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Influence of bed roughness on dune and megaripple generation
Author(s) -
Idier Déborah,
Astruc Dominique,
Hulscher Suzanne J. M. H.
Publication year - 2004
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2004gl019969
Subject(s) - seabed , geology , surface finish , instability , geomorphology , geotechnical engineering , grain size , bedform , mode (computer interface) , hydraulic roughness , geometry , mechanics , sediment transport , sediment , materials science , physics , oceanography , mathematics , composite material , computer science , operating system
Richards [1980] conjectured that megaripples of the continental shelf are due to a seabed instability in the presence of seabed ripples. Towards a better understanding of this megaripple formation process, we use a morphodynamical numerical model to investigate the bed roughness influence on the bed load–induced linear stability of a sandy bed. We find that the linearly most amplified mode shifts from a dune mode (grain roughness) towards a megaripple mode (large bed roughness). Then, we discuss how megaripples could be generated over a flat bed and over dunes.