Assessing the Controlling Factors of Groundwater Hydrochemistry in Mond alluvial Aquifer, Bushehr

In this research, controlling factors affecting salinity of groundwater in Mond aquifer, Bushehr province, was studied. Electrical conductivity of water supply wells is varied between 1727 to more than 6000µs. Negative water balance is governed to aquifer because of two separate water exploitation zones. Lithology of surrounding formations, salt dome, saltwater intrusion and return flow of irrigation waters are factors that can contribute in water salinity. Using physical and chemical tests relating to 28 operating wells, the role of each of these factors in water salinity has been studied. Physicochemical characteristics and major elements (Na, K, Ca, Mg, Cl, SO4, and HCO3) were analyzed in these samples. Multivariate statistical methods were employed in assessing groundwater quality. The results show that, the main hydrochemical facies of the aquifer (Ca,Mg–SO4), represents 96% of the total samples. Clustering analysis shows two distinctive groundwater groups relevant to two different well fields. The results of factor analysis indicate that three factors explain about 83.3% total sample variance. The first and most important factor is mainly controlled by Gypsum dissolution in Fars group formation rounding Mond Plain. Dissolution of Halite and seawater intrusion is the second important source of salinity.