Amirreza Sharifan - Department of Civil Engineering, Ferdowsi University of Mashhad, Mashhad, Iran,
Hossien Sharifan - Associate Professor, Gorgan University of Agricultural Sciences and Natural Resources, Department of Water Engineering, Gorgan, Iran
Shahla Safari - Graduated of the Department of Water Engineering, Gorgan University of Agricultural Sciences and Natural Resources

This research investigates the temporal variations of groundwater quality parameters in the Gorgan-Qareh Su basin, located in the Golestan province, including salinity (EC), acidity (pH), anions, cations, sodium absorption ratio (SAR), and total dissolved solids (TDS) from ۲۰۰۱to ۲۰۱۰. The spatial variations of groundwater quality parameters in ۲۰۰۹ were also examined using the geostatistical Kriging method. Furthermore, station categorization was performed using statistical analysis in the SAS software. Finally, the water quality status of the stations in ۲۰۰۹ and their long-term averages were determined to allocate water resources appropriately for agricultural, drinking, and industrial purposes in the Gorgan-Qareh Su basin. Furthermore, according to the results obtained from the water quality analysis, in the first half of ۲۰۰۹, slightly more than half of the stations were slightly saline. In the second half of ۲۰۰۹, in terms of water quality for industrial purposes, ۶۶% of the stations had usable water.

Water quality, Geostatistics, Cluster analysis, Time series, Schuler diagram, Wilcox diagram.