Groundwater Assessment of Coastal Aquifers in Karachi: Impact of Seawater Intrusion

Adnan Khan^*, Asal EghbalBakhtiari

Department of Geology, University of Karachi, Karachi, Pakistan

* Corresponding author E-mail: adkhan@uok.edu.pk

Abstract: Present study is aimed at assessing the groundwater quality in coastal part of Karachi and detection of seawater intrusion through major ion geochemistry of the coastal groundwater occurring in Korangi and DHA areas. For this purpose 6 groundwater samples were collected from deep wells (mean depth: 600ft) of Korangi and DHA phase VIII. Groundwater pH is slightly variable which ranges between acidic to alkaline (6.6-8.5) with a mean of 7.7. The groundwater is classified as moderate to highly saline (mean TDS: 21234 mg/L) and very hard (hardness: 3221.3 mg/L). Hydro-geochemical analysis of collected samples revealed that the dominant hydrofacies in the groundwater is Na-Cl. In addition, excess of Ca and Mg followed by dominance of Cl over alkali ions suggest that the groundwater is highly saline mixed through sea water intrusion. The overall major ion chemistry reveals that such groundwater is not suitable for domestic purpose.

Key words: Groundwater quality, seawater intrusion, Major ion chemistry, Karachi coast