Journal of Waterway, Port, Coastal, and Ocean Engineering

To better understand the effects of river flow and tidal stage on the propagation of realistic tsunami waves up large rivers, simulations of the Columbia River (United States) were carried out. The two-dimensional depth-averaged version of the advanced circulation model was used. The model was forced with open boundary tides, tidal potential, and river flow. Simulations without tsunami waves demonstrated excellent agreement with numerous tidal gauging stations in the domain. A Cascadia Subduction Zone earthquake and associated tsunami were then considered by prescribing a rapid temporal change in the bathymetric/topographic grid. The simulations were repeated over a wide range of river flow conditions and a wide range of tidal phases. In each simulation, the tsunami was characterized in terms of the variation of its amplitude with upriver distance, how much land was inundated, and its propagation speed up the estuary. Although river flow is a dominant mechanism in the Columbia River in terms of stratification and surface currents, it was found to have only a minor effect on the propagation and inundation of the tsunami. The effect of tidal phase was more pronounced and more complex.

Several instruments using different technologies are available for the survey and characterization of underwater mud deposits. This paper is concerned with an instrument that uses tuning fork technology to estimate mud density in the field. A model explaining how the tuning fork operates and how it can be used to measure mud properties is presented. In this model, the tuning fork is represented as a damped harmonic oscillator, and the mud is considered a viscoelastic medium showing an elastic response for small deformations and a viscous response for large deformations. The model clearly shows that the tuning fork must be calibrated for the local mud at each survey location. This was confirmed during surveys at the Amazon estuary and the Río de la Plata during 2011 and 2012. The measurements obtained during these surveys are compared with measurements performed with optical and acoustic instruments with very good results.

A mathematical model of the transport of dredging-induced turbidity in the far field was developed in this study. Unlike the majority of the existing models, which assume a steady state, the present model retains the transient term, $\partial c/\partial t$, to predict the temporal evolution of the spatial extent and concentration of the sediment plume. The unknown source strength is calibrated using field data. The appropriate turbulent diffusion coefficient in the longitudinal direction, $D_x$, is set to comply with the real situation with negligible longitudinal diffusion. The complete transient model formulation was then used to analyze the effects of key modeling parameters, such as the water depth, $h$, mean tidal current velocity, $u$, turbulent diffusion coefficients in the longitudinal and transverse directions, $D_x$ and $D_y$, as well as the sediment-settling velocity, $w_s$, on the model prediction, in particular the approach to the steady state and the ultimate suspended sediment concentration level at the steady state. The semianalytical model thus developed with improved functionality can be used for worst-case assessments of the steady-state flow conditions in the far-field transport of the sediment plume generated by dredging operations.

This paper presents a concept of data-driven beach equilibrium profiles of cross-shore seabed records from the coastal station of Instytut Budownictwa Wodnego Polskiej Akademii Nauk at Lubiatowo, Poland, where multiple longshore bars are present. Data-driven equilibrium profiles are the monotonic trends of cross-shore seabed profiles. They were extracted using the empirical mode decomposition method. They retain general properties of Dean profiles, i.e., the Dean coefficients fitted to raw profiles are practically identical to those fitted to their trends. The monotonic property of trends allows for the introduction of cross-shore variable wave-energy dissipation rates, which can be compared with the constant Dean rates. This is the novel element of data-driven beach equilibrium profiles. Variable rates help indicate locations on a beach where wave-energy dissipation is intensive and produces erosion and where it is lower and generates deposition of sediment. In other words, variations of wave-energy dissipation can be assessed with greater precision from seabed configuration only, without any hydrodynamic information. Importantly, when a local wave climate is known, the associated depths of closure can be evaluated to determine the offshore limits, where the data-driven beach equilibrium profile concept can be valid.

The phase-averaged wave model Simulating WAves Nearshore (SWAN) is often used for the design of dikes and harbors. However, various hindcast studies have shown that SWAN underpredicts the wave energy when waves are penetrating into bathymetries with shallow areas traversed by channels, such as tidal inlets or harbor entrances. The underprediction of these waves could lead to dike failure or shipping downtime as a consequence of incorrect hydraulic loads. This paper presents an explanation for the underprediction of this wave penetration. By comparing a series of SWAN computations with laboratory measurements and computations with the Boussinesq-type wave model TRITON, it is demonstrated that the absence of various subharmonic and superharmonic interactions in SWAN causes an unrealistic amount of energy to be trapped on the channel slopes owing to wave refraction. The two-dimensional nonlinear interactions, which appear to be present in the measurements and TRITON results, broaden the directional range of the energy density spectrum when waves propagate over a sloping bottom. Owing to the directional broadening of the spectrum, more energy exists at angles smaller than the frequency-dependent critical angle for refraction, and therefore more wave energy is transmitted into and across channels, especially when waves approach the channel under an angle. It is recommended that this insight be used to find an alternative formulation for the present one-dimensional three-wave interaction formulation in SWAN.

Impulse waves are generated by avalanches, landslides, rock slides, rock falls, or glacier calving impact into natural lakes or reservoirs. Similar to tsunamis, the generated long waves imply a large damage potential to the surrounding infrastructure and settlements. The current hazard assessment is mainly limited to plane wave run-up because previous studies were related to linearly inclined slopes. The presented study therefore focuses on solitary impulse wave–induced overland flow on a horizontal shore. Physical experiments involved a two-dimensional test setup in a wave channel including a piston-type wave generator and an inclined shore with a connected horizontal overland flow plane. Particular focus is given to the transition from the inclined to the horizontal portion, where the orbital wave motion is transformed into a shore-parallel flow. The overland flow features were investigated by means of ultrasonic distance sensors and particle image velocimetry for various values of relative wave height, shore slope, and freeboard. Prediction equations are specified for the maximum flow depths, flow velocities, and the maximum discharge.