Multidisciplinary approach to evaluate groundwater salinity in Saveh Plain, Iran

Salinity is one of the most important groundwater quality problems in arid and semi-arid regions, such as Saveh Plain, Iran. Principal component analysis and factor analysis (PCA/FA) in collaboration with structural equation modelling (SEM) revealed that Na⁺, Cl⁻, EC, TDS, and salinity significantly influenced the groundwater quality in the study area. The spatial distribution map of factor score one represents high loading of salinity on the central, eastern, and south-eastern side of the plain. Groundwater quality evaluation using TDS versus total hardness suggested that around 90 % of the total samples are hard-brackish type, representing their unsuitability for drinking purposes. Ionic abundance is in the order of Na⁺ > Mg²⁺ > Ca²⁺ > K⁺ and Cl⁻ > SO₄ ²⁻ > HCO₃ ⁻, indicating that the groundwater facies varied from Na–Mg–Ca–Cl, Na–Mg–Cl to Na–Cl types. Hydrogeochemical evaluation showed that the salinity in the groundwater had geogenic sources mostly from the evaporitic formation in the study area. Bivariate plots of Ca²⁺/Na⁺ vs HCO₃ ⁻ and Ca²⁺/Na⁺ vs Mg²⁺/Na⁺ supported that evaporite dissolution and silicate weathering are the major sources of the salinity process in the Saveh Plain.