Isotopic and Chemical Composition of Egypt’s Groundwater Resources

Aquifers in arid regions are mostly the sole sources of freshwater under the limited surface water resources. Therefore, they are affected by diverse natural and anthropogenic pressures resulting in over-exploitation and quality degradation. Investigating the spatial variability in isotopic and chemical compositions of these aquifers provides a better understanding of the recharge and contamination sources and mechanisms and ultimately guides the sustainable management scenarios of these aquifers. In this chapter, we compiled all historical isotopic (hydrogen and oxygen) and chemical (salinity) compositions of all groundwater samples collected for seven aquifer systems in Egypt (alluvial, Nile Valley and Nile Delta, coastal, Moghra, carbonate, Nubian, and fractured basement). The water chemical and isotopic compositions were then used to provide an improved understanding of the country-wide groundwater resources’ isotopic and chemical compositions and to investigate the recharge and contamination sources and mechanisms. This study also provides sustainable management scenarios for the seven Egyptian aquifers.