Assessment of hydraulic connection between Kashan aquifer and adjacent salt lake and determination of salinity source in the aquifer

Shortage of fresh water resources and salinization of aquifers are two major development challenges in arid and semi-arid regions. Population growth, industry development, agricultural development in order to provide the required food resources and climate change has increased the uncontrolled abstraction of groundwater resources, which in turn has led to a decrease in groundwater quality, especially in arid and semi-arid regions. The purpose of this study is to investigate the main reasons for salinization of Kashan aquifer, one of the critical aquifers in Isfahan province, which is located near the salt lake. For this study, 53 wells located in Kashan aquifer were investigated. After selecting wells with suitableconditions, 74 water samples were collected from selected wells and chemically and ionically (EC, Na +, K +, Ca2 +, Mg2 +, Cl-, HCO3-) were studied. According to the results, the direction of groundwater flow in this aquifer is from the west to the east of the aquifer, with the exception of the northeastern region of the aquifer where there is a return flow from the salt lake to the inside of the aquifer. The results of this study showed that salinity of Kashan plain aquifer in different regions has two main reasons: in the central and southern regions of the aquifer, the reason for salinity is the uncontrolled abstraction of groundwater from exploitation wells, conical rise of saline water and the occurrence of upconing phenomenon. In the northeastern regions of the aquifer, there is a return flow from the salt lake and the intrusion of salt water into the aquifer.