Delineation and modeling of seawater intrusion into the Nile Delta Aquifer: A new perspective

Abstract

A comprehensive conceptual regional model for the Nile Delta aquifer has been composed in terms of the actual perspective of aquifer heterogeneity using all the new field data of drilled quality monitoring points in the Nile Delta aquifer. The study used the recently acquired configuration of the aquifer system which shows that the northern part the quaternary aquifer is devolved into multi-layered aquifer system while in the southern part; the aquifer consist of sand and gravel facies. The numerical modeling uses the finite difference SEAWAT program. The model is calibrated, both in terms of hydraulic heads and salt concentration, for the 2013 field data. The calibrated model is validated for the period 2013–2015. The model water balance reveals that seawater intrusion into the aquifer takes place at shallow to medium depths (up to 400 m), whereas groundwater fluxes in the deeper layers are moving toward the sea. The majority of the fluxes toward the sea help retaining old brine water in the deep zones and thus preventing seawater intrusion in these deep layers of the aquifer. This emphasizes the conclusion that the Nile Delta aquifer is not losing fresh groundwater flux to the sea. The study has achieved reliable necessary baseline simulation modeling and delineation of fresh/saline water interfaces as basis for decision-making and future management scenarios for controlled development of groundwater in the Nile Delta coastal aquifer.