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September 13, 2017

Hurricane Irma’s heavy rains and storm surge caused severe flooding in parts of the Southeast.

To learn more about USGS’ role providing science to decision makers before, during and after Hurricane Irma, visit the USGS Hurricane Irma page.


Reporters can accompany USGS crews as they repair and check streamgages, measure streamflow, collect high water marks and/or retrieve the storm surge sensors from various locations along the Gulf and Atlantic coasts.

Points of Contact

Florida: Mark Dickman,, cell (954) 849-4465

            Kevin Grimsley,, cell (813) 267-2321

            Darrell Lambeth,, cell (407) 367-8831

Georgia: Chris Smith., cell: (678) 953-1604

South Carolina: Tim Lanier,, cell:(803) 727-9040


Hurricane Irma’s heavy rains and storm surge caused severe flooding in parts of the Southeast. Some rivers and streams have yet to crest as water moves through tributaries into larger rivers. Hurricane response crews from the U.S. Geological Survey are in Florida, Georgia and South Carolina repairing and checking streamgages, making high flow measurements and retrieving storm-tide sensors now that Hurricane Irma has passed.  

Measuring the Flow

Over the next several days  the USGS will be making streamflow measurements that will help determine the magnitude and extent of the flooding. Later, the information will help homeowners and insurers recover from their losses, help FEMA map the flood plains where property is at risk, and help scientists improve future flood forecasting.

The Height of the Water

High water mark data collected from Hurricane Irma will allow FEMA to revise its current maps for the affected areas. This data is also part of the flood frequency calculations that FEMA uses to identify areas that are likely to experience high water in the event of a flood that has a 1 percent chance of happening in any given year. These floods, known as 100-year floods, serve as the foundation for flood management planning.

Another significant use for these high-water marks is the USGS Flood Inundation Mapping effort. A flood inundation map library is a set of maps that shows where flooding may occur over a range of water levels in the community’s local stream or river.

Inundation maps are one factor used to determine where changes should take place in building codes to help communities be more resilient; where evacuation routes should be; where (and how high) a bridge or road should be; and other community planning efforts. Once these flood inundation maps are complete, they’re uploaded to the USGS Flood Inundation Mapper, which allows users to explore the full set of inundation maps that shows where flooding could occur given a selected stream condition. Users can also access historical flood information and potential loss estimates based on the severity of the flood.

 Robert Everett deploying HOBO MacIntosh County, GA
(Public domain.)


USGS crews will be retrieving storm-tide sensors from along the coasts of Florida, Georgia and South Carolina, and begin to analyze the data as part of a FEMA Mission Assignment. The information will help define the depth and duration of the storm-surge, as well as the time of its arrival and retreat. That information will help assess storm damage, discern between wind and flood damage, and improve computer models used to forecast future floods.

 These storm-tide sensors, housed in vented steel pipes a few inches wide and about a foot long, were installed on bridges, piers, and other structures that had a good chance of surviving a storm surge during a hurricane.  You can review the storm-surge sensor deployment and see some of the incoming data via the USGS Flood Viewer at

 Learning from Irma’s Impact

The USGS studies the impacts of hurricanes and tropical storms to better understand potential impacts on coastal areas. Information provided through the sensor networks provides critical data for more accurate modeling and prediction capabilities and allows for improved structure designs and response for public safety.

The USGS, in cooperation with state and federal agencies, also operates more permanent sensor networks installed along the East Coast of the U.S. These networks provide real-time data important to the National Weather Service, FEMA and other USGS partners involved in issuing flood and evacuation warnings and in coordinating emergency responses to communities.

To stay up-to-date on Hurricane Irma science from the USGS visit:


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