Anthropogenic and tidal influences on salinity levels of the Shatt al-Arab River, Basra, Iraq

Understanding the salinity variation caused by a combination of anthropogenic and marine sources is important for water resource management in heavily used rivers impacted by tidal influence. A quantitative analysis of intra-annual variability of salinity levels was conducted in the Shatt al-Arab River. Based on hourly records during 2014, the results showed high spatiotemporal variability in the range of 0.2-40.0 ppt. Similarities in salinity dynamics were used to divide the river course into four distinct spatial units to guide respective management actions. Salinity dynamics are influenced by different sources of saline water inflows and withdrawals associated with irrigation, industrial and municipal waste, marshes and by seawater intrusion. Adapting a simple interpolation approach, the measured distance of seawater intrusion was 80 km upstream the river mouth. Continuous monitoring of water quality can localize and assess the relative impact of the various salinity sources at different times. Managing seawater intrusion and any local effects should take into account variations in quantity and quality of irrigation return flows and wastewater discharges.