Assessment of the seasonal variations in hydrochemistry of Oued Fodda dam, Algeria

This study was carried out on the surface water of Oued Fodda dam in western Algeria, and aimed to evaluate the seasonal variations of chemical characteristics with the aim to define the processes controlling the mineralization of surface water in this dam. The results showed significant variations in the majority of parameters during the study period from 2009 to 2013, indicating slightly alkaline water, and a SO₄-Cl-Ca-Mg water type. Principal component analysis (PCA) and cluster analysis (CA) were used to explain the correlations between the parameters analysed, and the probable sources of surface water contamination. The calculation of saturation indices (SI) of water indicated undersaturated water with respect to halite (NaCl), and equilibrium with respect to the other minerals. While, the temporal variation of physico-chemical parameters such as EC, TDS, SO₄^2-, Cl^-, Ca²⁺, Mg²⁺ indicated a reverse adjustment between physico-chemical parameters and water volumes (WV) in this dam, which can be explained by the weathering of silicate and carbonate minerals, these were justified by the use of ionic ratios, diagrams and scatter plots and multivariate statistical techniques. Conversely, evaluation of the organic water pollution level in this dam showed a water quality from moderately to severely polluted.