Metropolitan areas in the United
States are growing at unprecedented
rates, creating extensive urban landscapes.
Many of the farmlands, wetlands,
forests, and deserts that formed
the America of 1900 have been transformed
during the past 100 years into
human settlements. Almost everyone
has seen these changes to their local
environment but without a clear
understanding of their impacts. It is
not until we study these landscapes
from a spatial perspective and the
time scale of decades that we can
begin to measure the changes that
have occurred and predict the impact
of changes to come.
The U.S. Geological Survey's (USGS)
Urban Dynamics Research (UDR)
program studies the landscape transformations
that result from the growth
of metropolitan regions over time.
Using sources such as historic maps,
aerial photographs, and Landsat satellite
data, USGS scientists first assemble
retrospective urban land use databases
that reflect several decades of
change. These databases are then used
to analyze the effects of urbanization
on the landscape, and to model urban
growth and land use change under
alternative growth scenarios.