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Only the Barren Land category of Strip Mines, Quarries, and Gravel
Pits was observed in either study area. Undoubtedly, other barren land
did exist in Study Area II but it was too small in extent to be detected
as a distinct entity on the radar imagery. Surface mining activity was
readily apparent in the semi-arid and arid environments owing to its
size, configuration, and contrast with the landscape. In the more humid
sections of the Midwest and the Northeast such activity was more difficult
to detect. Operations were smaller in area and often concealed by the
surrounding trees, contributing to decreased visibility.
Map Comparisons
A final experiment was conducted in evaluating the effects of
environmental modulation on radar land use mapping potential. Small
scale thematic land use regions were delimited on the radar imagery and
compared with two of the most widely known and current land use maps of
the United States: 'Major Land Uses' (scale 1:7,500,000) by J. R.
Anderson (1970) and "Land Resource Regions and Major Land Resource Areas
of the United States" (scale 1:10,000,000) by M. E. Austin (1965). In
Study Area I it became quickly apparent that relationships could be made
only with difficulty. Although a few instances of compatibility were
evident, for the most part a great deal of subjectivity was requisite to
envision commonalities. This was a marked contrast to results obtained
in Study Area II.
In the Midwest and West a majority of land use regions created from
radar imagery corresponded to regions created by other methods. Eight
of the ten land use divisions compiled by Anderson and seven of eleven
divisions compiled by Austin were found to be similar to land use divi-
sions created from radar. Where differences occurred the radar land use
regions appeared to be a finer distinction in land use than that derived
by other methods. In these situations the radar regions could be termed
sub-regions of more generalized land use or land resource regions.
However, this similarity should not be considered an unqualified endorse-
ment of radar imagery. Instead, it is suggested that the imagery could
be used to revise existing thematic land use maps by delimiting borders
and extent of land use activities. Radar imagery should be employed in
combination with other data sources when they are available and/or
desirable.
The lack of consistency between study areas and diminished detect-
ability can be attributed to environmental modulation. The fragmented
and complex land use pattern extant in the Northeast, in combination with
dissected topography, extensive forest vegetation, and a more homogeneous
climate, produced an intricate but in many ways concealed landscape.
The Northeast simply did not contain sharp, distinct breaks in land use
practices compounded by the fact they were neither extensive in area nor
great in number of types. Consequently, while a rather accurate, if
somewhat general, delimitation of land use activity and pattern could
be generated employing radar imagery as a data base it was not possible
to replicate results obtained by more traditional methods; it was a
distinct entity.
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