Analysis of physiochemical and microbial quality of waters of the Karkheh River in southwestern Iran using multivariate statistical methods

Rapid population growth as well as agricultural and industrial development have increased the contamination of Iranian rivers. This study utilized principal components analysis (PCA) to determine the degree of significance of qualitative parameters of water resources in the Karkheh River in southwestern Iran. Cluster analysis (CA) grouped the monitoring stations based on the water quality data under measurement. The first three components obtained from the PCA accounted for 39.68, 35.04, and 17.76% of the total variance, respectively; these three components explained a total of 92.49% of the variance of the data sets. The PCA factors indicated that the parameters influencing changes in water quality were generally related to weathering and land washing in response to floods, organic contamination from household wastewater, waste from sand washing, and runoff from chemical fertilizers. Moreover, the PCA results indicated that the relative quality of the river water in the downstream areas, when compared with upstream areas, was worse due to the greater concentration of contamination sources in the vicinity of the monitoring stations. Given Iran’s water crisis, the preservation and reclamation of this valuable resource require greater attention from the relevant authorities