Chronic and Acute Coastal Flood Risks to Assets and Communities in Southeast Florida

Abstract

Chronic and acute coastal flood risks in Miami-Dade County are assessed over the range of sea-level rise (SLR) scenarios for the coming decades. The HAZUS-MH coastal flood hazard modeling and loss estimation tool are used to determine flood extent and depth and corresponding monetary losses to buildings associated with different sea water levels (SWLs). The frequency of SWLs is estimated using a nonstationary mixture normal-generalized Pareto distribution under current condition and future SLR scenarios. Also, the least adaptation level to cope with SLR-induced amplification of coastal flooding is assessed in terms of an increase in flood threshold. The results indicate that under current sea-level conditions, coastal flood risks are predominantly from exposure to acute extreme events. However, chronic risks from repetitive nonextreme flooding may exceed those from extreme floods under future SLR scenarios. Therefore, adaptation strategies may incorporate consideration about chronic flooding to avoid increasing cumulative losses under future SLR scenarios.