HANCOCK COUNTY, Miss. — Next to fire, floods are the most common
and widespread of all
natural disasters. As communities around the nation prepare for this
year’s flood season, Earth
scientists at NASA’s Stennis Space Center are at work on several
projects to help communities
better understand flood risk.

Flood insurance — not typically included in traditional
homeowner’s insurance — is one
essential element of flood-risk planning. Communities must meet
Federal Emergency Management
Agency (FEMA)-approved flood mapping requirements to be eligible for
flood insurance. Flood
insurance premiums are based, in part, on flood-risk maps, which
contain detailed information on a
community’s risk of flood. These maps are prepared using remotely
sensed data—data about the
Earth collected from distant vantage points.

One type of remote sensing system called light intensity detection and
ranging (LIDAR)
collects data by sending and receiving pulses of light. Scientists
interpret LIDAR data to detect tiny
changes in the Earth’s topography and thus predict exactly where
floodwaters will go and how they
will behave. The accuracy of LIDAR data depends on the number of
pulses that are sent and
received perxzer of coverage. However, the more accurate the data,
the more expensive it is for
communities to acquire. The optimal pulse rates and coverage for LIDAR
data for flood mapping is
not yet known.

To get the best flood-risk mapping results for their money,
communities need technical
requirements guidelines. This is where NASA’s Earth scientists can

Current and future NASA research projects in North Carolina, Texas and
Mexico will help
determine appropriate LIDAR accuracy in flood-risk mapping by
examining optimum light-pulse
rates and the costs associated with those levels of accuracy. These
data will help FEMA update their
minimum LIDAR accuracy requirements and assist communities considering
flood-risk mapping.

"Qualifying results is critical for the most efficient use of LIDAR in
flood mapping," said
Dr. Bruce Davis, NASA’s acting chief of engineering for the Earth
Science Applications
Directorate. "This project is the first one of its type and has the
potential to help FEMA set flood
mapping standards and save communities money in flood risk mapping and
insurance costs."

"As a research and development agency, NASA has a fundamental
understanding of how
remote sensing works," said Davis. Since NASA does not provide
flood-risk mapping services to
communities, it can remain objective in its technical recommendations
for mapping requirements.

Davis, who hopes to organize a workshop in the early summer for flood
mapping experts,
notes that continued applied research in this area is critical for
finding the balance between flood
mapping accuracy and cost savings. "NASA’s flood mapping projects are
a first look at optimal
LIDAR requirements," he said. "Much more work is needed in order to
apply the best information
to the most critical questions about flood mapping."