USGS Prepares for Hurricane Harvey
Scientists Ready to Track Storm Surge, Coastal Change and Flooding
As Hurricane Harvey moves toward the Texas coast, U.S. Geological Survey experts on storm-related hazards are taking action, along with other federal agencies, to help minimize potential risks to lives and property.
Before, during, and after any hurricane or tropical storm affects the United States, the USGS is involved in measuring the height and intensity of coastal storm surge and water levels of inland rivers and streams to provide critical information used to forecast floods. Using state-of-the-art modeling, the USGS is also involved in forecasting coastal change caused by waves and storm surge, assessing the likelihood of beach erosion, overwash or inundation.
Storm surge, large waves, coastal erosion, and inland flooding are among the most dangerous natural hazards unleashed by hurricanes. These have the capacity to destroy homes and businesses, wipe out roads, bridges, water and sewer systems, and profoundly alter landscapes. The USGS has experts on these hazards, computer models for forecasting them, and sophisticated equipment for monitoring actual flood and tide conditions.
The USGS has been closely monitoring the approaching hurricane in consultation with the National Hurricane Center and other agencies. On August 24, five crews from the USGS Texas Water Science Center were deployed to install scientific instruments in advance of the storm. Some of the equipment will measure the height and intensity of the storm surge while other instruments, such as streamgages, will monitor real-time water levels of inland rivers and streams. The field crews will gather scientific data from the instruments immediately after the storm has passed, which will provide critical information needed for accurate flood forecasting.
USGS researchers are also forecasting the amount of coastal change projected to result from the storm surge, using advanced modeling to assess the likelihood of beach erosion, overwash or inundation at the local level and along the entire Texas coast.
Prepared to Capture Storm Surge Measurements
Storm surges are increases in ocean water levels generated at sea by extreme storms and can have devastating coastal impacts. Scientists at the USGS and elsewhere want to better understand storm surges so that 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.
In preparation for Hurricane Harvey, the USGS installed around 15 storm-tide sensors along the coastline between San Luis Pass and Corpus Christi. The sensors are housed in steel pipes a few inches wide and about a foot long, and installed on bridges, piers and other structures that have a good chance of surviving a hurricane’s storm surge.
Streamgaging Network at the Ready
One significant hazard a major storm like Hurricane Harvey can create is inland flooding caused by heavy rainfall. USGS hydrologists are currently on alert in Texas and Louisiana preparing to track this threat.
The USGS Streamgaging Network operates sensors that record water levels and other key pieces of information on inland rivers and streams throughout the nation. With the support of local, state, and federal agencies, the USGS uses this nationwide network to provide real-time data to National Weather Service, Federal Emergency Management Agency, U.S. Army Corps of Engineers, and others.
USGS field crews installed two additional rapid deployment gauges in the Galveston Bay area along critical roadways to provide real-time information to forecast floods and coordinate flood-response activities in the affected areas. Rapidly deployable streamgages can be installed quickly and temporarily in areas to provide emergency managers with additional information needed to help protect public safety.
The public can access current conditions and critical flood information throughout Texas by using the USGS Texas “Water On-the-Go”. The mobile-friendly website/app will allow users to quickly locate USGS gauges in Texas that measure streamflow, stream height, rainfall or lake levels so that users can get up-to-date information on water conditions near where they are located. In addition, the Texas Water Dashboard presents USGS real-time stream, lake and reservoir, precipitation and groundwater data for more than 750 USGS real-time stream, lake, reservoir, precipitation, and groundwater stations in Texas.
Immediately after the worst of the storm has passed, hydrologists will check inland streamgages to verify high river and stream flows and peak water levels, and measure high-water marks left by floodwaters on buildings, bridges and trees. In the days after the storm, this information helps emergency managers and insurers direct resources to the hardest hit areas. The crews will also calibrate and repair streamgages damaged by the storm to ensure they continue providing valuable information in the aftermath of the storm.
Streamgage information is routinely used for a variety of non-emergency purposes, such as tracking and managing water supplies, monitoring floods and droughts, designing roads and bridges, and planning recreational activities on rivers and streams. In extreme weather, these data help inform decision makers as they issue flood and evacuation warnings, coordinate emergency responses to communities, and operate flood-control reservoirs. During a storm’s landfall, the network helps capture the depth and duration of storm-surge, the time of its arrival, and its retreat.
Tracking Coastal Changes
USGS scientists are using state-of-the art models to give emergency managers and local residents as accurate a picture as possible of what coastal changes Harvey is expected to produce.
Research scientists at the USGS’ St. Petersburg Coastal and Marine Science Center have developed the USGS Coastal Change Forecast Model, a sophisticated computer program that provides detailed predictions of a hurricane’s likely effects on sand dunes and other coastal features. The model uses the National Hurricane Center’s storm surge predictions and the National Oceanic and Atmospheric Administration’s wave forecast models as its starting point, and incorporates detailed geological information about beach slopes and dune heights along the entire coast.
The model can predict, at one-kilometer intervals, where protective sand dunes are likely to be eroded at their bases or overtopped by storm waves, and which coastal areas could be inundated by seawater. The information 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 Hurricane Harvey coastal change forecasts began August 23 at 1:00 p.m. Central time, more than 48 hours before the storm’s expected landfall, and is updated based on the latest forecasts from the National Hurricane Center. As of Friday morning, the USGS Coastal Change Forecast model is predicting that 94 percent of Texas’s 367 miles of coastline will undergo some level of beach erosion from the storm surge and large waves Hurricane Harvey will produce.
The Coastal Change Forecast model is also projecting that 47 percent of Texas’s coastline will experience a more severe level of erosion hazard, known as dune overwash, particularly north of Corpus Christi up to the Galveston area. As waves and surge reach higher than the top of a dune, overwash occurs, often transporting large amounts of sand across coastal environments and roadways, depositing sand inland and causing significant changes to the landscape and possibly impeding transportation routes.
Inundation is the most severe level of coastal damage from a storm and occurs when beaches and dunes are completely and continuously submerged by surge. Currently, 14 percent of Texas’s coastline is projected to experience inundation in areas north of Corpus Christi to the Galveston area. The forecasts are available to the public at the USGS Coastal Change Hazards Portal.
As with past storms, the scientists will also compare before and after photos of the coastline to study Hurricane Harvey’s impacts on the dune systems that help protect coastal communities and natural ecosystems from flooding and erosion.
More Resources to Help Prepare
As USGS continues to take all appropriate preparedness and response actions as Hurricane Harvey approaches the Texas coast, people in the path of the dangerous storm should stay-tuned to local announcements addressing evacuations or other safety issues. Information on how to prepare for a hurricane is available at www.ready.gov or www.listo.gov.
Hurricane Harvey Resources: