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I believe floods are our toughest scenario.
It’s very difficult to predict how bad bad will be.
The timeliness of information is everything.
Floods are the deadliest, most frequent, and the most expensive natural disasters in the
United States and around the world.
We need the right information in the right time in order to make decisions that will
make a difference in saving lives or moving resources around.
We're trying to acquire any kind of information that would help us understand the size and
scope of a flood.
You know, the faster that we can get the information, the faster we can get it into the hands of
the ground teams, the first responders, as well as to the senior decision makers who
are allocating limited resources.
Data drives effective decisions.
NASA’S Earth-observing satellites provide information about the situation on the ground
that can only be obtained from the perspective of space.
Texas uses remote sensing and other information from sensor data that’s collected to support
first responder teams in the field.
The satellite data really helps the state in their emergency management for large-scale
disasters by showing the extent and magnitude of a large-scale disaster.
When a flood is beyond a state’s ability to respond, the governor asks the President
to declare a federal disaster.
The Federal Emergency Management Agency evaluates the scale and impact of the event.
So information that they would provide from the state is normally the number of homes
that are impacted, the number of businesses that are impacted, so we are asked to verify
that information within the first hours of an event.
The more quickly FEMA determines the scope of a flood, the more quickly the President
can declare a federal disaster and mobilize federal resources.
FEMA gathers information from sources including the National Weather Service, the U.S. Geological
Survey, the National Geospatial- Intelligence Agency, and the Civil Air Patrol.
In October, 2015, as torrential rainfall soaked the Carolinas, FEMA was contacted by NASA’s
Disasters Program.
The Disasters Program promotes the use of NASA Earth observations in disaster response
and mitigation.
NASA joined the community of federal agencies responding to floods in the United States.
During the major floods that followed, NASA scientists provided data and images from the
GPM, Suomi-NPP, Aqua, Terra, and EO-1 satellites.
They used the satellite data to measure and map the rate of rainfall, detect areas with
power outages, and predict soil moisture, a factor in flash flooding.
The high-resolution ASTER and Advanced Land Imager sensors mapped the extent of flood
inundation as the floods evolved.
NASA-supported scientists modeled the predicted extent of flooding and mapped the actual extent
for FEMA.
Because MODIS, ASTER, and similar sensors are optical, they can only collect data in
daylight and when clouds don’t obscure their view of Earth.
Generally in floods we have significant cloud coverage that lasts for days.
Synthetic Aperture Radar, or SAR, can scan the Earth’s surface at night and in all
weather conditions by transmitting a radar signal to the ground that reflects back to
the source.
Although NASA doesn’t currently have a SAR satellite, other space agencies do.
Those SAR satellites are orbiting around the Earth continuously, but they don't always
acquire data when they visit a specific place.
Dr. Yun and his team check whether any of the SAR satellites imaged the flood area before
the flood.
To map the flood extent, they need to compare “before and after” SAR images from the
same satellite.
Then we contact them and coordinate with the international space agencies so that they
can turn on their SAR satellite and image that area.
By comparing SAR images of an area before, during, and after a flood, Dr. Yun can use
the changes in the Earth’s surface to create a flood proxy map.
Blue means the open water due to the flooding, and the red means the flooded area but with
vegetation sticking above the water surface.
Dr. Yun and his group also produced flood proxy maps for the August 2016 flooding in
Louisiana.
We estimated that Louisiana would have about 27,000 damaged homes, but it was through the
acquisition of SAR data and other remotely sensed data that we were able to see that
that was a much larger impact than we had forecast.
That information helped FEMA managers decide to increase the amount of resources sent to
Louisiana.
In 2021, NASA will launch its own SAR satellite in collaboration with the Indian Space Research
Organization, ISRO.
The mission is called NISAR.
The data from the mission will be publicly available.
I think it's going to be extremely useful for flooding, storm surge analysis, earthquake
analysis, so I see that as a future asset that we'll leverage quite heavily.
NASA’s participation in the federal flood response helped form new connections and
partnerships within NASA and across agencies.
It’s just a great feeling to see another agency, another group of extremely smart people,
come together to help with the effort.
The Applied Sciences Disasters Program continues to work with partners in the U.S. and abroad
to make full use of NASA’s unique resources when natural disasters strike.
For more information on the NASA Earth Science Disasters Program, visit disasters.nasa.gov.
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