Locally modified surface winds on linear dunes as derived from directional raingauges

• Published in: Earth surface processes and landforms Vol. 27; no. 8; pp. 867 - 889
• Main Authors: Sharon, David, Margalit, Adina, Berkowicz, Simon M.
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01-08-2002; Wiley
• Subjects: Arid and mediterranean areas; Bgi / Prodig; directional raingauges; Geomorphology; linear dunes; locally modified wind field; Negev desert; Physical geography; raindrop trajectories; reversed surface flow; Israel; Negev; Precipitation; Aeolian landform; Wind speed; Runoff; Arid area; Dune; Desert; Rainstorm
• ISSN: 0197-9337; 1096-9837
• DOI: 10.1002/esp.358

The study deals with local airflow patterns induced by 12–16 m high, partly vegetated dunes, under various prevailing wind conditions. Detailed empirical data were derived by means of an unconventional use of directional raingauges. The utility and accuracy of the method have been previously tested in a combined empirical and numerical study over ridges on a similar scale. Results are presented on the nature, extent and intensity of locally modified patterns of surface flow and on their dependence on wind conditions and slope inclination. Results may serve to verify or refine existing perceptions or models of the flow affecting sand movement over dunes. For example, deflected surface wind flow and even stationary vortices were found to form under winds with resultant angles of incidence of only 5–10° relative to the axes of the dunes, and on slopes inclined only 12–15°, i.e. lower angles than often assumed in previous studies of dune morphology. Various effects of the resulting surface flow on the dune ecosystem are also referred to, e.g. the distribution of settling dust and seed dispersal. Copyright © 2002 John Wiley & Sons, Ltd.