Articles | Volume 7, issue 1/2
Nonlin. Processes Geophys., 7, 31–35, 2000
https://doi.org/10.5194/npg-7-31-2000
Nonlin. Processes Geophys., 7, 31–35, 2000
https://doi.org/10.5194/npg-7-31-2000

  30 Jun 2000

30 Jun 2000

Permanent bedforms in a theoretical model of wave-sea-bed interactions

J. M. Becker and D. Bercovici J. M. Becker and D. Bercovici
  • Department of Geology and Geophysics, University of Hawaii at Manoa, Honolulu, HI, 96822, USA

Abstract. The interaction between sea waves and a deformable sea-bed is studied with a simple two-layer model in which the upper-layer fluid is inviscid and the lower-layer fluid is bi-viscous to account for non-Newtonian behaviour of sand and sediments. The nonlinear response of the system to periodic forcing by an external surface pressure is determined. It is shown that a simple bi-viscous rheology allows small wavelength morphology in the lower layer to be generated from large wavelength surface waves in the upper inviscid layer, although the morphology is not permanent. For a bi-viscous rheology with a pressure-dependent yield stress (which accounts for the fact that sand yields less readily under loading than unloading), however, small wavelength and permanent features are formed in the seabed.