by John Weier - July 2, 1999 |
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Millions of people in the United States and
around the world have no
idea that they live on a floodplain. Worse yet, they probably will not
find out until its too late. Their ignorance does not stem from crooked
developers or shady land deals, but from a lack of cartography. Very few
extreme, one-hundred-year floods are mapped out as they occur. Since
these natural events are so rare and cover such a large area, people
lose track of which lands were flooded. Without the benefit of
historical records, residents build on ground that once was and may
again be underwater.
Geomorphologist
Bob Brakenridge and a team of scientists at Dartmouth
College are working to correct this situation. For the past four years
they have been searching the world with orbiting imaging satellites,
trying to spot extreme floods. When the members of the team identify a
fifty-year flood or a hundred-year flood, they obtain an image of the
inundated area with the satellites sensors. From these images the
scientists create floodplain maps, which they then catalog on a database
for everyone to use. The teams efforts have already helped hydrologists
and floodplain managers to better understand floods. In the future, the
techniques Brakenridge and his colleagues develop could allow people to
see extreme floods as they progress in real time.
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A worker from the Federal Emergency Management Agency (FEMA) inspects flood damage in Clear Lake, California. (Photograph by Andrea Booher and Greg Mathieson, FEMA Emergency Information and Media Affairs) | |
Advanced Very High Resolution Radiometer images before (left) and during (right) a flood in Northern Russian, near the Barents Sea. Ice flows formed during the unusually cold winter of 1997-98 and blocked the mouth of the Pechora River, flooding several towns. Scientists used the data to make a map of the flood. (Images by E. Anderson and R. Brakenridge, Dartmouth Flood Observatory) |
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