Intensively exploited Mediterranean aquifers: resilience to seawater intrusion and proximity to critical thresholds

摘要

We investigate seawater intrusion in three promi- nent Mediterranean aquifers that are subject to intensive ex-ploitation and modi?ed hydrologic regimes by human ac-tivities: the Nile Delta, Israel Coastal and Cyprus Akrotiri aquifers. Using a generalized analytical sharp interface model, we review the salinization history and current status of these aquifers, and quantify their resilience/vulnerability to current and future seawater intrusion forcings. We iden-tify two different critical limits of seawater intrusion under groundwater exploitation and/or climatic stress: a limit of well intrusion, at which intruded seawater reaches key lo-cations of groundwater pumping, and a tipping point of com-plete seawater intrusion up to the prevailing groundwater di-vide of a coastal aquifer. Either limit can be reached, and ul-timately crossed, under intensive aquifer exploitation and/or climate-driven change. We show that seawater intrusion vul-nerability for different aquifer cases can be directly com-pared in terms of normalized intrusion performance curves. The site-speci?c assessments show that (a) the intruding sea-water currently seriously threatens the Nile Delta aquifer, (b) in the Israel Coastal aquifer the sharp interface toe ap-proaches the well location and (c) the Cyprus Akrotiri aquifer is currently somewhat less threatened by increased seawater intrusion.