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Tens of millions of Americans live in areas vulnerable to hurricanes and tropical storms, many of whom are far from the coast. Flooding caused by these storms sometimes lasts weeks after they pass, often occurring hundreds of miles inland from where the storm made landfall.

Knowing where flooding is occurring, how significant it might be, and where waters are rising is critical information used to help protect people and communities. The U.S. Geological Survey provides this vital flood data via a nationwide network of more than 11,000 permanent streamgages installed along rivers, streams, lakes, and reservoirs. The USGS also has a smaller network of tide gauges that monitor tidally influenced bodies of water in select parts of the country.

The USGS streamgage network is one of the largest in the world and provides near real-time water levels and flows year-round at many key locations across the nation. USGS stream and tide gauge data on water levels and flows can play a crucial role in shaping critical decisions such as evacuation plans by emergency managers, coastal and inland flood forecasts by the National Weather Service, and flood-control decisions by the U.S. Army Corps of Engineers. The information gained from each storm also improves scientific understanding of storms and advances the USGS’s ability to inform decisions. This can help increase preparedness, reduce risk and enhance resilience for communities potentially affected by hurricanes and tropical storms.

Data from the stream and tide gauge networks are available online on the USGS National Water Dashboard. In addition to stream and tide gauge data, this interactive website also delivers real-time precipitation, atmospheric, water-quality and groundwater data from more than 16,000 USGS observation stations across the country.

To better track flooding events – like those often associated with hurricanes and tropical storms – in areas not monitored year-round by streamgages, the USGS utilizes specialized devices called “rapid deployment gauges.” As the name suggests, these temporary gauges can be installed quickly at critical locations to augment the USGS’s nationwide streamgage network.

Rapid deployment gauges provide near real-time information to the public and emergency managers tracking floodwaters. This can include data on water levels, precipitation, wind speed, temperature, humidity and barometric pressure, and are available on the USGS Flood Event Viewer. This online tool displays rapid deployment gauge locations and data for current and past events.  

Come back next week to learn how hurricanes and tropical storms can spread invasive plants and animals through floodwaters and how the USGS estimates their potential spread.

*Editor’s note: The image at the top of the story shows USGS scientist Scott Greenwood servicing a USGS streamgage on the St. Johns River near Sanford, Florida, after Hurricane Ian struck the Sunshine State. Photo by Gene Grimm, USGS.

Learn more about USGS hurricane science.

The USGS provides science for a changing world. Learn more at www.usgs.gov or follow us on Facebook @USGeologicalSurvey, YouTube @USGS, Instagram @USGS, or Twitter @USGS.