Assessing the effect of landuse and lithology on spring water quality in Piranshahr watershed

The springs of Piranshahr watershed are sources that supplies drinking and irrigation water. Therefore، in this study geology and agricultural conditions is examined as the most important factor controlling spring water quality. After recording the geographical location of 145 springs، sampling was done in September 2012. The electrical conductivity (EC) were measured in the study area، whereas The values of other parameters، such as sodium ions، calcium ions، magnesium ions، potassium ions، carbonate ions، bicarbonate ions، chloride ions and sulfate ions were measured in the laboratory. Water quality parameters was analyzed، in which، the Piper diagram show the six types of water، including Ca-HCO3، Mg-HCO3، Ca-SO4، Mg-SO4، Na-HCO3 and Na-SO4. To investigate the influence of lithology (seven types of lithology) and landuse (two types of landuse) on spring’s water quality، the statistical analysis of variance (ANOVA) and t test was used، respectively. The results of statistical analysis showed that the parameters of springs، including EC، TDS، CO32-، HCO3-، Cl-، Ca2+، Mg2+ and TH in different formations of the study area have significant differences. Finally، averages of the water quality parameters of the lithology using Duncan test were compared. Also، landuse have a significant effect on parameters including CO32-، Cl- and K+. Gibbs diagram based on the results of chemical analysis showed that the chemical structure of water quality influenced by lithology. So the first and second priorities of influence on the water quality are lithology and landuse، respectively.