Sediment flux, wind erosion and net erosion influenced by soil bed length, wind velocity and aggregate size distribution

Knowledge of wind erosion as a dynamic phenomenon changing in space is of importance in measuring and modeling soil erosion. While, many erosion studies have been done on the effect of bed length on wind erosion rate, little attention has been paid to the spatial changes of net erosion rate in different soil bed lengths. The aim of this study is to examine the effect of soil bed length, surface aggregate size distribution and wind velocity on sediment flux and wind/net erosion rates. For this purpose, three soil samples were placed in seven bed lengths ranging from 1 to 7 m and subjected to different wind velocities of 6, 10 and 14 m s−1 using a wind tunnel. The result showed that total sediment flux increased at longer soil bed lengths, whereas the reverse trend was found for wind erosion and net erosion rates, which was attributed to the gradual saturation of air flow with eroded particles and the formation of armor layer. Depends on soil bed length, the measured wind erosion rate varied from 154.8 to 3783.7 g m−2 min−1. Toward the end sections of the bed length, the reduction in net erosion (34.1% to 79.1%) was higher than the reduction in wind erosion rate (18.9% to 50.0%), implying that for every length section, the measured wind erosion rates were higher than the obtained net erosion rates. Soil bed length was found to be an appropriate single variable to predict wind/net erosion rates using a power function. Furthermore, wind erosion rate (Q) was modeled as a function of bed length (L), the mean weight diameter of aggregates (MWD) and wind velocity (V), that was Q = 6 × L−0.225 × MWD−0.579 × V1.975, R2 = 0.945⁎⁎. It was also found that the soil containing coarser aggregates exhibited less sediment flux and wind/net erosion rates. The findings of this research revealed that the measurement of wind erosion on different bed lengths under laboratory conditions will result in effective discrepancies in the erosion rates, worldwide; however environmental conditions can be different in areal case. Therefore, it is necessary to pay special attention to the scale effect of soil bed length in future soil erosion studies.