Sand Ripple Generation, Evolution and Decay: An Investigation of Physical and Biological Controls

The central goal of this research is a deeper understanding of bed state adjustment in mobile sandy sediments on the inner continental shelf, and in particular the adjustment(s) to the combined effects of variable fluid forcing and biological reworking of the sediment surface. The work is motivated by the lack of a suitable observational basis for developing and testing models of the temporal evolution of the seabed roughness spectrum resulting from fluid-sediment-biological interactions in environments subjected to transient wave forcing events. Our primary objective in this first phase of the project is to quantify the rates of ripple degradation and seabed roughness change arising from biological activity on and within the seafloor. The second objective is to compare the measured degradation rates to those predicted by analytic and numerical models of bed roughness change by biological organisms, as a function of spatial frequency spanning the ripple band.