On the importance of grain density to modeling bedload transport of carbonate sediment on coral reefs

Kurt J Rosenberger, USGS, Coastal and Marine Geology, Baltimore, MD, United States, Curt Daron Storlazzi, US Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, United States, Olivia M Cheriton, USGS Pacific Coastal and Marine Science Center, Santa Cruz, CA, United States, Andrew William Mackay Pomeroy, University of Western Australia, The UWA Oceans Institute, Crawley, WA, Australia, Jeff Hansen, University of Western Australia, Crawley, WA, Australia and Michael Cuttler, The University of Western Australia, Oceans Graduate School and UWA Oceans Institute, Perth, WA, Australia
Abstract:
Carbonate reefs are a major source of sediment for coastlines in many tropical regions of the world, making significant contribution to shoreline maintenance. There has been a recent focus on the importance of reefs to protecting shorelines and understanding the mechanisms by which carbonate sediment reaches the coast. Field observations indicate that bedload transport can be an important contributor to the overall flux of sediment to the shoreline in these environs. Several models of ripple formation and migration incorporate the non-dimensional grainsize, D*, in their formulations, which includes the grain density of the sediment. Carbonate sediment typically has a lower grain density than quartz beach sediment (up to 30% less). As such, models that use a quartz density can overestimate ripple amplitudes and wavelengths, leading to an overestimate of total bedload transport in carbonate reef environments. Here we compare field observations of ripple formation and migration to several models of equilibrium ripple dimensions (Wiberg and Harris, 1994, Styles and Glenn, 2002 and O’Donoghue, 2005) to evaluate which formulation best estimates the properties of bedforms on a fringing coral reef in Ningaloo, Australia.
Back to: Connections Between Coral Reef State, Physical Processes, and Coastlines II Posters