Color infrared imagery is used to determine the location of buggy routes and to quantify the extent of tracks in a selected area where the marsh is seriously dissected. The imagery is used to show successive stages of destruction. It is recommended that alternate routes be identified in the operating area to eliminate continuous use of the same route and facilitate faster revegetation

Doiron, L. N.

Whitehurst, C. A.

English

NASA Technical Reports Server

N 7 5- 1 5 1 2 7
THE USE OF COLOR INFRARED IMAGERY
FOR THE STUDY OF MARSH BUGGY TRACKS
by
Charles A. Whitehurst
Professor of Environmental Engineering
Division of Engineering Research
Louisiana State University
Baton Rouge, Louisiana
and
Linda N. Do iron"'
Research Assistant
I R E U S E O F C C L O F I N F R A R E D I K A G E B Y E C * I K
S T U D Y O F M f t F S H B U G G Y T R A C K S (Louis iana
U n i v . ) 13 p HC $ 3-2 5 CSCL CbH
N75-15127
Unclas
/43 06615
^Presently in Graduate School, Geography Department, UCLA, Los Angeles, California
https://ntrs.nasa.gov/search.jsp?R=19750007055 2020-03-23T01:28:24+00:00Z
THE USE OF COLOR INFRARED IMAGERY
FOR THE STUDY OF MARSH BUGGY TRACKS
by
Charles A. Whitehurst
Professor of Environmental Engineering
Division of Engineering Research
Louisiana State University
Baton Rouge, Louisiana
and
Linda N. Doiron*
Research Assistant
*Presently in Graduate School, Geography Department, UCLA, Los Angeles, California
ABSTRACT
Due to the repeated use of marsh buggy routes in south
Louisiana, marsh sediments and vegetation have been compacted.
The waterlogging of the vegetation causes death of the vegeta-
tion, thereby producing elongated water bodies. Revegetation of
these areas are possible, but it depends upon the number of times
the tracks have been used. The revegetation period usually varies
between two and ten years.
To facilitate a faster revegetation, alternate routes should
be used, thereby lessening the damage to the marsh area.
Key Words: Marsh buggy, routes, vegetation, waterlogging, water
bodies, revegetation, damage.
INTRODUCTION
Temporary and permanent damage of marshland environments due to
the use of marsh buggies is becoming a major problem in the Louisiana
coastal zone. The two kinds of buggies used, tracked and wheeled
vehicles, create similar effects by compacting the marsh sediments and
vegetation. Waterlogging of the vegetation causes death, leaving elon-
gated water bodies in the tracks. Where the routes are repetitiously
used, the compaction is increased, deepening the tracks and decreasing
the possibility of revegetation. Revegetation periods vary according
to the number of times the tracks have been used and range between two
and ten years (Davis, personal communication).
GENERAL DISCUSSION
Studies have indicated that the degree of compacting and subsidence
due to loads is dependent on the marsh type (Nichols, 1959b). Most
important is moisture content - the higher the moisture content, the less
load the marsh will support. In dry periods when there is little water
on the marsh, the strength of the upper two feet has been found to
increase (Nichols, 1959). The thickness of the upper portion consisting
of root material and water determines the amount of compaction that will
occur.
In this study, color infrared imagery was used to determine the
location of buggy routes and to quantify the extent of tracks in a
selected area where the marsh is seriously dissected. The imagery was
also used to show successive stages of destruction.
The National Aeronautics and Space Administration (NASA) provided
aircraft support for this project, as well as the majority of the flight
data, in the form of color infrared imagery, which was obtained on
May 14 and October 25, 1973. The May imagery was recorded with an
RC-8 camera which produced nine by nine inch transparencies at a
scale of 1:6,000. The detail on the imagery was sharp and excellent
\
for detecting the marsh buggie tracks and for measuring their length.
A Hasselblad camera was used to record the October imagery, producing
transparencies which had a format of 2 1/4 by 2 1/4 inch and a scale
of 1:11,500. This smaller scale was used for detecting the tracks,
however, distinguishing among numerous tracks is much more difficult.
One of the main advantages of using color infrared imagery for
detection of marsh buggy tracks is the strong delineation between land
and water. Water reflects very little infrared radiation, and if free
of particulate matter, appears dark on the imagery. Tracks which have
compacted enough to contain water show as dark blue or black against
the red return of vegetation. Differences in the returns based on
abundance also allows detection of marsh tracks where revegetation is
