Water quality modeling and management for Rosetta Branch, the Nile River, Egypt.

Rosetta Branch (RB) is the Nile western branch, which is considered the main freshwater resource for the western governorates of the Nile Delta, in addition to El-Beheira governorate, Egypt. This work aims to investigate the effectiveness of applying six feasible water quality management scenarios for the RB at Kafr Elzayat (KZ) City, where two major pollution sources (industrial companies and the Tala Drain) are discharging their effluents to the branch. A hydro-ecological model for the branch was developed based on MIKE 11 modeling system (3 modules). The developed model was calibrated using field hydrodynamic and water quality records for the branch during the period from November 2014 to August 2015. The calibrated model results were considered a base case for the simulated management scenarios. According to the study results, diverting the Tala Drain effluents to the nearest main drain will significantly enhance the branch water quality, while diverting of the industrial companies' effluents to the city sewer system will significantly enhance the water quality conditions downstream of the study. The expected scenario of decreasing the RB discharge, due to future climatic changes and/or construction of the new Ethiopian dams, will significantly affect the RB water quality status in a negative way. Urgent management plans, based on the presented scenarios results (or a combination of them), should be applied to enhance the branch water quality. The Tala Drain should be, at least, provided by a water quality treatment plant, and the branch freshwater discharge should be increased.