Groundwater quality evaluation of Shiraz City, Iran using multivariate and geostatistical techniques

Groundwater is vital water resource for domestic, agricultural and industrial purposes in Shiraz City, Iran. Management of groundwater with respect to quality and quantity is decisive subject in order to accomplish the increasing requirements for water. In the present paper, evaluation of groundwater parameters, viz., pH, electrical conductivity (EC), major cations (K+, Na+, Ca2+ and Mg2+), major anions (Cl- and HCO3-), NO3-, SO42-, total dissolved solids (TDS), alkalinity, hardness, sodium absorption ratio (SAR) and Na% were done from Shiraz City, Iran. Consequently, 80 groundwater samples were collected from different sites in June 2017.The results of different parameters were compared with the standard guideline prescribed by the World Health Organization (WHO) for drinking and public health purposes. From the results, it was concluded that 62.5% samples exceeded for EC values, 12.5% samples for Na+, 30% samples for Ca2+, 97.5% samples for Mg2+ and TDS, 28.7% samples for Cl-, and 40% samples for SO42- contents as recommended by WHO. The Na% values ranged from 5.25 to 38.59, whereas SAR values varied from 0.21 to 6.64 meq/L. Results of Na% and SAR indicated that groundwater is good for irrigation and domestic purposes. The results of MGI and BEI showed that 83.75% sampling sites showed shallow meteoric percolation type and Na + SO4 type with less than one value respectively. Multivariate statistical analysis (cluster analysis and principal component analysis) and spatial maps showed that both anthropogenic activities such as cement factory, gas power plant, Rishnnark factory and vegetable Oil Company, and natural processes like rock weathering are responsible for the contents of groundwater parameters.