Study on the dynamics of sand dunes in Tunisia : mobile barkhans move in the direction of the Sahara

The speed and direction of displacement of individual eyebrow-shaped dunes (barkhans) was monitored at two experimental stations (Menzel El Habib and Noueil) in southern Tunisia. The displacement of the barkhans was followed from I June 1992 until 31 May 1993. After I year the barkhan at Noueil had moved 51 m in the south west direction and the barkhan at Menzel EE Habib had moved 485 m further westward (west by southwest). The dominant active winds with windspeeds higher than 3 m s(-1) sms1 were coming from east, southeast, and north. Hence the barkhans migrated in the direction of the Sahara and in particular to the Erg Oriental. The desertification process along the border of the Sahara was not due to sand movement coming from the Sahara, but resulted from a disequilibrium of the ecological system