THE MORPHODYNAMICS OF MOBILE DUNES IN THE R’HIR VALLEY (ALGERIA)

Abstract

The migration of mobile dunes poses a persistent threat to oases and infrastructure located in the R’hir Valley. This phenomenon, intensified by springtime sandstorms—particularly easterly Chergui winds—also affects herbaceous vegetation cover to the east of the valley, which is already severely degraded.

This region is particularly vulnerable due to a complex sediment budget and the convergence of two major aeolian regimes (easterly and northwesterly winds), which together produce intricate sand dynamics. The conducted study reveals that mobile dunes in this valley exhibit an average mobility of 28.9 m/year toward the southwest (244°), with a peak movement of 12.6 m over a three-month period in spring, representing 44% of the annual displacement.

The impact of this dune dynamic is manifested in increased sand encroachment onto agricultural areas and infrastructure, resulting in high sand removal costs and threatening the ecological and socio-economic balance of the region.