Hydrodynamic and Ecological Modeling for Water Quality Assessment in Lake Qaroun, Egypt

Qaroun Lake, a closed salty lake in the Fayoum depression of Egypt, is an important natural resource that supports fishing, wildlife, and local communities. It mainly receives water from a dense drainage network, with some possible small contribution from groundwater. Since it has no outlet and loses water only through evaporation, its salinity keeps increasing. Any change in the amount or quality of incoming water strongly affects the lake’s environment. The environmental condition of Qaroun Lake was studied using the MIKE 21 model, Mike3, Eco Lab for water quality in addition to Transport modules to study contamination dispersion, which simulates water flow and quality. The study analyzed the changes in salinity, Biochemical Oxygen Demand (BOD), and Dissolved Oxygen (DO), then compared them with field measurements to support the analysis. The results showed very high salinity due to reduced inflow, high BOD from agricultural and domestic wastewater, and low dissolved oxygen caused by high temperature and salinity. These conditions threaten fish and other aquatic life. This study also evaluates lake water quality under a maximum contamination condition due to continued reuse of drainage network water. The study emphasizes the need for an ecological management plan to reduce pollution, improve water quality, and protect the lake’s long-term ecological balance and sustainability.