Determination of origin and distribution of saline water in the aquifer of Kharg Island, Iran

چکیده مقاله

Kharg Island with an area about 21.3 km² is located between 29° 12′ 22″ to 29° 16′ 29″ northern latitudes and 50° 16′ 54″ to 50° 20′ 12″ eastern longitudes. It is located 58 km to the northwest of Bushehr City in the southwest of Iran. The target of present paper is determination of origin and distribution of salt water in the shallow Kharg aquifer using hydrochemical and geophysical tools. More than 50 % of the island’s surface is covered by limestone. General direction of groundwater flow in the aquifer is from highlands to the eastern and the northern coasts. Exploitation of groundwater is carried out by shallow wells on the eastern part of Kharg Island. Sampling operations were conducted in 27 wells in May 2010. Saltwater intrusion mapping was conducted on the aquifer through combining the results of geophysical and hydrochemical studies. Hydrochemical factors such as bromide, bicarbonate, carbonate and chloride ions, electrical conductivity, and chloride to strontium ratio in addition to apparent resistivity confirmed similar seawater intrusion pattern in different parts of the aquifer. The results show that seawater is the main source of groundwater salinity but via two difference mechanism. The first mechanism of seawater intrusion is taking place in shore line. The second one is due to upconing as a result of extraordinary exploitation of product wells located in the west part of Kharg aquifer.