Comparing the Geo-Electric and Geo-Electromagnetic Methods in Determining Saltwater and Fresh Water Interference in the West and East of Babolsar Aquifer

Groundwater is one of the most reliable sources of available water for agriculture and drinking. In coastal areas due to saltwater intrusion, determining the interface between fresh and salt water for these area residents is very important. In this study, the characteristics of coastal aquifers was evaluated using geo-electrical and geo-electromagnetic methods in the eastern and western aquifers of Babolsar. These methods have high accuracy in this field. For this purpose in the study area, six sections in the coastline were chosen, in each section in the coastal line, 10 study points were selected with 50 meters distance, then, were selected five study points with 100, 200, 300, and 400 meters distance apart. In order to determine saltwater interface with geo-electric method, the observation wells were used. Regarding the observation data in many points, the results of the study methods showed that the geo-electromagnetic have high accuracy in comparison to the geo-electric method. Also, the results showed that the interface between saltwater and fresh water in the west of Babolsar sections are more than east of Babolsar sections. Overall, with regard to calculated interface depth in both regions, the saltwater intrusion exists and it is necessary to tackle saltwater intrusion in these areas using Best Management Practices.