Etude de la Minéralisation et de la Granulométrie des Sols de la Sebkha de Ouargla

Abstract

The Sebkha of Ouargla is located north-west of the city of Ouargla in the lower Eastern Sahara. The climate of the region is known for its particularly marked by low and erratic rainfall aridity, in one hand, and the thermal amplitudes and temperatures too high on the other. This aridity is not observed only on the lack of rainfall, but also by high evaporation which is one of the current major climatic factors prevailing in the region. The latter exceeds 380 mm in July. To understand the evolution of salinity in this system, physico-chemical study of various constituent training is conducted along a north-south profile. Six piezometers were installed for sampling of surface water and groundwater monitoring groundwater level. Particle size analysis is used to determine the relative amount of different elements constituting the ground (gravels, sands, silts, clays). The size distribution curves showed that most of the samples belong to the class of arenites. This is mostly fine sand (84%) and medium sand (10%). The physico-chemical analysis of the soil 1/5 affirms the high salinity of samples. The values of electrical conductivity at 25 ° C are between 3.15 and 24.26 dS.m-1. The insoluble rate exceeds 80%, the gypsum is more than 12% while the limestone is negligible (<2%).