When a major storm threatens to make landfall in the United States or its territories, the USGS provides comprehensive scientific capabilities and information that decision makers, emergency responders and communities can use to help them prepare, cope and recover from a storm.
This includes the USGS’ ability to forecast coastal change; track storm surge, river and stream levels and flow; measure coastal and inland flooding across entire regions; capture high-resolution ground elevation and topographic data; and create detailed maps used by disaster teams responding in the aftermath of storms.
U.S. Geological Survey scientists are ready to respond to a hurricane or tropical storm well before the red-and-black storm warning flags unfurl. Starting about three days before a coastal storm’s predicted landfall, the USGS begins collecting data that can improve forecasting, guide relief work, and speed up recovery from the powerful storms’ effects.
Storm tides, 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, alter landscapes and reshape the nation’s coastline. The USGS has experts in these hazards ready to provide their expertise and to support the relief and recovery effort.
During the hurricane season, the USGS Coastal Storm Response Team, made up of a multidisciplinary team of specialists throughout the USGS, works closely with the National Hurricane Center and other federal agencies and confers daily when forecasters indicate that a hurricane or tropical storm is likely to make landfall in the U.S.
The Storm Team decides the timing and extent of the USGS’ storm response based on the storm’s forecast intensity and track. Once it’s determined a hurricane or tropical storm will likely strike somewhere in the U.S., the team leaders decide whether it is necessary and safe to deploy USGS field crews to the storm’s projected path along the coast. If deployed, one of the main tasks for the field crews is to install special water-level measuring instruments called storm tide sensors. These sensors record data that track storm tides and coastal flooding. This information helps USGS and NOAA scientists improve storm surge and coastal change forecast models. It also helps FEMA and other federal, state and local agencies’ relief efforts by pinpointing the areas hardest hit by storm tide flooding.
These storm tide sensors, housed in vented steel pipes a few inches wide and about a foot long, are part of the USGS Storm Tide Monitoring Network. The storm tide sensors are designed to be rapidly installed on bridges, piers, and other structures that have a good chance of surviving a hurricane. The sensors collect water pressure readings that help define the depth and duration of a storm tide, the time of its arrival, and its retreat. That information helps public officials assess storm damage, tell the difference between wind and flood damage, and improve computer forecast models.
USGS crews also install rapid deployment gauges at locations that are not monitored year-round, but are at risk of flooding due to an approaching storm. These RDGs provide real-time information to emergency managers tracking floodwaters, such as water level, precipitation, wind speed, humidity and barometric pressure.
RDGs can be quickly installed at critical locations when needed, which helps augment the USGS’ nationwide real-time network of about 8,500 streamgages that transmit both streamflow and water levels and another 1,700 streamgages that transmit just water levels. The National Weather Service uses data from streamgages that provide both water level and streamflow to develop flood forecasts, and the U.S. Army Corps of Engineers uses these data to make flood-control decisions. The streamgages that provide only water levels are used by local agencies to track flood locations and plan emergency response and allow the public to monitor local rivers and stream levels in real time.
The public can track storm tide sensor and RDG deployments and view past storms on the USGS Flood Event Viewer and see USGS streamgage readings in real time on both the viewer and the USGS National Water Information System.
Forecasting Coastal Change
Before a storm’s expected landfall, USGS coastal change experts forecast how a storm may reshape the coastline using a sophisticated system they developed called the coastal change hazard forecast model.
The model provides detailed forecasts of a strong storm’s likely effects on sandy shorelines along the Atlantic and Gulf coasts. It predicts where protective sand dunes are likely to be eroded at their bases or overtopped by storm waves and where coastal areas behind the dunes could be inundated by seawater.
These forecasts can help emergency managers decide which areas to evacuate, which roads to use, and where to position heavy equipment for post-storm clean-up. The forecasts begin 48 hours before a storm is expected to make landfall and are updated based on the latest forecasts from the National Hurricane Center. The forecasts are available to the public at the USGS Coastal Change Hazards Portal.
