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Improve the self-purification of the Shatt al-Arab rivers system using simulation models

ABSTRACT The evaluation and control of pollution and self-purification processes in the river is one of the most important elements for implementing a purposeful and flexible strategy for managing a complex water system, because the response to the pollution of ecosystem depends on the river's ability to self-purification. So, in this research, the focus will be on the main six rivers system of the Shatt al-Arab in the city of Basra, which has many natural potentials to play a major role in the revival of the city. The problem of these rivers systems is that they have become stagnant swamps, where there is no continuous flow and renewal of their water by the phenomenon of the tides, due to the direct disposal of sewage and solid waste from the adjacent lands. In order to address this problem, the research hypothesized building a model that simulates water movement in this system to reveal the factors that affect the characteristics of their water flow, the locations where the water cycle is interrupted, the areas of concentration of sediments and contaminants and their propagation ranges. Through simulation results, appropriate planning and design treatments were proposed to restore the natural characteristics of these rivers, treat their pollution, improve their efficiency in self-purification. It also found that the sufficient time that river needs for self-purification were (18.11, 17.29, 18.29 h) for the three rivers Saraji-Khora, Ashar-Khandaq, Rubat-Jubaila respectively. While the discharge needed to provide self-purification and complete replacement during a full cycle tide were (5.9–12.3, 5.8–10.1, 4.88–7 m3/s) respectively.