A Geotechnical Perspective on High Tide Flooding: Exploring the Relationship Between Site Characteristics and High Tide Flood Impacts

High tide flooding (also known as “nuisance flooding” or “sunny-day flooding”) is recently occurring more frequently in response to sea level rise. Its impacts to infrastructure range from flooding of foundation systems and temporary sewage backups to saltwater intrusion in freshwater supplies and long-term failure of flood control structures. Although extensive data exists to characterize historical tidal flooding and models are available to predict future patterns, there remains a lack of understanding about the connection between geotechnical site characteristics and high tide flood impacts. Bringing a geotechnical engineering perspective to the issue of high tide flooding might improve risk assessment, regional planning, mitigation, and adaptation. To begin addressing these knowledge gaps, a group of coastal communities was selected to represent a variety of site conditions, and the degree and mode of tidal flood impacts was assessed for each community through a review of literature and case studies. Thereafter, relevant information were compiled for each community, including geotechnical data such as soil types, soil permeability, and groundwater table elevation, as well as high tide flood levels and current flood control strategies. These findings were compared with high tide flood impacts for each community, and emerging relationships between site characteristics and impacts were evaluated. Finally, a hypothesis regarding the impacts of geotechnical site characteristics on the severity of high tide flood impacts is formulated and recommendations for monitoring and future research steps provided.