Introduction
Clearly,
change, including
in land cover and
land use, is a constant.
Humans have long
altered the land
by clearing forests,
farming, and building
settlements. Due
to advances in civilization,
human-induced changes
now occur much faster,
and in many ways
more dramatically
than in the past.
It is increasingly
apparent that these
rapid transformations
can have profound
social and environmental
implications. This
can be seen in the
Twin Cities of Minnesota,
a 7,700 km2 seven-county
region home to roughly
2.8 million people.
Its population is
forecast to top
3.5 million in 2020,
building on a trend
of the region being
one of the fastest-growing
metropolitan areas
in the nation.
A
New Approach
We
integrate several
different approaches
to describe and
understand the processes
of urbanization
and land use change
in Minnesota 's
metropolitan and
rural areas. We
start by creating
maps of the changing
landscape based
on imagery taken
from satellites
orbiting the planet,
an approach that
offers an effective
method for inventory,
monitoring, and
analysis of land,
vegetation, and
water resources.
This
new approach offers
several advantages:
-
Land
cover and impervious
maps and statistics
for any location
(i.e., city,
county,
watershed).
-
Large
area coverage.
Landsat satellite
images cover
over
11,000 square
miles
and multi-county
areas, so the
same
image can be
used
to map different
locations.
-
Landsat
TM imagery has
been acquired
since
1984 so it is
possible
to evaluate changes
in land use and
imperviousness
over time.
-
A
digital format
compatible with
geographic information
systems.
-
Time
and cost savings
due to digital
classification
methods
being used instead
of manual interpretation.
Land
Cover and Imperviousness
We
are interested
in two particular
kinds of information
about Minnesota - the
kind of land cover
found in a given
location (e.g.,
urban, agricultural,
or forests) and
the percentage
of impervious
surfaces,
those like roads
or parking lots
that do not allow
water to penetrate
into the underlying
soil. We also
combine
these maps of
land
cover and impervious
surfaces with
other
data - such
as census figures,
political jurisdictions,
or physical characteristics
of the land - in
a Geographic
Information
System, a computer
system used to
manipulate
and analyze
spatial
data. In a related
project (see water.umn.edu)
we are using
the Landsat
data to monitor
lake clarity,
an important
indicator of
water quality.
Teaming
up to monitor
change
With
the advances in
mapping from satellite
imagery we are
able to create a
brand new resource - statewide
maps that can track
the whole picture
of urban growth
over time. What
does it show us?
That the key is
where and how fast
these changes are
occurring. Rapid
change (we have
seen an increase
almost doubling
the amount of impervious
surfaces statewide
in 10 years) can
come at a cost.
Looking at this
change has teamed
researchers from
the University
of Minnesota 's
Remote Sensing and
Geographical Analysis
Laboratory with
scientists and planners
from the Minnesota
Pollution Control
Agency and uses
this website to
provide the results
of new impervious
surface and land
use change monitoring
techniques to the
public in the form
of maps and statistics.
We hope the results
will be helpful
to you in your
local units and
decisions.
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