Impact of Climate Changes on Seawater Intrusion in the Nile Delta Aquifer (Egypt)

Climate change is one of the most significant natural processes and a serious threat to humankind, because it results in a rise in sea levels, a reduction in precipitation, and an increase in surface water evaporation. Coastal aquifers, which are a significant supply of freshwater in arid and semi-arid regions, are one of the areas most impacted by this phenomenon. Increased abstraction from coastal aquifers also reduces freshwater runoff into the ocean. As a result, there is an increase in inland seawater intrusion, and wells are contaminated by lowering water quality through increasing salinity. One of these aquifers is the Nile Delta aquifer (NDA) in Egypt, one of the world’s largest groundwater aquifers with an area of about 22,000 km2. This aquifer is exposed to severe seawater intrusion from the Mediterranean Sea. The primary goals of this study are to apply the numerical models; Visual MODFLOW and SEAWAT to examine how climatic change would affect seawater intrusion in the NDA. In this study, Visual MODFLOW is used to simulate groundwater head. A groundwater model for the NDA was created using the SEAWAT program to simulate the intrusion of saltwater. In addition to the basic case, six other scenarios have been added considering a combination of sea level rise (SLR) and change in the withdrawal rate. A comparison between the Equi-concentration line 1,000 ppm which represents the freshwater line of the base case for the current study, and the Equi-concentration line for 1960, 1980, and 1992 is examined to study the creep of saltwater. The comparison revealed that the creep occurs in the west and middle of NDA but lagged toward the east. The results showed that the sixth scenario, which assumed sea level rise by 0.5 m and double the base case abstraction rate, is the worst scenario. Therefore, the withdrawal from wells must be reduced or at least maintained at the same rate, and the shore protection methods should be used to prevent the advancement of the shoreline.