Estimating Aeolian Creep Transport Rates
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Keywords: Wind-blown sand, mass flux profiles, exponential curves
Abstract Type: Paper Abstract
Authors:
Douglas Sherman, University of Alabama
Ascanio Araujo, Federal University of Ceara
Pei Zhang, Texas A&M University
Jean Ellis, University of South Carolina
Jinsu Bae, University of Alabama
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Abstract
Aeolian creep transport, defined as comprising the population of sand grains moving on or near the bed, is typically considered to represent about 25% of total transport. Recent research indicates that the proportion of creep is often much less, with at least three papers reporting average creep rates of less than 10%, and sometimes less than 5%. The discrepancy is important because these values are used to estimate total transport rates based on saltation measurements made at elevations at 0.1 m or more above the bed. In this paper we report the results from field experiments conducted in the Sonoran and Mojave deserts in California and near Jericoacoara, in Ceára State, Brazil, representing six different transport environments.
Wind speeds were measured at elevations about 0.5 m above the bed with an ultrasonic anemometer. Those data were used to derive Reynolds stress estimates of shear velocity. Profiles of sand flux were measured at multiple elevations from the sand surface to heights of about 0.4 m above the bed. Exponential curves were fit to the data. Creep transport was estimated using the method of Horikawa and Shen (1960), comparing measured, near-bed sand masses to those predicted by the exponential flux profile characterizations. The differences between the two represent creep transport. Results of that analysis are reported in this paper.
Estimating Aeolian Creep Transport Rates
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Paper Abstract