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Submitted to: Earth Surface Processes and Landforms
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 1/29/2004 Publication Date: 9/1/2004 Citation: Stout, J.E. 2004. A method for establishing the critical threshold for aeolian transport. Earth Surface Processes and Landforms. 29(10):1195-1207. Interpretive Summary: As sandy soils are eroded by wind, dust is generated by the action of larger sand grains bouncing across the surface releasing clouds of finer dust particles. Once detached from the surface fine dust particles are blown vast distances downwind resulting in significant topsoil loss and impacting air quality. Ideally one would like to be able to predict periods of dust generation from a measured wind velocity record. To do so requires knowledge of the critical threshold for soil movement. Here we report results from a field experiment in which measurements of blowing sand and wind speed were used to calculate threshold wind speed under natural field conditions using a newly developed mathematical expression. Results from a field study conducted in West Texas reveal that threshold can be established with enough precision to identify temporal patterns resulting from changing surface conditions. Technical Abstract: A basic feature of any wind-eroding surface is its threshold - the wind speed at which sediment transport is initiated. A new method was developed and tested that allows for the rapid determination of threshold under natural wind conditions in the field. A mathematical expression that relates saltation activity and relative wind strength was reformulated so that threshold can be calculated from measurements of saltation activity and the mean and standard deviation of wind speed. To test the new method and determine its usefulness, a field experiment was performed within a sandy section on the Southern High Plains of West Texas. The experimental system consisted of a 2-m meteorological tower and a piezoelectric saltation sensor. It was found that during periods of active aeolian activity, threshold vlaues could be calculated every five minutes. This new method allows for routine monitoring of surface threshold conditions in the field. Example threshold calculations are presented. |
