Abstract

Because of its semi-arid climate, the presence of abrupt relief with a weak vegetation cover, Maghreb is one of the most vulnerable regions of the world exposed to soils erosion. However, few studies have examined the mechanisms of this phenomenon in Maghreb. It is in this context that our contribution is registered. It is based on a detailed analysis of suspended sediments loads and liquid discharges measured at the outlet of the Upper Tafna basin (256 km²) in northwest Algeria. The study focuses on 1257 instantaneous values collected from September 1988 to August 1993. This period represents a part of a long cycle of dryness that dropped over the area since 1975. During this last, we noted a greater susceptibility to surface runoff. The increase in aridity is accompanied by an increase in the erosive potential. During this five studies year’s, the follow-up of the chronological evolution of the suspended sediment load according to the liquid flow shows that these two parameters exhibit various forms of hysteresis that are characterized as well by their forms by their values. The shapes analysis of the hysteresis offers the possibility of showing various mechanisms of erosion and transport generated by the principal hydro-climatic process that operates in the catchment area.

Keywords: Suspended sediment load, hysteresis, mechanisms of erosion, Sebdou Wadi, semi-arid area, Algeria