As Hurricane Dorian gets closer to Florida, U.S. Geological Survey scientists have been in the field from Savannah, Georgia to Hollywood, Florida and on Florida’s Gulf Coast, deploying 175 storm-tide sensors [video] and16 other instruments that will track the hurricane’s effects.

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Between Thursday, August 29 and Saturday, August 31, hydrologists from the USGS’ Caribbean-Florida Water Science Center installed 125 storm-tide sensors in Florida. Eighty-five are in place along the state’s Atlantic coast from the Florida-Georgia state line to southern Broward County.

On Friday, field crews installed 40 more storm-tide sensors on Florida's Gulf Coast. Additional Gulf Coast deployments were curtailed on Saturday, after National Hurricane Center forecasters predicted Dorian would likely remain off the state's Atlantic coast. But the sensors installed at Captiva and Cape Coral, from Spring Hill to Sarasota, and from north of Steinhatchee to Inglis will remain in place until after the storm has passed. 

In Georgia, field scientists are installing 50 storm-tide sensors the length of the state’s low-lying coastline. Slow-moving Hurricane Dorian may cause higher-than-normal ocean waves well to the north of the storm, and its course is still uncertain. 

Most of the instruments are designed to measure the height and duration of the storm-tide as the storm approaches shore, makes landfall, and departs. Others will monitor water levels on inland water bodies, with some reporting water level data in near real-time; the field crews will gather data from them immediately after the storm has passed. The USGS’ Flood Event Viewer for Hurricane Dorian shows the location of the instruments that will record the storm’s effects on water levels as it moves onshore.

Storm surge, coastal erosion and inland flooding are among the most dangerous natural hazards unleashed by hurricanes, with the capacity to destroy homes and businesses, wipe out roads, bridges, water and sewer systems, and profoundly alter landscapes. The USGS has storm surge experts, as well as sophisticated equipment for predicting and monitoring flood and tide conditions, and has been consulting with the National Hurricane Center and other agencies to prepare for Hurricane Dorian.

Prepared to Capture Coastal Storm Surges

Storm surges are increases in ocean water levels caused by extreme storms. Scientists want to better understand storm surges so forecasters can more accurately model and predict surge-related flooding, engineers can design better storm-resistant structures, and emergency responders can work more safely and effectively.

The USGS’ network of storm tide sensors along portions of the U.S. Atlantic and Gulf coasts can record water level and barometric pressure every 30 seconds to document storm surge crests, or waves of water, as they make landfall. Anticipating a storm’s path and intensity, USGS scientists often deploy storm tide sensors at other places along the coast just hours or days before a hurricane’s expected landfall. The sensors are housed in steel pipes a few inches wide and about a foot long. Working quickly, and often in severe weather, field crews install them on bridges, piers and other structures that have a good chance of surviving a hurricane’s storm surge. 

The teams are also deploying barometric pressure sensors, one within ten miles of every storm tide sensor; the two devices work together to correlate the storm’s intensity with wave heights. The crews also plan to deploy five clusters of wave height sensors on boardwalks in Flagler, Volusia, Brevard, St. Lucie and Palm Beach counties. By recording wave heights along a line running from the beach to the dune peak and behind the dune, these transects help create a detailed picture of wave action.

Adding Temporary Streamgages to Track Dorian

The USGS Streamgaging Network operates scientific instruments that record water levels and other key pieces of information on rivers and streams throughout the nation, with the support of local, state, and federal agencies. During storms and floods the USGS uses this nationwide network to provide near-real-time data about water levels to the National Weather Service, Federal Emergency Management Agency, the U.S. Army Corps of Engineers, and others. 

When a major hurricane is expected to make a U.S. landfall, the USGS augments the network by installing special streamgages called rapid deployment gauges, or RDGs, in areas where flooding is likely, but no permanent streamgage exists. RDGs measure water levels and local weather data in areas susceptible to storm-tide flooding and transmit that information by satellite in near-real time for flood forecasting and emergency response. The public can see the information in near-real time by clicking on the RDG symbol in the Flood Event Viewer.

Field crews have installed eight RDGs in Florida. They plan to install 12 RDGs in Georgia, completing the work in advance of Hurricane Dorian’s winds, rain and storm waves. If flooding does occur, USGS field crews will make real-time streamflow measurements to verify the streamgages’ readings. After the storm passes, the crews will quickly replace any storm-damaged or lost gauges. During and right after hurricane flooding, these records help FEMA target emergency relief to the hardest-hit areas.

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Resources to Help Everyone Prepare

As USGS takes action to prepare for Hurricane Dorian, people in the path of the storm can get tips on creating emergency plans and putting together an emergency supply kit at www.ready.gov or www.listo.gov.