Determining Fluvial Flow Conditions from Preserved Bed
Set Geometry
Robert C. Mahon and Brandon Mcelroy
University of Wyoming Department of Geology and
Geophysics, Laramie, WY
The downstream movement of bedforms in flowing water can be described as the combination of two
components: bed
form translation and
bed
form deformation. Previous work hypothesizes that
deformation (change in shape) of
bed
topography is primarily a function of the suspended portion of
bed
material load. However, a complete experimental determination of the physical conditions resulting
in
bed
deformation remains to be presented. This study will focus on the hypothesis that the ability of
flow to suspend sediment, best characterized by the Rouse parameter, provides a primary control on
the sediment bypass fraction at the
bed
form scale and therefore on rates and fluxes of
bed
deformation. A set of laboratory flume experiments will be conducted with migrating dunes on a natural
sand
bed
to test this hypothesis. A series of experimental runs will be undertaken to measure
bed
deformation rates over a range of Rouse number values, {0.5≤P≤4}. Furthermore,
bed
set stratigraphy
resulting from the migration of deforming
bed
forms will also be measured and a relationship between
deformation rates, flow parameters and the curvature of
bed
set bounding surfaces will be modeled.
These results have the potential for the development of new techniques by which indirect
measurements of
bed
material load can be calculated in natural sand-
bed
rivers, as well as a model
framework from which sediment hydrodynamics can be calculated from the curvature of preserved
bed
set bounding surfaces (shown to be the result of
bed
deformation) in the stratigraphic record.
AAPG Search and Discovery Article #90181©2013 AAPG/SEG Rocky Mountain Rendezvous, University of Wyoming, Laramie, Wyoming, September 27-30, 2013