Impact of Burullus Lake on the Nile Delta Aquifer Overcoming Seawater Intrusion

Abstract

Surface recharge of coastal aquifers is one of the management tools to overcome seawater intrusion. The success of this management tool depends on the geological settings and the hydrogeological characteristics of the site. This study addressed the impact of Burullus Lake on the Nile Delta aquifer overcoming the seawater intrusion. The Lake resides on a clay aquitard with a thickness of 25 m or even more. Eight scenarios were proposed and simulated. These scenarios include decrease of the water salinity in the Lake, increase of the water level in the Lake and/or reduction of the clay cap thickness. The baseline salinity in the Lake is 9000 mg/L. The aquifer salinity varies with depth and proximity to the shoreline. The simulation of the baseline scenario indicated that the aquifer salinity within the Lake footprint ranges from 2000 mg/L to 7700 mg/L. When the water salinity in the Lake is decreased to 3000 mg/L and 650 mg/L, the aquifer salinity decreases more than 8.5% and 17%, respectively after 10 years at a depth of 50 m at a middle point of the Lake footprint. Although decreasing the water salinity in the Lake had decreased the aquifer salinity in the upper parts of the aquifer, the salinity increased with time in all scenarios. This is attributed to the effect of seawater intrusion. Reducing the thickness of the clay aquitard, by 10% or 20%, within the Lake footprint had minor effect on aquifer salinity.

Keywords: Coastal Aquifer, Burullus Lake, Seawater, Intrusion, Visual MODFLOW