Journal of Hydraulic Structures
Volume:9 Issue: 4, Winter 2023

Research on multi-dimensional aspects of dam engineering is gaining momentum because of massive flood destructions in lives, ecosystem and development including Wivenhoe dam flood in 2011, Oroville dam’s spillway incident 2017 and the Europe’s widespread flooding in 2021. The aim of this study is to capture and review research activities in dam science. A case study of the Wivenhoe dam Brisbane Australia, focusing on its design, catchment, water storage and flood mitigation capacity, management procedure, climate change and historical rainfall pattern has been carried out to conclude why such a catastrophic flood event happened in Brisbane in January 2011. Reviewed literatures throughout the world indicated that dam failures are primarily associated with improper design, inadequate monitoring in construction period and poor management (operational) practices. In the case of the Wivenhoe dam flood, the report of the Flood Commission of Inquiry Australia was that the dam was operated so that its flood mitigation was near optimal. Whilst the operators were found to be at fault for not following the Operation Manual, it was found that the manual was confusing and difficult to follow, and therefore, they were cleared of all liability. Hence, it is difficult to conclude what would have actually happened if the Wivenhoe dam operators had released more water earlier, author’s reasoned outlook about the flood mitigation measures used at the time is to ask the question “was reasonable discretion” used during the flood.

A large number of fires occur in offshore structures as a result of oil spill or earthquake. A potential but rarely examined risk is the sequential happening of fires and earthquakes. The high ignition temperature can have serious structural influences on the seismic behavior of dolphin-type berth structure. The fire induced structural effects on the seismic performance of Dolphin structure is not well unstated, but may be critical in the occurrence of aftershocks and/or future ground excitations. Considering the irreparable consequences of reducing the seismic performance of fixed marine structures under post-fire conditions, it is vital for engineers to better understand post- fire earthquake hazards in Dolphin structure. The current manuscript presents a numerical investigation to examine the influence of post-fire conditions on the seismic behavior of dolphin-type berth structure. the main goal of this paper is to investigate the effects of fire on the seismic response of the structure. In order to better investigate the effects of temperature increase on the performance of the structure, fire is applied in the first stage near the water surface and in the second stage to the berth deck. The ABAQUS software package is utilized to model and solve the problem.

Blockages in water supply systems can arise from diverse causes, leading to pollution, energy loss, and reduced system performance. Detecting and addressing these blockages is crucial for managing pressurized systems like water supply and pipe networks. Analyzing pressure signals is a common method for detecting defects, with transient pressure signals being particularly effective compared to steady-state signals. This study focuses on experimentally investigating the impact of extended blockages on pressure signal characteristics in viscoelastic pipelines within the time and frequency domains. Elastic blockages of varying lengths and diameters were used in a laboratory experimental model of a viscoelastic pipeline. The findings reveal that blockages cause changes in the pressure signal shape, resonance frequencies, and phase in different domains. These changes are more pronounced with longer and higher percentage blockages. Increasing blockage length amplifies phase shifts and wave reflections, with pressure increase delayed by damping. Higher blockage percentages induce phase shifts and amplitude reflections during transient flow. Transient flow intensity affects only amplitude, not phase, with more pronounced reflections at high intensity. Blockage location influences the distribution of phase and amplitude frequencies. Geometric changes induce phase shifts and alter amplitude frequencies, while hydraulic characteristics solely impact amplitude.

Most of the pollution of dams, lakes and even coastal water is related to their upstream bed. When floods and drifts occur, the pollutants in the bed are carried into these bodies of water. There are several factors that influence the rate at which these pollutants are emitted. Among these factors, the material and slope of the bed play a crucial role, yet they have not been thoroughly investigated until now. Therefore, this study aims to model this phenomenon and examine the aforementioned parameters using a Lagrangian numerical method. The numerical method developed is the Smoothed Particle Hydrodynamics (SPH). The flow consists of two phases, one phase is considered a Newtonian fluid while the other phase is considered a non-Newtonian fluid. Due to the momentum of the fluid and the sharp changes in the flow, turbulent flow is assumed, and by approximating and calculating the turbulent viscosity, its effects are considered in the modeling. In addition to the fluid motion equations, the concentration equation is also solved to calculate the emission rate. After validating the computational code, nine different cases are modeled and evaluated based on the bed material and the slope of the bed. The results show that the change in each of these parameters has a significant effect on the emission of pollutants.

Sedimentation due to gravitation is applied widely in water and wastewater treatment processes to remove suspended solids. This study outlines the effect of the inlet and baffle position on the removal efficiency of sedimentation tanks. Experiments were carried out based on the central composite design (CCD) methodology. Computational fluid dynamics (CFD) is used extensively to model and analyze complex issues related to hydraulic design, planning studies for future generating stations, civil maintenance, and supply efficiency. In this study, the effect of different conditions of inlet elevation, baffle’s distance from the inlet, and baffle height were investigated. Analysis of the obtained data with a CCD approach illustrated that the reduced quadratic model can predict the suspended solids removal with a coefficient of determination of R2 = 0.77. The results showed that the inappropriate position of the inlet and the baffle can have a negative effect on the efficiency of the sedimentation tank. The optimal values of inlet elevation, baffle distance, and baffle height were 0.87 m, 0.77 m, and 0.56 m respectively with 80.6% removal efficiency.

Weirs serve as fundamental structures for channeling excess flow from behind dams to downstream areas. In this study,a numerical,laboratory investigation was conducted to explore the impact of different base nose shapes installed under the outlet keys,varying Wi,Wo ratios on discharges ranging from 5 to 80 liters,second. For numerical simulation,the optimal number of cells for meshing was determined,and a suitable turbulence model was selected. The results demonstrated that the numerical model effectively simulated the laboratory sample with a high degree of accuracy. Furthermore,the numerical model closely approximated PKW for all parameters Q,H,and Cd when compared to the laboratory sample. The findings revealed that,in laboratory models with a maximum discharge area of 80 liters per second,the weir with Wi,Wo,1.2,a 285 mm valve exhibited the lowest value,whereas the weir with Wi,0.71,a 305 mm valve showed the highest,owing to the higher discharge in the input-output ratio. Additionally,as the ratio of flow head to H,P weir height increased,the discharge coefficient Cd decreased. In comparing the flow conditions in weirs with different base nose shapes,it was observed that the weir with a spindle nose shape outperformed the piano key weir with a flat,semi-cylindrical,and triangular base nose. The coefficient of discharge in PKW1.2S,PKW1.2TR weirs,compared to the PKW1.20 weir,increased by 27%,20%,respectively.