occurring.
Figure 1 is a map showing the general area where NASA coverage
was obtained. The imagery clearly shows that the areas adjacent to
the Southwest Canal to be highly dissected by buggy tracks. Vehicles
are usually transported to the vicinity of a survey site by water.
Spoil banks and marsh areas near the canals are used for parking and
a hose of operation. The Southwestern Louisiana Canal is oriented
NE-SW through a salt marsh environment dominated by Spartina alterni-
flora. Sediments along the canal are unconsolidated much soils con-
sisting of approximately 15% clay, 53% silt, and 32% sand and contain
an average of 20% organic material. During the summer months, the
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marsh is saturated and usually has several inches of standing water
on it. There is seldom any water covering it during the dryer winter
period.
From ground level, the tracks are most obvious during the winter
months when most of the vegetation is dead. In the summer when the
abundance of vegetation is at its peak, the tracks can be detected from
a distance since there appears to be swales across the tops of the
vegetation where the tracks exist. There is no problem in locating
tracks or swales on the IR imagery and only through the use of this
mechanism can the magnitude of marsh buggy use in South Louisiana be
determined.
The study area was divided into square plots along both sides of
the canal (Figure 2). Linear measurements were made of the tracks
shown on the imagery in each square. Because of the inability to deter-
mine the number of times the tracks had been used, the measurements
represent routes of buggies rather than total usage. It should be
remembered, however, that many of these routes are used continuously.
The data collected shows that there is only a limited area where
there is a total absence of buggy tracks. These areas are in plots
47-50, and 52, which are located on the far western side of the canal.
The extent of buggy use in the remainder of the plots ranged between
4 and 78 miles of track routes per plot. The total area sampled was
6.11 square miles and contains over 1500 miles of track routes.
Several stages of destruction can be detected on the imagery. In
the initial stages, vegetation is matted and dead but compaction is not
great enough for water to accumulate in the tracks. The dead vegetation
is indicated by a whitish color on the imagery contrasting with the dark
red return of the live vegetation (Figure 3).
With continued use, the sediments and vegetation are further com-
pacted and saturation and waterlogging are more evident. Increased
moisture appears as dark tones of blue or black on the imagery making
the tracks highly distinguishable (Figure 4).
Abandoned tracks will revegetate with time. Field data showed
that revegetation is by the same species of plants. Due to the fact
the vegetation is less abundant, the tracks are detectable on the
imagery as a light pink to red color (Figure 5).
The most advanced stage of destruction results from a combination
of subsidence and continued use of the tracks. Water areas increase,
and there is less chance of revegetation (Figure 6).
CONCLUSION AND RECOMMENDATION
Color infrared imagery makes it possible to locate those areas
which are most seriously damaged by marsh buggy tracks.
With a minimum effort in the field, considerable information re-
garding extent of use, stage of revegetation or deterioration, water
enroachment, etc., can be obtained. This would be practically impos-
sible to accomplish at ground level. The optimum use of buggies, or .
any other trackek vehicle, in marsh regions can be enhanced through
proper application of aerial imagery.
If the use of tracked vehicles is to be continued, we recommend
that alternate routes be defined in the operating area. This would
eliminate, to a large extent, continuous use of the same route and
would allow faster revegetation.
Figure 3 Initial stage of destruction where vegetation
is matted
Figure 4 Continued use increases compaction and tracks
become elongated water bodies
OR8IWAL
OF
IS
Figure 5 Revegetation of abandoned tracks
Figure 6 Advanced stage of destruction
REFERENCES
Davis, Donald W., 1974, Nichols State University, personal communi-
cation.
Nichols, L. G., 1959a, Geology of the Rockefeller Wildlife Refuge and
Game Preserve, Cameron and Vermillion Parishes, La.: Tech. Report
of the La. Wildlife and Fisheries Comm., 37 p.
Nichols, L. G., 1959b, Rockefeller Refuge Levee Study: Tech. Report of
the La. Wildlife and Fisheries Comm., 17 p.
10


The use of color infrared imagery for the study of marsh buggy tracks

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