Assessment of the Trophic State and Hydrochemical Characterization of Zerdaza Reservoir (North-East of Algeria)

From January to December 2013, a monthly investigation was carried out in order to assess the water quality of the Zerdaza reservoir located in the North-East of Algeria. The evaluation of the trophic status was made according to the Carlson’s Trophic State Index (CTSI). The hydrochemical facies was determined by using the Piper diagram and by the comparison of some water parameters values with the Algerian Environmental Quality Standards for Surface Waters. The results of the CTSI showed a very slight variation indicating that this reservoir water is eutrophic. The water is characterized by the predominance of Chlorinated-Sulphated Sodium–Calcium facies. Statistical analysis of the Standard Deviation (StD) indicated two categories of parameters. The first category was characterized by a very low variation and concerned the values of the Secchi depth (Sd), water Temperature (Temp), pH, Cl-, Total Nitrogen (TN), Mg+2, NO3-, K+ and Ca+2. The second one was characterized by a moderate to a high variation including the values of Chlorophyll a (Chl a), SO4-2, HCO3-, Total Phosphorus (TP) and Na+. The mean comparison of these parameters with the Algerian Standard Values for raw waters intended for human consumption showed that the waters of the Zerdaza reservoir were consistent with these standards for the period of investigation.