September is National Preparedness Month, a time for Americans to review their preparedness plans for disasters or emergencies in their homes, businesses and communities. It’s also historically the peak of hurricane season.
September is National Preparedness Month
USGS Ready and Responding to a Very Active Atlantic Hurricane Season
Early Thursday morning Hurricane Laura made landfall in Cameron, Louisiana as a Category 4 hurricane, with sustained winds of over 150 mph. Laura marks the 13th named storm of the 2020 Atlantic Hurricane Season, which has included four hurricanes and nine tropical storms. For a storm to be named it must have winds of 39 mph or greater.
And the season is likely to get even busier. The National Oceanic and Atmospheric Administration recently updated their forecast and now predicts the season will have 19-25 named storms, up from their previous forecast of 13 to 19. Seven to 11 of the predicted storms this season could become hurricanes with winds of 74 mph or higher. Three to six of the hurricanes could become major hurricanes with wind speeds of 111 mph or greater.
With half of the hurricane season still to go, it’s a good time to learn about hurricane preparedness by visiting Ready.gov or Listo.gov (en Español). In the meantime, the U.S. Geological Survey stands ready to provide the science to decision-makers that can help guide efforts to protect lives and property if another hurricane or tropical storm makes landfall this season.
Tropical storms, hurricanes and other large coastal storms can impact seaside and inland communities and ecosystems with high winds, storm surge, erosion and flooding. These forces can destroy buildings, roads and bridges and reshape the nation’s coastline.
When a major storm threatens to make landfall in the U.S. 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 with and recover from a storm. This includes the USGS’s ability to forecast coastal change; track storm surge, river and stream levels and flow; capture high-resolution ground elevation and topographic data; create detailed maps that can be used by disaster teams responding in the aftermath of storms; and measure coastal and inland flooding across entire regions.
Forecasting Coastal Change as a Hurricane Approaches
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 make critical decisions before a major storm strikes, including which areas to evacuate, which roads to use and where to position storm-cleanup equipment. The forecasts typically begin 72 hours before a storm is expected to make landfall, are updated based on the latest forecasts from the National Hurricane Center and are available at the USGS Coastal Change Hazards Portal. The site has recently been updated with new coastal elevation data that reflect sandy shoreline changes resulting from recent hurricanes and new scenarios of storm-induced erosion. This allows forecasts for the 2020 Atlantic Hurricane Season to be based on the latest information available.
Working with the National Weather Service, the coastal hazards storm team also updates forecasts for certain areas several times a day using real-time water levels from the weather service’s Nearshore Wave Prediction System. The team’s Total Water Level and Coastal Change Forecast Viewer displays results from a new model that currently covers about 1,865 miles of coastline in select areas from Florida to Maine. The model predicts the timing and height of water levels at the shoreline and potential impacts to coastal dunes. NOAA will use the predictions to help inform forecasters at the National Hurricane Center. As the program's coverage area expands, the predictions will also be made available to National Weather Service forecasting offices and the public.
“We are working on expanding the Total Water Level Viewer to include the Gulf coasts of Texas, Alabama and the Florida panhandle, as well as additional areas along the Atlantic coast which will give us about 2,900 miles of total coastline coverage,” said oceanographer Kara Doran, USGS Coastal Change Hazards Storm Team leader. “We hope the new information will be publicly available sometime this season.”
Measuring and Monitoring the Storm
Once it’s determined a hurricane or tropical storm will likely strike somewhere in the U.S., and if it’s deemed safe and necessary, USGS field crews will deploy to the storm’s projected path along the coast 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 forecast models. It also helps relief efforts by FEMA and other federal, state and local agencies by pinpointing the areas hardest hit by storm-tide flooding.
Storm-tide sensor information can also help engineers design structures to withstand floods better and assess how well engineered dunes and wetlands reduce storm damage. It can help inform land-use practices and building codes which can lead to more resilient coastal communities.
