Muscat – Researchers at Sultan Qaboos University (SQU) have mapped a large wedge of seawater extending into a coastal aquifer in northern Oman, providing a new baseline for monitoring a threat that has damaged groundwater quality and affected agriculture.

The study, carried out in Al Jifnain between Al Jifnain Dam and the Sea of Oman, found the saline body was thickest near the shoreline and gradually thinned farther inland.

Led by Dr Muhammad Younis Khan, Assistant Professor of Applied Geophysics at SQU’s College of Science, the research used advanced geophysical imaging to distinguish freshwater from saline groundwater beneath the area.

Groundwater is a critical resource in Oman, particularly for agriculture, but coastal aquifers are vulnerable to seawater intrusion when excessive extraction alters the natural balance between freshwater and the sea.

Dr Khan said deterioration in groundwater quality has led to wells being abandoned and affected economically important crops, including date palms.

Researchers used the Transient Electromagnetic (TEM) method combined with Laterally Constrained Inversion (LCI) to create detailed images of underground conditions.

The models identified near-surface gravels, a freshwater-bearing gravel aquifer and localised clay-rich layers. Most importantly, they revealed the large wedge-shaped highly conductive zone interpreted as seawater intrusion.

According to Dr Khan, combining the two techniques produced more continuous and geologically realistic images than conventional processing, allowing researchers to better differentiate freshwater, saline water and clay.

The findings could also help assess whether managed aquifer recharge using water from Al Jifnain Dam can protect freshwater reserves over the long term.

Dr Khan recommended repeated TEM surveys alongside groundwater-level and hydrochemical measurements to track changes in salinity. He also called for groundwater-flow modelling and high-resolution airborne electromagnetic surveys to produce three-dimensional maps of salinity.

Such monitoring could help authorities identify changes before further deterioration occurs and support decisions on groundwater extraction and aquifer recharge.

Published in the peer-reviewed journal Water, the research was conducted by Dr Khan, Dr Talal Al Hosni, Prof Osman Abdalla, Bader Al Shaqsi, Dr Hai Li and Dr Ahmed M Beshr.