Sea Level Rise and Nuisance Flood Frequency Changes around the United States
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Material Information

Title:
Sea Level Rise and Nuisance Flood Frequency Changes around the United States
Creator:
National Oceanic and Atmospheric Administration
William Sweet
Joseph Park
John Marra
Chris Zervas
Stephen Gill
Publication Date:
Language:
English

Subjects

Subjects / Keywords:
Climate Change
Sea Level Rise
Floods
Drainage

Notes

Summary:
The National Oceanic and Atmospheric Administration (NOAA) water level (tide) gauges have been measuring water levels around the U.S. for over a century, providing clear evidence of sea level rise relative to land (SLRrel) around most of the continental United States and Hawaii. As SLRrel increases mean sea level (MSL), there is naturally an increase in tidal datum elevations, which are typically used to delineate inundation thresholds. Direct consequences of rising sea level against fixed elevations such as today’s built infrastructure also include increased inundation during extreme events both spatially and temporally. Not only are extreme flooding events reaching higher grounds and covering larger areas due to SLRrel, the frequency and duration of these extreme flood events are increasing. Another consequence of SLRrel is the increase in lesser extremes such as occasional minor coastal flooding experienced during high tide. These events are becoming more noticeable and widespread along many U.S. coastal regions and are today becoming more of a nuisance. As sea levels continue to rise and with an anticipated acceleration in the rate of rise from ocean warming and land-ice melt, concern exists as to when more substantive impacts from tidal flooding of greater frequency and duration will regularly occur. Information quantifying these occurrences to inform mitigation and adaptation efforts and decision makers is not widely available. 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.

Record Information

Source Institution:
Florida International University
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Aggregations:
Sea Level Rise