USGS crews may also install rapid-deployment gauges at locations that are not monitored year-round with permanent streamgages but are at risk of flooding due to an approaching storm. These RDGs provide real-time information on water levels, precipitation, wind speed, humidity and barometric pressure to emergency managers tracking floodwaters.
RDGs can be quickly installed at critical locations to help augment the USGS’s nationwide real-time network of streamgages, about 8,500 of which transmit both streamflow and water level data, while another 1,700 streamgages transmit only water levels. The National Weather Service uses data from the streamgages that provide both water level and streamflow to develop flood forecasts. 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 flooding and plan emergency response; they also allow the public to monitor local rivers and stream levels in real time.
You can track current storm-tide sensor and RDG deployments and view deployments from 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.
Determining the Extent of Flooding
Once it is safe to do so after the storm has passed, USGS field crews usually travel to affected areas to make real-time streamflow measurements, verify the accuracy of streamgage readings and quickly repair or replace damaged or lost gauges. This work is vital to flood forecasting and informs decisions on how best to protect communities.
USGS crews often fan out across affected areas to document high water. They look for telltale lines of seeds, leaves, grass blades and other debris left behind on tree trunks, buildings, bridges and other structures as floodwaters recede. Once they find these high-water marks, they photograph them, take notes, and survey them to determine the depth and range of the flooding. This fieldwork is time-sensitive because high-water marks can be destroyed by weather and property owners’ cleanup efforts. FEMA uses high-water mark data and related information to steer relief to areas of greatest need in the days after a storm, and later, to update flood insurance maps.
USGS specialists can develop indirect measurements of water flow using high-water marks in places where flooding was not measured by an instrument. A computer model uses information about the stream’s shape, depth and vegetation to determine how much water flow it would take to create a flood that produced the high-water marks.
To analyze field data gathered 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 U.S. and its territories. These data are used for mapping flood inundation from storms, 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 supporting infrastructure repair and redevelopment after a storm.
The USGS 3D Elevation Program acquires the information nationwide and makes it available on The National Map.
Creating Maps and Apps for Hurricane Response
During a disaster like a hurricane, first responders often rely on the USGS National Geospatial Program, which collects, archives and shares digital records of the nation’s topography, natural landscape and human-made environment. The program’s Geospatial Information Response Team (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 digital maps or on printed maps that can provide a big-picture view of a storm’s impacts or a close-up of a specific community.
“In the 2020 hurricane season, the GIRT will continue to provide situational awareness of storms and the aftermath through the USGS Event Support Map,” said USGS physical scientist Lance Clampitt, the GIRT chairman. “We are also ready to support requests for hard copy U.S. topographic maps or base map information for search and rescue missions or response operations.”
Recovering and rebuilding
The work of repairing and rebuilding in the aftermath of previous hurricanes continues. Congress has funded Federal agencies for hurricane-related expenditures in parts of the Southeastern U.S. and Puerto Rico affected by recent hurricanes. The money allocated to USGS included funding to restore scientific infrastructure damaged in North Carolina by Hurricane Florence, in Florida by Hurricane Michael and in Puerto Rico by Hurricane Maria.
In the wake of Hurricane Maria, which triggered more than 70,000 landslides when it passed over Puerto Rico in 2017, the USGS worked with the University of Puerto Rico Mayagüez and the University of Colorado Boulder to publish a Landslide Guide for Residents of Puerto Rico, which is available in English and en Español. The project team is working with stakeholders in Puerto Rico to increase awareness of landslide hazards and to share strategies that can mitigate landslide risks.
USGS has recently acquired new high-resolution lidar imagery in many coastal areas. The images allow scientists to assess topographic changes caused by major storms such as beach and dune erosion, landslides, and damage to buildings and infrastructure. In areas of coastal Florida and Georgia affected by Hurricane Michael in 2018, new lidar images have been acquired and processed. The data will be used to update vegetation and wildfire fuels mapping in forested areas damaged by Hurricane Michael. This, in turn, will allow scientists to better understand how hurricanes can impact wildfire risks. The lidar datasets are publicly available on The National Map website or are in progress.
Hurricane Preparedness Resources
For more information please visit these websites:
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