used to analyze seepage and limit equilibrium method to study stability of the body of an earthfill dam during the flood condition. For this purpose, the software Geostudio 2012 is used through its subprograms SEEP/W and SLOPE/W. Al-Adhaim dam in Iraq has been chosen to analysis the 5 days of flood. It was found that the water flux of seepage during the flood reaches about 8.772*10-5. m3/sec when the water level 146.5 m at 2nd day. Seepage through the embankment at maximum water level increased by 55.1 % from maximum water level. It was concluded that the factor of safety against sliding in downstream side decrease with increasing water level and vice versa. It was also concluded that the deposits are getting more critical stability during the conditions of flood when the factor of safety value reaches 1.219 at 2nd day.

Study on Hydraulic Characteristics and Optimization of Siphon Channel with Two Inlets in Drydock

2014 ◽  
Vol 638-640 ◽  
pp. 1285-1292
Author(s):  
Peng Zhao ◽  
Yu Chuan Bai
Keyword(s):  
Energy Dissipation ◽  
Numerical Model ◽  
Kinetic Energy ◽  
Dissipation Rate ◽  
Three Dimensional ◽  
Flow State ◽  
Hydraulic Characteristics ◽  
Channel System ◽  
Guide Wall ◽  
Low Efficiency

Compared with the siphon channel with one inlet, the siphon channel with two inlets has some problems such as low efficiency of flooding. Combining with the model test of siphon channel with two inlets in a drydock, three-dimensional numerical model was built to study the hydraulic characteristics of siphon channel system. The reliability of numerical model was confirmed by comparing the calculated value and measured value of hump pressure and flooding rate. Results of turbulent kinetic energy and dissipation rate indicate that flow kinetic energy is mainly dissipated by the friction and its impacting the wall behind partition and the effect of energy dissipation pillars are not obvious. By comparing flow state in front of energy dissipation section and flooding rate between design scheme and modified scheme, it is suggested that the guide wall should be dismantled to ameliorate flow state.

Thermal Cycling Simulation during Remelting Process of the Steel ASTM A743-CA6NM

2014 ◽  
Vol 1082 ◽  
pp. 100-105
Author(s):  
Camila Almeida Martins ◽  
Jhon Jairo Ramirez-Behainne
Keyword(s):  
Numerical Model ◽  
Thermal Cycling ◽  
Material Properties ◽  
Three Dimensional ◽  
Fusion Line ◽  
Maximum Deviation ◽  
Experimental Measurements ◽  
Ansys Fluent ◽  
Simplifying Assumptions ◽  
Volume Method

This study aimed to model numerically the thermal cycling resulting from the steel ASTM A743-CA6NM remelting process. The problem was solved with the support of the commercial software ANSYS / FLUENT ® 14.5 for the three-dimensional case using the finite volume method. The following simplifying assumptions were adopted: heat loss by natural convection, absence of radiation, no phase change, concentrated heat source, and thermophysical properties independent of temperature. The results were analyzed for two different current intensities: 90A and 130A, and compared with experimental measurements. The peak temperatures of the thermocouples near the fusion line for the current of 130A were well represented by the numerical model, with a maximum deviation of 9.62%. In the case of the more remote thermocouples from the fusion line, the best results were obtained for the current of 90A, not exceeding 5% of deviation. In general, it was found that the tested body is heated faster than in simulations. This can be considered as a consequence of the simplification in material properties, which were assumed constants with temperature. The results of this study demonstrate that, given the adopted simplifications, the numerical model was able to satisfactorily reproduce the experimentally measured thermal cycles.

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