ABSTRACT
Discharge of fresh river water into the ocean is closely related to vertical and longitudinal salinity variations along an estuary. The Shatt al-Arab River (SAR) which discharges through its estuary at the border between Iran and Iraq into the Gulf is facing serious reductions in freshwater inflows upstream and from its tributaries, as well as significant seawater intrusion downstream. The alteration of river discharge also affects the estuarine ecosystem in terms of sediments, nutrients, dissolved oxygen, and bottom topography. The increases in salinity along the SAR, particularly caused by seawater intrusion, have become a threat to the people and environment alike. Generally, seawater intrusion makes the river water unfit for human consumption and unacceptable for irrigation practices. Besides seawater intrusion, human activities in the upstream part of the estuary also contribute to the salinity levels along the river.
