Quantification des matières en suspension et valorisation des sédiments de dragage à l’échelle d’un bassin semi-aride: Cas du barrage du K’sob (Algérie)

Abstract

Due to the semi-arid climate, scarcity of vegetation, the presence of a sometimes steep slope, Algeria is vulnerable to soil erosion that threatens its socio-economic development. In the watershed of K’sob, transport of suspended sediment by rivers is a disturbing phenomenon due to siltation to 80 % of the dam at the outlet. Data of suspended sediment concentrations are closely related to liquid discharge (Q). Models of solid discharge (Qs) according to the equation Qs = aQb were used to perform qualitative and quantitative analysis of suspended sediment. Different scales of analysis helped identify and explain conclusively seasonal models. Sediment production is very high in the fall. In the spring, despite the increase in discharge, it is less significant. In summer, during a period of disappearance of vegetation cover, highly loaded floods are sometimes observed. Currently, millions of cubic meters of sediments are dredged each year. This large volume is an economic, environmental and ecological problem. To remedy this, an experimental study of manufacturing brick has been proposed with 65 % of sediment, 25 % of dune sand used as an additive and 10 % water. The shrinkage is minimal for a solid brick fabricated to 800 °C during 6 h of cooking. The mechanical tests carried out on the brick exhibit acceptable values of compression strength, mass density and water absorption. The study of the evolution of these parameters for different pressing intensities (13.2–20–30 and 40 kN) at different ages (4, 14, 21, and 28 days) shows that the solid brick acquires its resistance only after 21 days.