Impact of Beach Surface Type on the Rate of Sand Transport by Wind

Rotnicka, J., 2011. Impact of beach surface type on the rate of sand transport by wind. Journal of Coastal Research, SI 64 (Proceedings of the 11th International Coastal Symposium), 2058 - 2062. Szczecin, Poland, ISSN 0749-0208. This study aimed at quantitative assessment of the impact of the bed surface type on the rate of aeolian transport on typical beaches of the temperate zone. The experiments were performed on a beach of the Leba Barrier, south Baltic coast, Poland, in 2006-2009. The beach was composed of medium-grained quartz sand. Depending on moisture content and the type of roughness elements, four types of sand surfaces were preselected: dry rippled, moist (moisture content up to 5%), wet (moisture content up to 9.25%) and covered with pebbles (cover in a range of 15% to 60%). Wind speed and direction were measured at 1 m height. Sand transport rate was measured using a 0.5 in high vertical sand trap. The experiments were performed so as to represent conditions of saturated flux. Relationships between maximum sand transport rate and wind velocity on selected beach surfaces were established by regression analysis. All showed strong positive correlations. Results show that the sand transport rate is highest over moist and wet surfaces; in both cases, its dimensions are comparable, but vertical distributions of sand in a near-bed layer are different. Over the dry rippled and lag surfaces, the transport rate is lower. However, this difference decreases with increasing wind speed. For the lag surface, the relationship reverses at 9 m/s. The study also shows that moisture content up to 9.25% does not suppress the aeolian transport.