Evaluation of Zohreh River Water Quality, Impacted by Natural and Anthropogenic Pollution Sources, Using Multivariate Statistical Techniques

Discriminant analysis (DA) and principal component analysis (PCA) as a multivariate statistical technique, were applied for the evaluation of temporal and spatial variation and the interpretation of a large complex water quality data set of the Zohre river basin, monitoring 16 water quality parameters collected over 16 - 45 years (1966 - 2013), in four stations sites (1554 observations for each parameter). Principal component analysis, applied to the data sets of the four studied stations resulted in four, four, four and three latent factors explaining 78.985, 83.828, 77.648, and 77.68 % of the total variance in water quality data sets of Kheirabad, Poleflour, Chambostan and Dehmolla stations, respectively. The factors obtained from PCA analysis indicate that the parameters responsible for water quality variations are mainly related to TDS, EC, Cl, Na, SAR and %Na (natural sources included Gypsum and salt crystal are frequently grown in supratidal, intertidal zones of Zohreh delta and Chamshir faults I and II fault zone, and anthropogenic source caused by sugarcane culture withdrawals, discharging of domestic and industrial wastewaters) in all studied stations. DA provided an important data reduction as it uses only seven parameters (discharge, temperature, electrical conductivity, HCO3- , Cl, %Na and T-Hardness), affording more than 58.5% correct assignations in temporal analysis.