evaluate the stability of surface water quality variation in gorganrood river basin

information on water quality and pollution sources is important for the implementation of sustainable water resource management strategies. in this research, to evaluate spatial variation and the interpretation of large complex water quality data taken at seven different sites along the gorganrood river were subjected to multivariate statistical analysis. the factor analysis generated two significant factors, which explained 97.80% of the variance in data sets. factor 1 and factor 2 explained 86.27 and 15.76% of the total variance in water quality data sets. principle components analysis results revealed that surface water quality was mainly controlled by ca and ph parameters. in next step, information entropy theory applied to interpret the stability of surface water quality variation in each factors and each parameters. overall results revealed instability in data recorded in tamar and galikesh sites and in factor 2, ec and tds, lazoreh has highest instability. with a well knowing the factor score and overlaying entropy, infactor1, mg and cl had highest stability. the ranks of information entropy values for mg parameter at galikesh, tagi abad, basir abad, ramian and tangrah sites vary noticeably due to geological formation. in general, sampling uncertainties are highly site specific.