Investigating the Impacts of Dredging on Improving the Water Quality and Circulation of Lake Mariout via Hydrodynamics

Abstract

A two-dimensional hydrodynamic and water quality numerical flow model has been developed for Lake Mariout to simulate the flow pattern in the lake vicinity of the study area, the discharges and pollution loadings coming from the agricultural drains, and the point sources discharged directly to the lake. After the model development and calibration, different potential model scenarios were suggested for increasing the storage capacity of the lake’s basins and its impact on lake hydraulics, and therefore water quality conditions have been implemented. The first scenario was to study the deepening one or more basin and the effect of this deepening on water levels on different basins and the effect on the performance of El Mex pumping station and whether the pump station can lift the new lifting head or not. If there is an effect on the water surface of the lake, the model studied the optimum operation scenario for operating the El Mex pumping station. Also, different scenarios for high flood events have been studied and how shall flood water be stored in the basins and be lifted to the sea. Also, a study was carried on the possibility of using the Wadi Mariout as an emergency storage basin by connecting it to the current lake’s basins and its capacity to accumulate future floods. Finally, a scenario has been conducted on the diversion of inflowing drains for agriculture reuse and the inflow into the lake with evaporation compensation. The results indicated that 1 m dredging works in the northern, western, and southern basin would improve the circulation in the lake. Moreover, it will increase the storage capacity and will improve the water quality. Also, a connection between the southwestern basins with the salt basin will improve the water circulation and storage capacity of the lake.