Satellite maps offer sprawl insight
- By Brian Robinson
- Jun 05, 2001
Mid-Atlantic Regional Earth Science Applications Center
State agencies and local government planners now have ready access to inexpensive
satellite-based maps for monitoring water quality, as the result of a NASA-sponsored
program that provides detailed and accurate maps of impervious surfaces
such as buildings and paved areas.
Maps of such surfaces show planners where large storm water runoffs
can occur, and therefore, where they can expect major erosion and large
levels of soil and chemical discharge into rivers, streams and ground water.
Urban sprawl significantly increases these problems.
The trouble, according to Andrew Smith, a faculty research assistant
who is developing the maps at the University of Maryland's Mid-Atlantic
Regional Earth Science Applications Center (RESAC), is that local governments
have been able to generate such detailed maps only by using aerial photography,
a process that can cost tens of thousands of dollars. That cost makes the
process too expensive for many governments.
"By contrast, satellite maps can be provided much more regularly, since
the satellites are always up there, and they cost only several hundred dollars,"
Smith said. "Ancillary data is needed, which can boost the cost some, but
even so it's far less than what aerial photography costs."
The Landsat 7 images that are used now are lower-resolution maps than
those produced from aerial photography, Smith said, but he expects that
images from satellites that will be launched over the next few years will
produce maps accurate to four-meter and, eventually, one-meter resolutions.
The RESAC team already has provided maps to the Chesapeake Bay from
Space project, the Maryland departments of Planning and Natural Resources
and the Montgomery County Department of Environmental Protection, among
others. It is working with planning departments to see how to add the data
from the maps into future urban planning models.
Smith said the technique should be made available to governments across
the rest of the country in the next several years. He also is hopeful that
it can be applied to other natural features that might be affected by sprawl,
such as tree and plant cover.
Robinson is a freelance journalist based in Portland, Ore.
Brian Robinson is a freelance writer based in Portland, Ore.