The impact of a multiple‐row Tamarix windbreak on grain size parameters of aeolian sand flux

Abstract

AbstractUnderstanding the effects of windbreaks on aeolian sediment transport rates, and the size distribution of aeolian sediments transported through them, is important for designing windbreaks to optimize their wind erosion mitigation benefits. This field study determines the size distribution of aeolian sediments upwind (x = −100 m), within (x = 100 and 256 m) and downwind (x = 448 and 560 m) (where x is the distance from the first row of windbreak) of a multi‐row Tamarix windbreak as the basis for further investigation of the influence of vegetation on aeolian sediment characteristics. The volumetric percentage of grains around the peaks of 100 and 20–30 µm showed variability with distance and between the three measured events. We found that the vertical distribution of grain size parameters indicated that mean grain size (Mz) may decrease with height upwind of the windbreak, and inflections were observed in the profiles of sorting (σ1), skewness (SK), and kurtosis (KG) within the windbreak, which may be attributable to blocking and trapping effect of the vegetation. Sediments were poorly sorted with the distributions of grain sizes being fine‐skewed and leptokurtic. The horizontal distribution of grain size indicated that Mz increased from x = −100 m to x = 100 m and then decreased at x = 256 m, indicating that the windbreak was unable to retain small particles. The windbreak could trap particle sizes <50 µm and particles >50 µm transported to downwind region of windbreak. Within the windbreak, SK and KG increased, and σ1 decreased. Downwind of the windbreak (at x = 448 and 560 m), Mz and KG increased, and σ1 and SK decreased. The results of the current study provide preliminary information on the variability of aeolian sediment grain sizes during transport relative to vegetation and suggest that multirow windbreaks could influence downwind particulate matter size concentrations and soil health.