A method for establishing the critical threshold for aeolian transport in the field

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 may 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 region of low-relief dunes 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 values could be calculated every 5 minutes. This new method allows for routine monitoring of surface threshold conditions in the field. Example threshold calculations are presented and they demonstrate that the method works well. Published in 2004 by John Wiley Sons, Ltd.