Seawater intrusion processes, investigation and management: Recent advances and future challenges

► We review seawater intrusion literature and offer future research directions. ► The degree of spatiotemporal heterogeneities needed in management models is unknown. ► Process understanding requires more comprehensive seawater intrusion measurement. ► Methods are needed to routinely obtain the uncertainty of seawater intrusion models. ► Seawater intrusion is an active research field with substantial unresolved issues.