Maximize the Benefits of ElBoghdady Outlet in Water Quality Status of LAKE MANZALA, EGYPT

Abstract

Lake Manzala is the largest coastal lake lies on the eastern north coast of Egypt and is considered the most valuable natural fish source. Water quality status and eutrophication levels of the lake had deteriorated due to the progressive increasing of polluted municipal, industrial and agricultural wastewater discharge from drains. The lake has many direct and indirect outlets to Mediterranean Sea but there were insufficient to the lake because of its great area. One of ineffective and indirect outlets to the sea is ElBoghdady outlet which lies 2.8 km away from the sea. The main objective of this work is to maximize the benefits of ElBoghdady outlet in lake water quality status by dredging 2.8 km radial channel to connect the outlet with the sea and other 10 km radial channel from outlet to inside the lake to increase water exchange between lake and sea. A hydrodynamic and water quality model for Lake Manzala was developed, calibrated and then modified to investigate the impact of this project in water quality status and eutrophication levels of the lake. The modified model simulated eight water quality parameters (BOD, DO, NO2, NH3, PO4, NO3, Chll_a and TP) as an indicator for water quality. The results show a significant improvement in lake water quality status and eutrophication levels. Significant decreases in the average concentrations of nutrients components by about 20%, were noticed, comparing to the original calibrated status of the lake (23.56%, 20.9%, 13.86%, 12.42% and 29.56% for PO4, NH3, NO2, NO3 and TP, respectively), While an increase in the average concentration of DO in the lake by about 1.74% was noticed.