Elongation and Stability of a Linear Dune

Olivier Rozier (1) , Clement Narteau (1) , Cyril Gadal (2) , Philippe Claudin (3) , Sylvain Courrech Du Pont (4)

1 IPGP - Institut de Physique du Globe de Paris
2 IPGP - Institut de Physique du Globe de Paris
3 PMMH - Physique et mécanique des milieux hétérogenes (UMR 7636)
4 MSC - Matière et Systèmes Complexes

Compared to barchan dunes, the morphodynamics of linear dunes that elongate on a nonerodible bed have barely been investigated by means of laboratory experiments or numerical simulations. Using a cellular automaton model, we study the elongation of a solitary linear dune from a sand source and show that it can reach a steady state. This steady state is analyzed to understand the physical processes at work along the dune. Crest reversals together with avalanche processes control the shape of transverse sections. Dune width and height decrease almost linearly with distance downstream until the minimum size for dune is reached. This is associated with a constant sand loss along the dune, which eventually compensates for the sediment influx and sets the dune length. This sand budget is discussed to distinguish an elongating linear dune from a barchan dune and to explain the complexity of linear dune fields in nature.

Keywords: solitary linear dune; steady-state morphology; sand flux estimation; finger dune; elongating dune

Domains: Sciences of the Universe [physics]; Earth Sciences

Olivier Rozier, Clement Narteau, Cyril Gadal, Philippe Claudin, Sylvain Courrech Du Pont. Elongation and Stability of a Linear Dune. Geophysical Research Letters, 2019, 46 (24), pp.14521-14530. ⟨10.1029/2019GL085147⟩. ⟨insu-02925029⟩