Aeolian Morphogenesis And Strategy Of Fight Against Desertification In Algeria (Hodna And Zibans Basin)

The evolution of the relief in the arid areas is under the influence of the wind whose varied actions are expressed by the corrosion exerted by the sand winds, by dune constructions, which can take imposing extensions in the form of ergs.

The action of the wind causes to the engineers problems of fixing of sands because the vegetable cover is here, unimportant to ensure a good stability of the dunes.

The knowledge of the methods of the accumulation of sands requires systematic statements on the ground, which are often lacking in Algeria and in the arid areas of the world.

The fight against mobile sands and the projection of the dunes supposes the precise knowledge of the methods of transport of sands according to the configuration of the ground, of the granulometry of sands, the speed but also direction of the dominant winds.

• Forcing the deposit of sands on the upstream wind of the area to be protected

• Increasing the potential of transport of sands by the wind through the zone to protect in order to facilitate a good transit of sands

• Reducing supply of sands to its simple form

• Deflecting mobile sands beyond the surfaces to be protected

These various approaches made it possible to develop and apply the stability techniques of the mobile dunes.

In the light of all these methods, we present some elements of a strategy of fixing the mobile dunes in Algeria, starting from the Hodna basin and Zibans range located at the Eastern ending of the Saharian Atlas.

In the Hodna basin and the area of Zibans we identified fields of sharp dunes whose current progression threatens stranding cities like Bou Saada, the town of Biskra and the oases in Zibans. The preliminary treatment of these mobile dunes showed a failure because of specific interventions, very localized; the fixing of the mobile dunes must pass through the study of wind dynamics within its global framework in order to be able to determine the extension of the sphere of activity of the wind; zones of supply sands, aeolian corridors or of transit of sands and accumulation areas.

On the basis of control and identification of these zones of actions of the wind, one can advance suggestions for a solution to the effective treatment of the mobile dunes and their fixing in these areas in the framework of the strategy of the fight against desertification in Algeria.