Logistic growth models for describing the fetch effect of aeolian sand transport

Abstract Soil loss and dust emissions due to wind erosion result in soil degradation. The fetch effect, referring to an increase in aeolian sand transport with downstream distance over an eroding surface, is important in modeling wind erosion and parameterizing sand dunes and ripples. Several fetch models have been developed to quantitatively depict the variation of sand flux over a sand bed. The present study first verifies that the family of logistic growth models extensively used in biological systems can be used to describe the fetch process of sand flux. The performances of Fryrear (Fryrear and Selah, 1996), Visser (Visser et al., 2004), Stout (Stout, 1990), Andreotti (Andreotti et al., 2010), and logistic fetch models are investigated using data for 39 wind tunnel experiments across six countries and 51 field measurements across four countries. Results reveal that the patterns of sand flux across a sand bed generally govern the goodness of fit of these fetch models. The logistic models best describe the observed sand flux data and well simulate the maximum sand flux ( fmax ) and corresponding flux saturation length ( L sat ). Generally, the Fryrear, Visser, and logistic models yielded similar fmax and L sat while the Stout, and Andreotti models overestimate fmax and L sat . More studies are required to explore what factors affect these fitting coefficients (such as fmax and L sat ) and how for the logistic models.