Where is the freshwater-saltwater interface in offshore coastal aquifers?

The salt water intrusion (SWI) and submarine groundwater discharge (SGD) communities have traditionally approached coastal aquifers in different ways, but both communities agree on the importance of defining the mixing zone between freshwater and saltwater in coastal aquifers. The problem is that this mixing zone extends offshore in many aquifers, where it is very difficult to map. Laboratory and modeling studies of the freshwater-saltwater interface have generated very useful insights into fundamental processes but commonly struggle to incorporate the heterogeneity and temporal variability of real systems. This talk reviews current conceptual models and diverse evidence for offshore mixing zones, with recommendations for possible approaches moving forward.