As Hurricane Season Opens, USGS Is Ready
When a Hurricane Approaches, USGS is Ready
Scientists work in the field before, during and after landfall to improve forecasting and recovery.
There’s a good chance the 2017 hurricane season will be busier than normal, with National Weather Service forecasters predicting as many as 11 to 17 named storms and two to four major hurricanes. But this year as in the past, whenever a major hurricane is forecast to hit the nation’s Atlantic or Gulf Coast, U.S. Geological Survey scientists are ready to go well before the red-and-black hurricane warning flags unfurl. Starting about three days before a major storm’s predicted landfall, 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, and profoundly alter landscapes. The USGS has experts in these hazards, state-of-the-science computer models for forecasting them, and sophisticated equipment for monitoring actual flood and tide conditions.
Throughout the hurricane season the USGS Coastal Storm Response Team, made up of managers and scientists, confers with the National Hurricane Center and other federal agencies. When forecasters think a hurricane is likely to make landfall on the U.S. mainland, the storm team confers every day, says hydrologist Athena Clark, the USGS storm team leader.
Installing Sensors That Ride Out Storm Waves, Then Measure Them
The team decides the timing and extent of USGS’ storm response based on the storm’s forecast intensity and track, says Clark. If the storm is a Category 3 (with sustained winds of 111 miles per hour) or greater, or if especially vulnerable communities or ecosystems lie in its forecast path, USGS crews will be deployed in advance. Among the early decisions the team makes: when and where to position the special storm-tide sensors that can measure the height, extent and timing of the storm tide that happens when the hurricane makes landfall?
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 models.
As Storm Rains Sweep Inland, USGS Tracks Flood Effects
Hurricane rains can cause flooding far from the coast. To track inland flooding, the USGS gathers data from its existing network of streamgages, which measure water levels, streamflow and rainfall at more than 8,100 sites across the country. Data from the streamgage network is used by the National Weather Service to develop flood forecasts, by the U.S. Army Corps of Engineers to make flood control decisions, and by local agencies in emergency response. In addition, the USGS quickly installs specially-designed rapid deployment gauges in areas where flooding is likely, but no permanent stations exist.
When flooding occurs, USGS field crews make real-time streamflow measurements to verify the streamgages’ readings. The crews also quickly replace storm-damaged or lost gauges. And to further document the extent and depth of flooding, the experts in the field document high water marks – the telltale lines of seeds, leaves, silt and other debris left behind on buildings, bridges, and trees after floodwaters recede.
During and right after hurricane flooding, these records help the Federal Emergency Management Agency target emergency relief to the hardest-hit areas. Later, the data help insurers and property owners document damage, and provide real world information to validate and improve computer-modeled flood forecasts.
You can track storm-surge sensor deployment and see streamgage readings in real time at the USGS Flood Viewer.
Predicting How the Storm Will Shift Protective Dunes
This year, for the first time, scientists at the USGS’ St. Petersburg Coastal and Marine Science Center are using unmanned aerial systems – commonly known as drones – to study hurricane impacts. It is part of an extensive effort to forecast and document the impact of hurricanes and other weather events on Gulf and Atlantic shorelines.
Research scientists at the center have developed a coastal change hazard forecast model, a sophisticated computer program that provides detailed predictions of a hurricane’s likely effects on sand dunes and other coastal features. The forecasts cover the Atlantic and Gulf coast regions where storm effects are expected, at one-kilometer intervals. They predict where protective sand dunes are likely to be eroded at their bases or overtopped by storm waves, and where coastal areas 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.
When a major hurricane strikes the U.S. coast, the team collects thousands of aerial photographs to document coastal changes. This year the scientists plan to deploy the new drones – quadcopters that resemble oversized video game controllers – before and after storm strikes. The drones collect high-resolution images before and after the storm. Scientists will use a technology called “structure from motion” to convert information from the images into dune elevations, says research oceanographer Joseph Long, a member of the USGS’ coastal change hazards team. The image processing algorithms will allow the team to document how sand dunes changed during the storm and improve the models’ future coastal erosion forecasts.
This season the team is also testing and refining new forecasts of coastal water levels, using a model developed with the National Weather Service. These experimental forecasts will predict how far up the beach waves will push seawater, showing hour-by-hour estimates of wave runup, updated several times a day. This work uses stationary video cameras installed in Tampa Bay and on North Carolina’s Outer Banks.
Maps and Apps That Show the Big Picture
With information pouring in, often while USGS staffers are still coping with the storm’s consequences, managers need a way to quickly shape the data into a clear picture of the situation on the ground. The USGS’ Geospatial Information Response Team (GIRT), an ad hoc group of scientists with expertise in many different facets of mapping, handles that vital task during hurricanes and other natural disasters.
Using a web app designed to help storm team members, scientists and others working on storm response, the GIRT 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, said USGS physical scientist Lance Clampitt, the GIRT chairman.
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. Finally, the GIRT provides the geographical information that USGS staffers and first responders need, including the USGS’ legendary topographical maps.