Hydrogeochemical assessment of groundwater in Isfahan province, Iran

Groundwater quality in five catchment areas in Isfahan province of Iran is assessed by measuring physicochemical parameters including major cation and anion compositions, pH, total dissolved solid, electrical conductivity and total hardness. For this purpose, 567 piezometric well samples were collected in October 2007. The abundance of major ions in four of the catchment areas including Gavkhuni, Ardestan, Salt lake and Central Iran desert basins is similar and follows Cl⁻ > SO₄ ²⁻ > Na⁺ > HCO₃ ⁻ > Ca²⁺ > Mg²⁺ > K⁺ > CO₃ ²⁻ trend, while in the fifth basin (Karoon), the trend changes into HCO₃ ⁻ > Ca²⁺ > Cl⁻ > SO₄ ²⁻ > Mg²⁺ > Na⁺ > K⁺ >CO₃ ²⁻. In general, four water facies are determined and it is shown that alkali elements and strong acids are dominating over alkaline earth and weak acids. Statistical analysis including Mann–Whitney U test indicate that physicochemical parameters in three of the five investigated basins [Gavkhuni, Ardestan and Central Iran desert (CID)] are similar, while Karoon and salt lake basins display different characteristics. The result indicate that groundwater west of the province is suitable for irrigation, while in the central and eastern parts of the province the groundwater loses its quality for this purpose. It is concluded that mineral dissolution and evapotranspiration are the main processes that determine major ion compositions.