Effets Des Activités Humaines Sur Les Ressources En Eaux Dans Les Régions Semi-arides Et Arides D’algérie

Résumé: Aquatic ecosystems in arid and semi-arid regions are characterized by high biological diversity and provide important ecological and socio-economic functions. However, they are affected and threatened by human activities. This work is a contribution to the study of the contamination of the surface water of the main wadis of the El Hodna watershed which flow into the wetland of Chott El Hodna, M’sila, and the wetland of Bazer Sakhra, Sétif. Based on the physicochemical parameters that are usually measured during conventional experimental monitoring: Conductivity, temperature, hydrogen potential, dissolved oxygen, dry residues , total dissolved solids, chemical oxygen demand COD, biological oxygen demand at 5 days BOD5, nitrate (NO-3), nitrite (NO-2), ammonium (NH4+), Phosphate (PO+4) and SO₄-² sulfates, The results of the physico-chemical analyzes showed that the waters of the two study areas are highly mineralized. The water quality was evaluated by two quality indices (WQI) according to uses for irrigation and aquatic life. Whereas, the organic load was measured through the calculation of the water index organic pollution (IPO) of Leclercq. The results obtained showed that the different types of pollution (industrial, domestic and agricultural) affect the surface water of the study areas, which led to the degradation of these aquatic ecosystems and consequently its biodiversity and public health. The different correlations between the elements and the principal component analysis (PCA) displayed that the alteration of the physico-chemical quality of the surface water of the wadis of the Hodna Basin and the Bazer-Sakhra wetland is the result of two main factors which are: the natural factor (geology) and human factor (urban, industrial and agricultural pollution

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