Lake Manzala lies on the eastern north coast of Egypt and is considered as the largest Egyptian coastal lakes. Economically, Lake Manzala is considered as one of the most valuable fish sources in Egypt. The water quality status of the lake has been degraded due to the progressive increasing of industrial, municipal and agricultural wastewater discharge from six main drains. The lake has three main effective outlets, one to Suez Canal and the others to the Mediterranean Sea. A new project has been started in Lake Manzala to improve the sea-lake water exchange by dredging the two main lake outlets to the sea and constructing two radial channels from the lake to the sea passing through the two main outlets. In this work, a hydrodynamic, advection dispersion and water quality model for Lake Manzala was developed, based on MIKE21 modelling system. Eight water quality parameters were simulated (BOD, DO, Chll_a, NO₂, NO₃, NH₃, PO₄, and TP), in addition to three hydrodynamic parameters (water depth, water temperature and salinity). The model results show good agreement with the observed water depth, water temperature, salinity and water quality records. The calibrated model was used to investigate the impacts of radial channels on Lake Manzala hydrodynamic and water quality characteristics. The results show a significant improvement in the lake water quality status. Significant decreases in the average concentrations of some water quality parameters were noticed, comparing to the original calibrated status of the lake (-21%, -14%, -13% and -10% for PO₄, NO₂, NH₃ and Chll_a – as examples). While an increase in the average concentration of DO in the lake by about 1% was noticed. Other water quality improvement scenarios for the lake should be investigated, in addition to the investigated scenario of radial channels, using the lake developed model.