Monitoring Storm Tide and Flooding From Hurricane Irma Along the U.S. Virgin Islands, Puerto Rico, and the Southeastern United States

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The U.S. Geological Survey (USGS), in cooperation with the Federal Emergency Management Agency, deployed a temporary monitoring network of storm-surge and barometric pressure sensors at 249 locations along the Puerto Rico, Florida, Georgia, and South Carolina coasts to record the timing, areal extent, and magnitude of hurricane storm tide and coastal flooding generated by Hurricane Irma.

Hurricane Irma path and intensity, September 2017

Hurricane Irma path and intensity, September 2017.

Hurricane Irma skirted the northern coast of the U.S. Virgin Islands and Puerto Rico as a Category 5 hurricane on the Saffir-Simpson scale (National Weather Service, 1972), with maximum sustained winds of 185 miles per hour (mi/h) on September 6, 2017 (fig. 1). The hurricane first made landfall near Cudjoe Key, in the lower Florida Keys, as a Category 4 hurricane with maximum sustained winds of 130 mi/h on September 10, 2017 (National Hurricane Center, 2017). The hurricane made a second landfall on Marco Island, Florida, as a Category 3 hurricane with maximum sustained winds of 115 mi/h on September 10, 2017 (National Hurricane Center, 2017). The hurricane left 23 percent of Puerto Rico (370,000 customers) and 59 percent of Florida (6.1 million customers) without power (U.S. Department of Energy, 2017).

The U.S. Geological Survey (USGS), in cooperation with the Federal Emergency Management Agency, deployed a temporary monitoring network of storm-surge and barometric pressure sensors at 249 locations along the Puerto Rico, Florida, Georgia, and South Carolina coasts to record the timing, areal extent, and magnitude of hurricane storm tide and coastal flooding generated by Hurricane Irma (fig. 2). Storm tide, as defined by the National Oceanic and Atmospheric Administration (2013), is the water-level rise generated by a combination of storm surge and the astronomical tide during a coastal storm. Storm surge is defined as the water-level rise, caused by a storm, over and above the predicted astronomical tide.

Location of storm-tide sensors for monitoring time, areal extent, and magnitude of storm tide and coastal flooding

Location of storm-tide sensors for monitoring time, areal extent, and magnitude of storm tide and coastal flooding generated by Hurricane Irma, September 2017.

The deployment of storm-surge and barometric pressure sensors and subsequent high-water mark (HWM) collection were completed as part of a coordinated Federal emergency response as outlined by the Robert T. Stafford Disaster Relief and Emergency Assistance Act (42 USC §5121 et seq.) under a directed mission assignment by the Federal Emergency Management Agency. In addition to the pressure sensors, a total of 508 HWMs were recovered and surveyed following the techniques described in Koenig and others (2016).

During the hurricane, real-time water-level data collected at temporary rapid deployment gages (RDGs, https://water.usgs.gov/hif/programs/projects/rapid_ deployment_gage_III/), long-term USGS streamgaging stations (https://waterdata.usgs.gov/nwis) with instrumentation used to measure water level and corresponding streamflow, and tide-gage stations were relayed hourly or more frequently, through satellite telemetry, for display on the Flood Event Viewer (https://stn.wim.usgs.gov/FEV/#IrmaSeptember2017). These real-time data provided emergency managers and responders with critical information for identifying floodaffected areas and accurately directing assistance to affected communities. Data collected during and following this hurricane and others (Frantz and others, 2017) can be used to calibrate and evaluate the performance of storm-tide models used to predict the maximum and incremental water level and flood extent and the site-specific effects of storm tide on natural and anthropogenic features of the environment.
 

References Cited

National Weather Service, 1972, The Saffir-Simpson Hurricane Wind Scale [Updated February 1, 2012]: National Hurricane Center web page, accessed February 27, 2018, at https://www.nhc.noaa.gov/aboutsshws.php.

National Geodetic Survey, 2017, Notice—NGS update, May 16, 2017, Technical details for GEOID12/12A/12B: National Geodetic Survey Geoid web page, accessed February 27, 2018, at https://www.ngs.noaa.gov/GEOID/GEOID12B/GEOID12B_TD.shtml.

U.S. Department of Energy, 2017, Hurricane Irma & Hurricane Harvey: U.S. Department of Energy Event Summary, Report No. 26, accessed at March 1, 2018, at https://energy. gov/sites/prod/files/2017/10/f37/hurricanes-irma-and-harvey-event-summary-26.pdf.

Frantz, E.R., Byrne, M.J., Caldwell, A.W., and Harden, S.L., 2017, Monitoring storm tide and flooding from Hurricane Matthew along the Atlantic Coast of the United States, October 2016: U.S. Geological Survey Open-File Report 2017–1122, 37 p., accessed November 8, 2018, at https://doi.org/10.3133/ofr20171122.