Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

Profiles Analysis of Sand Dunes and Their Steady State Signification

Haim Tsoar
Geografiska Annaler. Series A, Physical Geography
Vol. 67, No. 1/2 (1985), pp. 47-59
Published by: Wiley on behalf of the Swedish Society for Anthropology and Geography
DOI: 10.2307/520465
Stable URL: http://www.jstor.org/stable/520465
Page Count: 13
  • Subscribe ($19.50)
  • Cite this Item
Profiles Analysis of Sand Dunes and Their Steady State Signification
Preview not available

Abstract

Sand dunes that are subjected to different wind directions attain different steady state profiles. Two fundamental types of profile are known: the convex asymmetric one, characterizing barchans and transverse dunes, and the symmetric triangular one of seif dune. The distribution of wind velocity along these two fundamental profiles indicates that the convex profile of barchan and transverse dunes are in a steady state to uni-directional winds. A steady state profile having a separate crest and brink ensues a higher advance of slip-face relative to the windward slope. A triangular sharp-edged profile of seif dunes is not in a steady state under long-term perpendicular uni-directional wind. Steady state can be attained, however, by bi-directional winds of oblique approach to the dune. In this case seif dunes are in a steady state with respect to profile oblique to dune axis and parallel to wind direction. A sharp-edged profile causes a substantial separation of perpendicular flow over the lee slope. The separation vortex reduces the wind-velocity's rate of increase near the crest line which keep its sharp profile during a short period of perpendicular wind. In the case of the wind shifting to a perpendicular direction for a longer period, the triangular shape will turn into a convex asymmetric one.

Page Thumbnails

  • Thumbnail: Page 
47
    47
  • Thumbnail: Page 
48
    48
  • Thumbnail: Page 
49
    49
  • Thumbnail: Page 
50
    50
  • Thumbnail: Page 
51
    51
  • Thumbnail: Page 
52
    52
  • Thumbnail: Page 
53
    53
  • Thumbnail: Page 
54
    54
  • Thumbnail: Page 
55
    55
  • Thumbnail: Page 
56
    56
  • Thumbnail: Page 
57
    57
  • Thumbnail: Page 
58
    58
  • Thumbnail: Page 
59
    59