Hydrodynamics and sediment transport in the inner surf and swash zones

Hydrodynamic and morphodynamic processes occurring in the swash zone control the erosional and accretional patterns of the foreshore, the last line of natural defense for the backbeach from the full brunt of ocean waves. Our study focuses on inner surf and swash motions through remote sensing, field data collection, and numerical modeling efforts. Data obtained from these endeavors are used to better predict and understand sediment transport in this region, through modeling efforts and through kinematic and statistical relationships.; The first portion of this dissertation provides a thorough background on the studies that have been undertaken in the swash zone in the last few decades. Following this review, several field studies are explored with the aim to better predict sediment transport, specifically erosion, on the foreshore. Initially, flow velocity and suspended sediment concentration (SSC) measurements are used to show that SSC depends on both fluid velocity and fluid acceleration leading to an additional term in a typically used sediment transport formulation. However, it is proposed that the inclusion of this term, while being a function of acceleration, likely serves as some parameterization for the turbulence generated in the bore. Armed with this new formulation, an experiment was carried out to further validate an optical remote sensing technique for estimating the surface fluid velocities in the swash zone over a large spatial region that could be used in a three-dimensional model of sediment transport and foreshore change. We found that the formulations with an acceleration term increased the predictive skill of the beach change, while at the same time reducing the error between the predicted and true bathymetry.; Finally, we focused on high resolution numerical modeling of inner surf and swash zone hydrodynamics over a fixed bed. The model solves the Navier-Stokes equations, and is able to accurately reproduce the sea surface elevation and fluid velocities across the inner surf and swash zones, in addition to giving detailed information on pressure gradients and bed shear stress.