THE IMPACT OF SALTWATER INTRUSION AND SEA LEVEL RISE ON COASTAL COMMUNITIES: CORROSION, REPAIR COSTS, AND STRUCTURAL COLLAPSE RISKS IN MOBILE COUNTY, AL (Invited Presentation)

Coastal civil infrastructure is at risk from a changing climate, particularly from hurricane storm surges and coastal flooding which exert significant loads on structures. Additionally, saltwater intrusion (SWI) due to sea level rise (SLR) can cause building foundations to deteriorate. The impact of SWI on infrastructure foundations is not well understood and such damage is often unnoticed and uninsured, leading to unexpected expenses for property owners. In this presentation, we examine the effect of SWI from various SLR scenarios on the deterioration of building foundations, due mainly to corrosion of steel reinforcement, in approximately 137,000 residential buildings in low-lying areas around Mobile County, AL. The findings indicate a substantial risk of costly damage, with potential annual repair costs for these homes reaching up to US$90 million by 2100 under extreme SLR conditions.

In this presentation, we also analyze the combined impact of SLR and SWI on building systems to assess the risk of collapse of the above-ground structural system due to foundation deterioration. The deterioration of foundations weakens the overall structural integrity of the building superstructure. This combined hazard of flooding and SWI has a more severe impact than flooding alone. If flooding occurs after partial deterioration of the foundation, the buildings may lack the capacity to withstand the flood hazard. This increased vulnerability may lead to a higher probability of collapse. The results of our study highlight the need for comprehensive risk assessments that consider both flooding and SWI effects on coastal infrastructure.