Aeolian dust accumulation by rock fragment substrata: influence of number and textural composition of pebble layers on dust accumulation

Rock fragments are a common occurrence in many arid and semiarid areas and can act as an effective dust trap. In the previous studies, dust accumulation on rock fragment substrata was investigated in a single stone layer, with stones of an identical size. The objective of the present study was to explore the effect of the number and the textural composition of pebble layers on aeolian dust accumulation in the semiarid loess area of NW China. The results of the experiment indicate that pebble layers have obvious effect upon dust accumulation. The effect was very pronounced for two layers of pebbles as compared to one layer. Dust accumulation on pebbles increased with increasing number of pebble layers. Total dust accumulation and accumulation between and underneath the pebbles in a single layer was significantly less than in two and three layers, however, no significant difference in dust accumulation was found between two and three layers. This suggests that a double layer of pebbles may be a better aeolian trap than single, triple or multi-layered pebble surfaces. The textural composition of a pebble surface has only minor effects on dust accumulation. Dust quantity on the pebbles was almost identical for all the combinations tested. Total dust accumulation and accumulation between and underneath the pebbles tended to increase with increasing proportion of small-size pebbles. The results of the study might be of use for proper management of gravel-mulched fields and stone barriers used for wind erosion control in the arid regions.