Hydrodynamic and morphodynamic responses to surfzone seafloor perturbations
MetadataShow full item record
Holes and channels were excavated in the surf zone on an ocean beach near Duck, NC, and observations of the subsequent evolution of waves, currents, and the modified seafloor were used to investigate nearshore dynamics. In one set of seafloor perturbation experiments, deep holes with steeply sloping sides were excavated in the inner surfzone seafloor. Observations of the infilling holes were used to make the first field estimates of the surfzone morphological diffusivity, which describes the rate of seafloor smoothing by downslope sediment transport. To improve the temporal resolution of bathymetric estimates, a mapping method was developed to combine infrequent, spatially dense watercraft surveys with continuous, spatially sparse in situ altimeter estimates of the seafloor location. In another set of seafloor perturbation experiments, channels were dredged across the surf zone with the propellers of a landing craft. Alongshore variations in wave breaking caused by the perturbed bathymetry resulted in strong rip currents in the channels under some conditions, whereas alongshore currents bypassed the channels under other conditions. The dynamics of the circulation response for changing wave forcing, bathymetry, and tidal elevation are investigated using the observations, a numerical model, and a parameter based on wave properties and bathymetry.
Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution June 2016
Showing items related by title, author, creator and subject.
Bohlen, Walter Franklin (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1969-08)A series of laboratory experiments were performed to ascertain the extent and manner of turbulence modification induced by low concentration suspended loads of near neutral buoyancy. Hot-wire measurements of the fluid ...
Tapscott, Susan Schultz (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1975-09)An experimental investigation of the tangentiaì drag of an axially oscillating cylinder is presented. Deep-sea mooring cables are oscillated sinusoidally at ocean wave amplitudes and frequencies, and experimenta1 values ...
Geiger, Sam R. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2000-09)A finite difference computer model is developed to simulate the exposure statistics of a radio frequency buoyant antenna as it is towed in a three-dimensional random seaway. The model allows the user to prescribe antenna ...