Figure 4: Formation of steady-state raked linear dunes from a local sand source.
From: Unravelling raked linear dunes to explain the coexistence of bedforms in complex dunefields
(a–d) Elongating raked linear dune and development of secondary bedforms. (e) A snapshot of the steady-state raked linear dune. Insets show the sand flux roses and the predicted orientations of dunes growing by extension (fingering mode, black arrow) and perpendicularly to the maximum gross bedform-normal transport (bed instability mode, red arrows). The green arrow shows the resultant sand flux at the crest of dune growing in the bed instability mode. By definition, this is also the migration direction of these dunes. The asymmetric dune pattern results from the obliquity between the two dune orientations and the oblique propagation of secondary bedforms.
