HR: 16:00h
AN: H44D-01 INVITED     [Abstracts]
TI: Coupling Fluvial Incision, Delta Deposition, and Coastal Processes on Continental Shelves During Sea-Level Cycles
AU: * Fagherazzi, S
EM: sergio@csit.fsu.edu
AF: Department of Geological Sciences and School of Computational Science, Florida State University, Tallahassee, FL 32306-4120 United States
AU: Howard, A D
EM: ah6p@virginia.edu
AF: Department of Environmental Sciences, University of Virginia, Charlottesville, VA 22904-4123 United States
AU: Wiberg, P L
EM: pw3c@virginia.edu
AF: Department of Environmental Sciences, University of Virginia, Charlottesville, VA 22904-4123 United States
AB: We have coupled a numerical model that predicts the evolution and degree of incision and deposition by fluvial channels on the continental shelf with a coastal processes module. The coastal processes module is based on an asymmetric diffusion that mimics the effects of directional waves in the nearshore area at the geological timescale. Sediments are moved with a diffusion-like equation until a new cross-shore equilibrium configuration is reached. The model is based on the concept of equilibrium beach profile proposed by Bruun (1962) and Dean (1991). Preliminary results show that coastal processes partly erase the bathymetry of the inner shelf during sea-level rise. If the amount of sediment moved by waves and currents increases due to an increase of wave action (in the model the wave action is embedded in the coefficient of asymmetric diffusion) the nearshore bathymetry flattens, deleting fluvial deposits and old fluvial incisions. At the same time sediment reworking at the shoreline creates a series of barrier islands and a steep beach strand, both typical features of wave dominated coasts with abundant sediment sources. Waves reaching the shoreline with an angle less than 90 degrees do not seem to change the location of the fluvial deposits on the shelf. The inclination of the wave direction has instead a localized and transient effect on the geometry of the delta. More simulations indicate the effect of coastal processes on the erasure or burial of fluvial incisions during sea level cycles.
UR: http://www.gly.fsu.edu/~fagherazzi
DE: 1825 Geomorphology: fluvial (1625)
DE: 3022 Marine sediments: processes and transport
DE: 3045 Seafloor morphology, geology, and geophysics
DE: 4217 Coastal processes
DE: 4562 Topographic/bathymetric interactions
SC: Hydrology [H]
MN: Fall Meeting 2005