Tracking Flood Effects
Hurricane rains can cause flooding far from the coast. To track inland flooding, the USGS gathers data from its network of streamgages, as well as from rapid deployment gauges. When flooding occurs, USGS field crews make real-time streamflow measurements to verify streamgage readings. The crews also quickly replace storm-damaged or lost gauges. During active flooding the National Weather Service uses USGS streamgage data to refine the timing and severity of flood forecasts downstream. USGS streamgages also help the Federal Emergency Management Agency target emergency relief to the hardest-hit areas. You can track storm tide sensor deployment and see streamgage readings in real time at the USGS Flood Viewer.
Maps and Apps That Show the Big Picture
The USGS strives to ensure that the disaster response community has rapid access to timely, accurate, and relevant geospatial imagery, products, and services before, during, and after a hurricane or other disaster. The USGS Earth Resources Observation and Science Center provides access to remotely sensed imagery and geospatial datasets in response to requests from agencies engaged in disaster response. These products enable agencies to plan the response to conditions on the ground. The USGS Hazards Data Distribution System facilitates the sharing of imagery and other geospatial datasets.
During a disaster like a hurricane or tropical storm, first responders often rely on the USGS National Geospatial Program, which collects, archives and shares digital records on the nation’s topography, natural landscape and human-made environment. The program’s Geospatial Information Response Team, also known as the GIRT, works within the USGS and with partner agencies to provide key information to federal, state and local agencies, emergency managers and first responders. The information is shown on multi-layered websites or on printed maps that provide a big-picture view of a storm’s impacts, or a close-up of a specific community.
Using a web app designed to help storm team members, scientists, and others working on storm response, the team collects and makes available key pieces of information, such as the storm’s track, the USGS facilities that lie in its path, lidar elevation data, detailed local maps and more. The app is designed to provide managers with a basic overview of the information they need to understand the situation and respond to it effectively.
The GIRT also works with the USGS Earth Resource Observation and Science Center to coordinate the archiving of place-based storm data, from high water marks to photographs, and make it accessible. The team continues to add new features to the websites and printed maps created for individual storms, giving emergency managers, decision makers and first responders access to the most relevant and updated information available.
Collecting and Assessing Flood Data
Once the storm danger has passed, USGS field crews will travel to the affected areas to make real-time streamflow measurements, verify the accuracy of streamgage readings and quickly repair or replace damaged or lost gauges. Crews will also search areas affected by flooding for high-water marks, which are used by scientists to determine how high the flood waters reached.
These data help insurers and property owners document damage, help affected areas rebuild, and inform the forecasting, response, and recovery efforts of agencies like the National Weather Service, the Federal Emergency Management Agency, and the U.S. Army Corps of Engineers. They also provide real-world information to update the USGS’ flood inundation maps, and help improve forecasts for future disaster response.
In order to analyze the data gathered in the field after a storm, USGS scientists need accurate, detailed information about land elevation, which is provided by the USGS 3D Elevation Program. That program collects data using lidar - a technique that uses light pulses to produce high resolution elevation imagery - over the United States and its territories. These data are used for mapping storms’ flood inundation, modeling storm surge, evaluating topographic changes like beach and dune erosion, and pinpointing damage to buildings and other infrastructure. Up-to-date elevation data are also essential for infrastructure repair and redevelopment after a storm.
The USGS 3D Elevation Program acquires this data across the country and makes it publicly available on The National Map.
Understanding and Documenting Coastal Change
USGS coastal change scientists use aircraft and drones to collect thousands of high-resolution aerial photographs of the nation’s coastlines to document coastal changes before and after a major storm strikes. Scientists use this imagery and an advanced technique called "Structure-from-Motion" to estimate beach and dune elevations from a series of overlapping images. This allows the team to document how sand dunes changed during the storm and to improve the coastal change forecast models’ future forecasts.
Information for the Future
From beginning to end, USGS science informs and assists the response to major storms. Whether through modeling and forecasting, mobilizing teams around the country to help where they’re needed, responding to emergencies, or assisting other agencies, the USGS will continue to weather whatever storms may come.
For more information please visit these additional websites:
Ready.gov for children— What to do before, during and after a hurricane
USGS Coastal Change Hazards: Hurricanes and Extreme Storms – Information on coastal change
USGS Flood Information—Information about current and past flooding
USGS WaterAlert – Sends email or text messages from the USGS streamgage of your choice
USGS WaterWatch— Provides current USGS water data for the nation