Sea Level Rise and Nuisance Flood Frequency Changes around the United States
In this report, we show that water level exceedances above the elevation threshold for “minor” coastal flooding (nuisance level) impacts established locally by the National Weather Service (NWS) have been increasing in time. More importantly, we document that event frequencies are accelerating at many U.S. East and Gulf Coast gauges, and many other locations will soon follow regardless of whether there is an acceleration of SLRrel. Lastly, we show a regional pattern of increasingly greater event-rate acceleration as the height between MSL and a location’s nuisance flood threshold elevation decreases.
Impacts from recurrent coastal flooding include overwhelmed stormwater drainage capacity, frequent road closures, and general deterioration and corrosion of infrastructure not designed to withstand frequent inundation or salt-water exposure. From this, we conclude that there is a time horizon, largely dependent upon the local rate of SLRrel, when critical elevation thresholds for various public/private/commercial serving systems will become increasingly compromised by tidal flooding. This concept of a non-linear impact trajectory needs to recognized, as it is critical for coastal planning to prevent degradation to society-serving systems at risk from SLRrel. The goal of this report is to heighten awareness of a growing problem of more frequent nuisance coastal flooding respective to a community’s living memory and to encourage resiliency efforts in response to impacts from SLRrel.