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Review
of legacy data
Concepts:
NLCD
Maine Gap
Maine_combo
CCAP
Gulf of Maine
We
include on the DVD five datasets which historically have been widely
used in Maine for landcover analysis. These are NOT part of the
NLCD 2001 or MELCD 2004 projects, but in the interest of providing a
thorough source for Maine landcover, they are included. All of
these are available to DEP users (in
data_layers\landuse_landcover). Some of them are available to
state agency users on the ArcSDE server, and all of them are on the
MELCD 2004 DVD. They all are based on LandSat imagery alone, with
30-meter pixel resolution, and imagery dates from 1986 to 1997.
Accuracy for products of this era is far below what is achieved with
NLCD 2001 and MELCD 2004.
National Landcover Dataset (NLCD)
This is the original NLCD project based on LandSat data scenes from
1988-1993 and contains 18 classes. It was the first project to
map landcover consistently for the entire country at a 30-meter
resolution. Metadata
Maine Gap
The Maine Gap Analysis Project mapped landcover with the purpose of
modeling vertebrate fauna distributions. Although a national
program within USGS, each state's project was undertaken independently
with few exceptions. Maine's classification reflects the strong
presence of managed forestlands in the landscape. LandSat scenes
from 1991-1993 were used to create a dataset with 38 classes and an
overall accuracy of 52% based on 41,120 samples from aerial videography
(Hepinstall et al. 1999, p. 40). Metadata
Maine_combo
After much use, it was clear to some users at Maine DEP that NLCD had
certain classes depicted better than Gap, and that Gap had others that
were better than NLCD. These users were principally interested in
estimating imperviousness from landcover class - so this perspective
may not be shared by other users. The two products were merged
based on a set of rules regarding which class had priority where pixels
disagreed. This layer became widely used among watershed
scientists in the state. Metadata
CCAP
The original NOAA Coastal Change Assessment Program (CCAP) was mapped
on a scene-by-scene basis, so Maine has 3 different mapped areas.
For each, a circa-1986 and a circa-1992 landcover dataset was created
with 15 classes, along with change-detection data. Metadata
Gulf of Maine Landcover
US Fish and Wildlife developed this dataset which is an amalgamation of
basically all the available landcover data for the Gulf of Maine basin
as of 1997, including NLCD, Gap, CCAP, and wetlands data. Metadata
Cited: Hepinstall, J.A., Sader, S.A,
Krohn, W.B., Boone, R.B., and R.I. Bartlett. Development and
testing of a vegetation and land cover map of Maine. Maine
Agricultural and Forest Experiment Station Technical Publication 173,
104 pp.
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