Vertical Saltwater Intrusion in Coastal Aquifers Driven by Episodic Flooding: A Review

Abstract Low‐elevation coastal areas are increasingly vulnerable to seawater flooding as sea levels rise and the frequency intensity of large storms increase with climate change. Seawater can lead salinization fresh aquifers by vertical saltwater intrusion (SWI). Vertical SWI is often overlooked in zone threat assessments despite risk it poses critical freshwater resources salt‐intolerant ecosystems that sustain populations. This review synthesizes field modeling approaches for investigating practical theoretical understanding flushing processes obtained from prior studies. The synthesis explores complex dynamics influenced density‐dependent flow oceanic, hydrologic, geologic, climatic, anthropogenic forcings acting on across spatial temporal scales. Key knowledge gaps, management challenges, research opportunities identified help advance our vulnerability groundwater. Past studies focus idealized aquifer systems, thus future work could consider more diverse topographic environments. Concurrent programs should be sustained over time capture interactions between physical processes, repeated events, delayed responses. Finally, this highlights need improved coordination translation disciplines (e.g., engineering, hydrogeology, oceanography, social science) gain a holistic SWI. There also needs education communities, policy makers, managers motivate societal action address groundwater changing climate.