HR: 0800h
AN: H41B-0494    [Abstracts]
TI: Field and Laboratory Investigations of Coastal Dune Morphodynamics
AU: * Ruggiero, P
EM: ruggierp@geo.oregonstate.edu
AF: Oregon State University, Department of Geosciences, 104 Wilkinson Hall, Corvallis, OR 97331, United States
AU: Maddux, T
EM: tbmaddux@engr.orst.edu
AF: Oregon State University, O.H. Hinsdale Wave Research Laboratory, Corvallis, OR 97331, United States
AU: Kaminsky, G
EM: gkam461@ecy.wa.gov
AF: Washington Department of Ecology, 300 Desmond Drive, P.O. Box 47600, Olympia, WA 47600, United States
AU: Palmsten, M
EM: mpalmste@coas.oregonstate.edu
AF: Oregon State University, College of Oceanic and Atmospheric Sciences 104 COAS Admin Bldg, Corvallis, OR 97331, United States
AU: Holman, R
EM: holman@coas.oregonstate.edu
AF: Oregon State University, College of Oceanic and Atmospheric Sciences 104 COAS Admin Bldg, Corvallis, OR 97331, United States
AU: Cox, D
EM: dan.cox@oregonstate.edu
AF: Oregon State University, O.H. Hinsdale Wave Research Laboratory, Corvallis, OR 97331, United States
AB: Coastal dunes are important features along many coastlines, owing to their role in sediment budgets, their use as ecologically unique habitat, and their ability to protect onshore resources from wave attack. Skillful predictions of the erosion and overtopping rates of these features are needed to quantify coastal vulnerability during major storm events. Knowledge of post-storm recovery and subsequent dune growth rates is critical to developing quantitative sediment budgets and ultimately for predicting future shoreline positions. We have been conducting both long-term field and large-scale laboratory studies to improve our understanding of dune morphodynamics and will present results of dune behavior, including various feedback mechanisms, at scales ranging from individual storm events to decadal trends. A large-scale physical model study of dune erosion was recently performed at Oregon State University's O.H. Hinsdale Wave Research Laboratory producing a comprehensive, near prototype-scale data set of hydrodynamics, sediment transport, and morphological evolution during extreme dune erosion events. The laboratory moveable bed beach/dune system was brought to equilibrium with pre-storm random wave conditions. It was subsequently subjected to attack from steadily increasing water levels and offshore wave heights simulating a natural storm surge hydrograph. Observations made include inner surf zone and swash free surface and velocities as well as wave-by-wave estimates of topographical change at high spatial resolution through the use of stereo video imagery. Initial results suggest strong feedbacks between the evolution of the foreshore profile during the storm and episodic dune slumping events. Beach topographic data have been collected quarterly along southwest Washington and northwest Oregon since 1997 resolving the seasonal to interannual morphological variability of a nearly 160-km long high-energy dissipative coastline. Major climate events (such as El Ninos) cause region-wide dune erosion/scarping due to high water levels and increased storminess. However, subsequent dune recovery rates have been variable and appear linked to variations in short-term shoreline change rates and sediment budgets. At interannual scale regions of high shoreline progradation rates experience relatively high dune growth rates. At longer time scales, overall dune morphology is again linked to shoreline change rates but with the highest foredune ridges occurring in areas of relative stable shorelines at decadal scale.
DE: 1824 Geomorphology: general (1625)
DE: 3022 Marine sediments: processes and transport
DE: 4217 Coastal processes
DE: 4546 Nearshore processes
DE: 4558 Sediment transport (1862)
SC: Hydrology [H]
MN: 2007 Fall Meeting