The flowing of sand. Dong et al. (2004) Geomorph. 57, 1–2 find that sand flux over a sandy surface increases with height in the very near surface layer, but then decays exponentially; see also Wang et al. (2008) Geomorph. 96, 1–2. Yang et al. (2011) J. Arid Land 3, 3, 199 estimate a sand flux in the Taklimakan Desert, China, to be 258.67 x 10^–4 kg/m^.s.