Soil wind erosion rate on rough surfaces: A dynamical model derived from an invariant pattern of the shear-stress probability density function of the soil surface

Abstract

Landscape types with sparse vegetation, gravel cover and ridge-like tillage measures are widely distributed in dryland, and they are the main areas of soil loss and dust emissions caused by soil wind erosion. The widespread land degradation caused by soil wind erosion in these areas is the main reason for the low quality of life of the local people. Therefore, soil wind erosion control has become an urgent task for governments. As is well known, understanding the dynamic process of soil wind erosion is the premise on which effective measures of soil wind erosion control are developed. However, the spatial heterogeneity of shear-stress generated by wind on the soil of rough surfaces and its driving mechanism on soil wind erosion have not been fully understood. Based on a series of wind tunnel experiments, the distribution of wind-caused shear-stress on the exposed soil surface (τs) of rough surfaces with plants, gravels, and ridges was calculated, and the probability density function of τs on these rough surfaces followed the pattern of the logistic function. The location parameter and scale parameter in the logistic function were correlated with the lateral coverage, ridge index and friction wind velocity on rough surfaces. Subsequently, a soil wind erosion rate model with the characteristics of an upscaling point-scale process was established. Tested by multi-source experimental data, the model has a satisfactory prediction ability. These findings greatly improved the understanding of the spatial heterogeneity of τs and the driving mechanism of τs in soil wind erosion, which will help establish a dynamic-based wind erosion rate model in the future.