APPLICATION DES MÉTHODES STATISTIQUES À L’ÉTUDE HYDROCHIMIQUE DES EAUX D’UN HYDROSYSTÈME TROPICAL : CAS DU BASSIN VERSANT DE LA RIVIÈRE ZIO (TOGO)

Abstract

Zio River is the only perennial river of Lake Togo basin. It passes through many urban areas including capital Lomé which it receives discharges of all kinds and subjected to several human pressures. This study aims to characterize the physicochemical quality of water from the source to the river mouth, identify pollution sources and highlight the impact of human activities on these waters quality. For this purpose water samples were taken during four times at each site and Physicochemical analyzes were done in the laboratory according to AFNOR methods. The results of these analyzes were accompanied by statistical analysis. Principal Component Analysis identified parameters influenced by human activities or effluents and those related to mineralization process. Factor scores of sampling sites on the bidimensional plane (F1XF2) showed increasing pollution or disturbance gradient of sites from upstream to downstream. Physicochemical quality study reveals that sites located at upstream are good quality, record the highest levels of dissolved oxygen (6 to 14.6 mgO2 / L) and are suitable for any purpose contrary to downstream sites waters, degraded by human activities and record lower levels of dissolved oxygen (0.6mgO2/L). Piper diagram showed dominance of Ca-HCO3 water type with the presence of Na-HCO3 water type and a few Na-Cl water type.