(9) Determining Fluvial Flow Conditions from Bed Set Geometry

From Stratodynamics


Robert Mahon & Brandon McElroy

Affiliation: Department of Geology & Geophysics University of Wyoming

Contact: bmcelroy@uwyo.edu


The sedimentary record provides many opportunities to recreatepast environmental conditions. The geometry of fluvial strata isone of the promising new avenues for estimating paleo-flowhydraulics and morphodynamic conditions. Sandy beds evolvestochastically, and as a result their dynamics are appropriatelycaptured by a kinematic wave equation with a source-sink term.In essence the source sink term represents all of the topographicchanges to a bed in its Lagrangian reference frame and is termeddeformation. Deformation gradients are dimensionally consistentwith the curvature of set boundaries. In order to use this relation to determine hydraulic conditions, the dependence ofdeformation on sediment hydrodynamics must be resolved. We hypothesize that deformation is a function of Rouse number suchthat it is maximized within the stability field for dunes. This will be explored and tested with a series of laboratoryexperiments recording hydraulics, sediment dynamics, bedevolution, and resultant stratigraphy. These results will provide a new tool for extracting past environmental conditionsfrom ancient fluvial deposits.