Impact of sea-level rise on saltwater intrusion length into the coastal aquifer, Partido de La Costa, Argentina

•The impact to groundwater of a potential 1-m rise in sea level was studied.•Under head-controlled model the interface migrates landward between 25 and 40 m.•Under flux-controlled model the interface migrates landward more than 200 m.•Due to hydrological parameters southern area is more sensitive to saltwater intrusion.•Reduction in recharge will have the greatest impact on saltwater intrusion lengths.

The impact to water resources of a potential 1-m rise in sea level against the low-lying coast of Partido de La Costa, Argentina was modeled using two scenarios. The first scenario was calculated under the assumption of a constant lateral flux of freshwater. A constant water-table elevation was assumed in the second scenario. Maintaining the lateral flux of freshwater from the land (the first scenario) resulted in an approximately linear increase of the inland extent of saltwater intrusion with rising sea level; saltwater penetrated landward between 25 and 40 m. Meanwhile holding the water-table elevation constant (the second scenario), caused the movement of the saltwater interface to be non-linear. In this case, landward migration in excess of 200 m or more might be expected. The second scenario is more likely to be the situation in Partido de La Costa. The variation of hydrogeological parameters from north to south along the barrier conspire to make the southern reaches, where both the hydraulic conductivity and aquifer thickness are greater, more sensitive to saltwater intrusion from sea-level rise than the northern part of the barrier. These findings may be applicable to similar sandy coastal aquifers in other parts of the global coastline.