Trend Analysis of Water Chemical Quality of East Azerbaijan Rivers

The aim of this study is trend analysis of streamflows of east Azerbaijan using the non-parametric methods. For this purpose the information of consentration of water quality ions (Ca, Mg, Cl, Na, HCo3, pH, So4, TDS, EC, SAR, Total Cations, Total Anions and Na%) of ten hydrometric stations (1983-2008) were used. To test trends the Mann-Kendal scheme after removing all significant autocorrelation effects from the data were used. To estimate trend line slope the non-parametric Sen´s estimator method was used. Results showed that trends of positive ions and EC were upward for most of the stations. Those stations which had negative trend in streamflow also exhibited positive trend in concentration of chemical elements of surface water. Furthermore, investigation of streamflow water quality using the Wilcox on method showed that the quality of water declined comparing the last decades. The reason of such declination attributed to the decreasing trend of streamflow and conveying pollutant materials into the rivers.