Impact of Beach Surface Moisture on Aeolian Sand Transport Rate and Vertical Mass Flux Distribution, the Case of Atlantic Coast, Southern Morocco

Several factors impact the aeolian sand transport rate, among which surface moisture is predominant. The current research aims to compare the simultaneous measurements of sand transport on moist and dry surfaces. The research is conducted at the Atlantic coast, 50 km south of Tarfaya, Morocco. Sand transport rate and vertical mass flux distribution are measured on three sandy surface types: (i) moist flat beach surface, (ii) dry rippled sand patch, and (iii) dry rippled sand at the dune crest. The findings show that at the same wind conditions, the total sand transport rate is greater on a dry surface than on a moist one only at lower wind velocity (up to 8–10 m/s). At higher wind speed, it is more significant on a moist surface. This can be related to the formation of a greater thickness of the saltation layer resulted from the harder rebound surface of moist sand.