Influencing Factors of Repose Angle of Sand Dunes: an experiment

Repose angle is an important sand dune parameter, which determines the shape of sand dunes. On the base of observation data, this paper analyze the influencing factors of sand dunes' repose angles from view point of Blown Sand Physics. Experimental results show that molecular force among particles is determinant to the repose angle of fine sand dunes. The particle size does not directly influence the repose angle of sand dunes, but has an indirect impact through its sphericity and surface roughness, especially the sphericity acts as the main factor. Even at the same average particle size, the repose angle can be different under different grain compositions, and with the increasing of the uneven-class of grain compositions, the repose angle increases correspondingly. In addition, the sand texture also influences the repose angle of sand dunes. Even with same grain compositions, the repose angles of sand dunes may differ greatly duo to different sand texture. Compared with other factors, water content has relatively strong influence on the repose angles of sand dunes; with the increasing of water content, the repose angle increases firstly and then decreases.