Water Quality Mitigation Scenarios for Burullus Coastal Lake, Egypt

Abstract

Lake Burullus is the second largest coastal lagoon in Egypt, its ecosystem has been deteriorated, due to its central location inside the Nile Delta. The lake receives most of the drainage water of the Nile Delta region through eight agricultural drains. The drainage water which discharged into the lake is mostly nutrient-rich fresh water, polluted with agricultural fertilizer and heavy metals from industry. Lake Burullus is classified as hypereutrophic with bad to very bad environmental conditions. The main objective of this study is to investigate the feasibility of applying different water quality management scenarios to improve the lake ecosystem. A calibrated hydrodynamic and water quality model for the lake was developed using a two-dimensional, vertically averaged, finite difference hydrodynamic and ecological code, MIKE21. This developed model was calibrated with measured field data collected during the period (June 2010–July 2011). Three hydrodynamic parameters and five water quality parameters of the lake were chosen to present the study results. These parameters are: water levels, water temperature, salinity, dissolved oxygen, biochemical oxygen demand, nitrate, Ammonia and ortho-phosphate. Three enhancing water quality scenarios for the lake were investigated: an additional artificial outlet, treatment plants for drains discharge and constructing of radial channels in lake bed. The study results verified that, economically, treatment plants scenario for the two most polluted drains is highly recommended. Constructing of an additional outlet will increase the average lake salinity and is considered as the most effective scenario for enhancing the DO concentrations in the lake. A water quality management strategy is urgently required for the lake ecosystem.