Encroaching Tides

The report analyzes 59 tide gauges along the U.S. East and Gulf Coasts to project the impact of sea level rise on tidal flooding. Using an Intermediate-High scenario from the National Climate Assessment, the analysis finds that at least 40 locations will see a doubling of coastal flooding events by 2030, with the majority experiencing a 10-fold increase by 2045. Additionally, nearly half of the evaluated locations are projected to experience moderate coastal floods by 2045 from tides that currently only cause minor flooding.

• Under an Intermediate-High sea level rise scenario, at least 40 of the 59 investigated locations on the East and Gulf Coasts are projected to experience at least double the number of coastal flooding events by 2030.
• By 2045, most of the evaluated locations are projected to see a 10-fold increase in the frequency of flooding.
• Tidal floods are expected to increase in severity; by 2045, nearly 50% of the evaluated sites will experience moderate coastal floods from tidal fluctuations that currently only trigger minor floods.
• The analysis utilized 59 NOAA National Ocean Service tide gauges, provided they had a defined minor flooding threshold and were available in the NOAA Inundation Analysis tool.
• The study verified the accuracy of flooding thresholds by correlating Inundation Analysis events with Coastal Flood Advisories; 52 of the 59 gauges showed a correlation of 66% or higher.
• Historical analysis of the Sewells Point tide gauge in Norfolk shows a roughly 5-fold increase in the number of days with flood events since the 1970s.

APA

Spanger-Siegfried, E., Fitzpatrick, M., & Dahl, K. (2014). Encroaching Tides. Union of Concerned Scientists. https://www.ucs.org/sites/default/files/attach/2014/10/encroaching-tides-technical-appendix.pdf

Chicago

Spanger-Siegfried, E., M.F. Fitzpatrick, and K. Dahl. Encroaching Tides. Union of Concerned Scientists, 2014. https://www.ucs.org/sites/default/files/attach/2014/10/encroaching-tides-technical-appendix.pdf.

Wikipedia

{{cite report |last1=Spanger-Siegfried |first1=E. |last2=Fitzpatrick |first2=M.F. |last3=Dahl |first3=K. |title=Encroaching Tides |publisher=Union of Concerned Scientists |date=October 2014 |url=https://www.ucs.org/sites/default/files/attach/2014/10/encroaching-tides-technical-appendix.pdf |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{spangersiegfried2014encroaching, author = {Spanger-Siegfried, E. and Fitzpatrick, M.F. and Dahl, K.}, title = {{Encroaching Tides}}, institution = {Union of Concerned Scientists}, year = {2014}, month = oct, url = {https://www.ucs.org/sites/default/files/attach/2014/10/encroaching-tides-technical-appendix.pdf}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }