HR: 13:55h
AN: OS13B-02 INVITED    [Abstracts]
TI: Some Uncertainties in the Inversion of Sediment Deposits to an Incident Tsunami Waveform
AU: * Lynett, P
EM: plynett@tamu.edu
AF: Texas A&M University, Department of Civil Engineering, College Station, TX 77843,
AB: This presentation will present a numerical inversion of the deposit data from a recent and pre-historic tsunami using a coupled hydrodynamic-sediment transport model. The hydrodynamic model uses an established nearshore wave evolution scheme, and includes breaking and bottom friction dissipation. The sediment transport module includes both bed and suspended loads, and is driven by a Shields-type bottom flux condition. Multiple grain sizes can be approximated. Through an iterative technique, an incident tsunami time series is created which represents an optimum match with the recorded deposit data. The resulting incident time series is dependent on a large number of assumed parameters. For the physical beach these include (but are not limited to): pre-tsunami beach profile, regions of erodible bottom, and initial distribution of the sediment source. The bottom type is also an important parameter, and will be discussed in terms of a bottom friction coefficient. The modeling itself also brings a level of uncertainty to the inversion. Most significant is the method used to entrain sediment; namely its applicability to a highly unsteady flow. All of these parameters will be varied, and the impact measured. It is the goal of this work to assist in the identification of the most important variables that can be measured in the field, as well as modeling aspects that should be improved.
DE: 4534 Hydrodynamic modeling
DE: 4546 Nearshore processes
DE: 4558 Sediment transport (1862)
DE: 4564 Tsunamis and storm surges
SC: Ocean Sciences [OS]
MN: 2007 Fall Meeting