Multivariate statistical method including cluster analysis (CA) was used to assess temporal and spatial variations in the water quality of Euphrates River, Iraq, for a period 2008-2009 using 16 parameters at 11 sampling sites. Hierarchical CA grouped the 8 months into three periods (I, II and III) and classified the 11 sampling sites into two groups (I and II) based on similarities of water quality characteristics. The temporal pattern shows that April has higher pollution level relative to the other months. Spatially, sampling site 7 (S7) has lower pollution level while the other sampling sites have higher pollution level. Thus, this study shows usefulness of cluster analysis method for analyzing and interpreting of surface water dataset to assess the temporal and spatial variations in the water quality parameters and the optimization of regional water quality sampling network.

The physico-chemical parameters of Euphrates River water were studied between Heet and Ramadi cities during November 2008 to June 2009. Water were samples collected from eleven stations and analyzed for Temperature, Turbidity, Electrical conductivity (EC), Total suspended solids (TSS), pH, Total dissolved salts (TDS), Dissolved oxygen (DO), Biochemical oxygen demand (BOD), Calcium, Potassium, Sodium, Sulphate, Phosphate, Bicarbonates, Chloride, Nitrate and Total hardness. The observed values of these physico-chemical parameters were compared with WHO standards. Some parameters (Turbidity, TSS, TDS, BOD, Calcium, Sodium and Total hardness) exceeded the permissible limits of WHO standards, while other parameters were within the permissible limits. Statistical studies have been carried out by calculating correlation coefficients between different pairs of parameters. Monthly and spatial variations of physico-chemical parameters were investigated