HR: 1330h
AN: OS52A-0901    [PDF]
TI: Stratigraphic Variability Due To Uncertainty In Model Boundary Conditions
AU: * Overeem, I
EM: irina.overeem@colorado.edu
AF: Environmental Computationa and Imaging Facility, INSTAAR, University of Colorado campusbox 450, Boulder, CO 80309-0450 United States
AU: Syvitski, J P
EM: james.syvitski@colorado.edu
AF: Environmental Computationa and Imaging Facility, INSTAAR, University of Colorado campusbox 450, Boulder, CO 80309-0450 United States
AB: Uncertain boundary conditions influence the predictions of numerical sedimentary models, especially over geological timescales. This study explores the effects of uncertainty in a number of complex climatological boundary conditions on the stratigraphic prediction. Two high-resolution models are sequentially run: the climate-driven hydrological model, HydroTrend, generates time series of daily discharge and sediment loads at the river mouth, which are then ingested in the process-based stratigraphic model, 2D-SedFlux. Focus is on shallow shelf evolution over the last 21kyr; both for the East Coast US and for two Italian margins sites at Sicily and Elba respectively. Considerable uncertainty is associated with the input parameters. Drainage basin characteristics are strongly controlled by the hard to define details in the timing of Ice Sheet retreat. Temperature and precipitation at 21kBP estimates differ significantly between different Community Climate Model (CCM) realizations. The translation of a proxy for ocean storm conditions to storm diffusivity in SedFlux is a tuning process and thus requires a wide range of values. A first case-study showed that the SedFlux prediction for the sedimentary architecture of the New Jersey shelf is consistent with the acoustically observed thickness distributions and facies. Sensitivity tests that explore the ranges in the input parameters show local deviations in the thickness distribution of up to 46%, considerable depth variation ($>$10m) in the prediction of certain facies shifts and up to 1.5” difference in the mean grain size prediction. We propose to associate a standard deviation, as well as a data-sparse PDF based on a series of sensitivity experiments to a predicted `base-case' value. In that way the stratigraphic variability caused by ranges in the boundary conditions is evident for later users.
UR: http://instaar.colorado.edu/deltaforce/
DE: 1620 Climate dynamics (3309)
DE: 3020 Littoral processes
DE: 3022 Marine sediments--processes and transport
DE: 3099 General or miscellaneous
DE: 3210 Modeling
SC: Ocean Sciences [OS]
MN: 2003 Fall Meeting