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The overtopping process, resulting from landslide-induced waves, has the potential to cause significant damage to downstream infrastructures. To minimize the associated losses, it is essential to study the overtopping phenomenon. Limited research has been conducted on physical modeling and volumetric calculation of wave overtopping in reservoirs with arch dams. The study designed a physical model experiment at a geometric scale of 1∶70 to investigate the occurrence of wave overtopping caused by landslides in arch dam reservoir areas at the maximum water depth scenario. Equations developed for straight dams, such as gravity dams, overestimate the volume of overtopping caused by landslides in arch dam reservoirs due to structural dissimilarities. Two volumetric overtopping equations specifically applicable to arch dams were derived through regression analysis. Additionally, the analysis of model experimental data unveiled the distribution pattern of the initial wave amplitude along the dam face, the overtopping duration characteristics, as well as the factors influencing the volume of overtopping. The underlying causes of these phenomena are explained in this paper. This study offers valuable insights into comprehending the intricate process of wave overtopping generated by landslides. These insights encompass the estimation of overtopping volume, as well as the safety assessment of downstream. [ABSTRACT FROM AUTHOR]

Physical experiments were conducted in an impounded channel to study the propagation of negative surges advancing in still water and evolution of undular surges against an instantaneously varied flow. The results demonstrated that the initial wave height of a negative surge could be accurately predicted using the simple wave solution of the Saint–Venant equations. Moreover, the wave height evolution during surge propagation could be satisfactorily described using the solution by Ippen and Kulin. The main characteristics of an undular surge were strongly correlated to the surge Froude number and turbulent boundary layer development at the toe of the surge. However, the occurrence of wave breaking at the first wave crest was independent of the inflow conditions and was close to the breaking criterion for solitary waves. Furthermore, the present results indicated the largest turbulent Reynolds stress components beneath the wave crests of an undular surge. [ABSTRACT FROM AUTHOR]

The depths and areas of the scour holes around spur dikes are the most concerning issues regarding spur dike design. In this study, using a moving bed experiment, the influence of traditional rock-fill spur dikes and new permeable spur dikes with different permeabilities on riverbed scour under unsteady flow was studied, and the spatial characteristics of scour holes at dike heads were analyzed. The results show that with increases in the permeability coefficient of the spur dike, the depth and area of the scour hole at the dike head gradually decreases; however, when the permeability coefficient is more than 17.6%, the depth and area of the scour hole downstream of the dike body increases with an increase in the permeability coefficient. According to comprehensive evaluation, when the water permeability is 17.6%, the stability of the spur dike is at its best. The maximum depth of the scour hole at the dike head is affected by factors such as the spur dike permeability coefficient, effective scouring time, and width bottom protection structure. On this basis, a new formula for calculating the maximum depth of the scour hole at a dike head is proposed. These research results will be beneficial to the reliability of spur dikes and the sustainability of navigation channels. [ABSTRACT FROM AUTHOR]

Bank slopes are an important part of river ecosystems. In recent years, a series of ecological engineering projects with ecological functions have been implemented in the middle and lower reaches of the Yangtze River. In this study, we designed a new type of ecological slope-protection structure for rivers. Through physical model tests, the hydraulic characteristics of the structure, such as velocity, turbulence intensity, and Reynolds stress, at different test conditions were analyzed. These characteristics were then compared with those of an open channel with vegetation. The distributions of hydraulic properties determined in the open-channel tests involving the new structure were similar for different experimental conditions. Velocity and turbulence intensity are hyperbolic along the normal direction, whereas the Reynolds stress is close to zero. Several inflection points were observed in each distribution of hydraulic properties. The inflection point at the top is due to variations in the water flow conditions. On the outside, a second inflection point occurs because the water flow fluctuates violently near the new structure. The distribution of hydraulic properties in the far water layer is similar to that observed in a soft bed test. This study provides foundational knowledge for the future development of ecological slope-protection structures. A new ecological slope-protection structure is proposed. The distribution of hydraulic characteristics of an open channel with the new structure is analyzed. The zoning of shore slopes for the construction of the new structure is presented. The hydraulic characteristics of an open channel with the new structure and of an open channel with vegetation are compared. [ABSTRACT FROM AUTHOR]

Physical experiments were conducted in a long water wave tank over a wide range of still water depths to study the evolution and runup of nonbreaking undular surges generated by the release of a given volume of water. The results demonstrated that the wavefront of a nonbreaking undular surge closely matched that of the corresponding solitary wave of the same height. The wave celerity of the surge could be accurately predicted using the solitary wave theory. Two distinct wave stages existed in the evolution process of a nonbreaking undular surge based on the wave shape asymmetry. The wave stage transition could be approximated as a surge Froude number equal to 1.15. The wave amplitude and steepness of undular surges were in reasonable agreement with the linear wave theory for surge Froude numbers greater than 1.20. However, the wave length data presented a different pattern to that predicted by either the linear wave theory or the solution of the Boussinesq equation. Furthermore, the maximum surge runup on a vertical wall was in excellent agreement with the solitary wave theory. This study provided new insights into the quantitative behavior of nonbreaking undular surges. [ABSTRACT FROM AUTHOR]

The results are presented from a laboratory and theoretical study to investigate the effects of sediment concentration and initial phosphorus loading on adsorption isotherm and capacity. The tested aquatic sediment was collected from the Chongqing reach of the Yangtze River. The adsorption isotherm of dissolved phosphate was approximated by the Langmuir equation. Using mass conservation and Langmuir adsorption kinetic equations, the authors derived formulas for calculating both the particulate and dissolved phosphate concentration. Kinetic experiments on fine sediment samples ( CE Database subject headings: Adsorption; Phosphorus; Sediment; Concentration; Experimentation; China; Rivers.

Results are presented to investigate the characteristics of turbulent flow in a pressure conduit, such as water supply pipes and flood discharging tunnels. The turbulent flow governing equations, the Reynolds-averaged Navier-Stokes equations, in conjunction with a k-[epsilon] turbulent model are numerically solved using SIMPLEC. The study focuses on the modeling and calculation of the flow velocity field, pressure distribution, and the incipient cavitation number of the surface irregularities in the conduit. Different types and sizes of irregularities are simulated for various incoming flow velocities. The computed results are in good agreement with laboratory experimental data. DOI: 10.1061/(ASCE)0733-9429(2007)133:6(698) CE Database subject headings: Numerical models; Cavitation; Turbulent flow; Pressure distribution; Pressure pipes; Pipe flow.

Impulse waves generated by landslides lead to serious secondary disasters. To investigate the effects of impulse waves on a bank slope, a three-dimensional physical model test was conducted considering multiple factors, such as the width, thickness, and volume of the landslide body, inclination angle of the landslide, and bank slope angle. The results show that the wave did not break upon the first crest. And the waves break and swirl locally when fallback water flowed into the trough. The pressure acting upon the bank slope included pulsating pressure and impact pressure, of which the latter was largely affected by repeated tests, measuring frequencies, and measurement point densities. The existing empirical formulas cannot accurately reflect the wave pressure on the bank slope under the action of landslide-generated impulse waves. The maximum pulsating pressure increased proportionally with width, thickness, volume and inclination angle of the landslide body. This study better restores the interaction process between landslide, impulse waves and bank slope in actual river channels, and provides relevant support for the formulation of water pressure prediction formulas. [ABSTRACT FROM AUTHOR]