barchan (adj. barchanoid) Crescent-shaped mobile dune in a sand desert in which the wind blows predominantly from one direction. The dune moves by the erosion of sand from the windward slope, and its accumulation on the steeper lee or slip slope which stands at about 32°. Average velocities of dune movement are 10–20 m/yr.

barchan(adj.barchanoid) A crescent-shaped mobile dune in a sand desert in which the wind blows predominantly from one direction. The dune moves by the erosion of sand from the windward slope and its accumulation on the steeper lee or slip slope, which stands at about 32°. Average velocities of dune movement are 10–20 m/yr.