A Review Study of Some Oceanographic Characteristics of the Shatt al-Arab Estuary, Southern Iraq

Abstract

The Shatt al-Arab Estuary is a unique environment in southern Iraq, as it is formed at the confluence of the Shatt al-Arab River with the Arabian Gulf. It is subject to both fluvial and marine influences, which result in daily changes in many oceanographic characteristics of its waters, in addition to seasonal variations.

This study presents an analysis of the oceanographic characteristics based on the findings of previous studies conducted in the estuary area. These characteristics include tides, salinity, discharge ratio, flushing time, mixing, circulation, stratification, and estuary classification. Changes in the hydrological conditions of the Shatt al-Arab River, represented by the decline in freshwater discharge to below 50 m³/s, have caused deterioration in the river and estuary environment by increasing the amount of salts entering from the Arabian Gulf, with values exceeding 12 g/L in the center of Basrah.

Furthermore, the decline in freshwater discharge has been reflected in the flow ratio, whose value did not exceed 0.1, giving the Shatt al-Arab Estuary the characteristics of a fully mixed estuary. The tidal phenomenon plays a major role in the hydrodynamics of the estuary as well as in the hydrology of the Shatt al-Arab River. It contributes to the mixing and circulation of water masses, leading to the disappearance of the characteristics of a stratified or partially mixed estuary from the classification and resulting in the formation of a fully mixed estuary.