Predicting Aeolian Sand Transport Rates: A Sensitivity Analysis

Authors: Jean Ellis*, University of South Carolina, Dougals Sherman, University of Alabama
Topics: Coastal and Marine, Geomorphology
Keywords: aeolian geomorphology, sediment transport, saltation
Session Type: Paper
Day: 4/10/2018
Start / End Time: 2:40 PM / 4:20 PM
Room: Oakley, Sheraton, 4th Floor
Presentation File: No File Uploaded


As a community of aeolian researchers, we have been grappling with the perils associated with underperforming sand transport models for decades. We have been blaming poor model formulation and/or our measurement techniques for the discrepancies between measured and modeled mass transport (Q) values. In the last decade or so, formidable field studies have dissected equation components in an attempt to reach the Holy Grail-a perfect sand transport model. Here we deconstruct elements of these studies to ascertain the sensitivity of predictions to modest variability in the parameters that we believe control wind-blown sand transport rates. These parameters include: 1) beach/dune grain size; 2) A (from Bagnold’s u*t equation); 3) beach slope; 4) beach moisture; 5) ‘constants’ from the Q equations; 6) variability of u*; 7) air temperature; and 8) effective grain size. We assume wind measurements are made with a sonic anemometer, so we eliminate z0 and von Kármán’s ‘constant’. We will calculate the variability of Q using the ‘industry standards’ from the literature with the Lettau and Lettau (1978) Q model (as this has frequently been recognized as being the ‘best’) and by and varying each parameter by +/- 10 %. Through this exercise we can assess the relative sensitivity of model output to this degree of variability. We hypothesize that some of the variability will lead to negligible changes in predictions while others will demonstrate substantial influence on results. This assessment will help guide future efforts to improve our ability to model these aspects of aeolian processes.

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