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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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