same period (Table 7). During the late August to
The inherent complexity of this dynamic en-
early September flooding cycle, 36 mm of new
vironment makes it extremely difficult to pre-
material was deposited, while 26 mm of materi-
dict what effects potential remedial measures
al had been resuspended and redeposited. Dur-
for WP contamination will have on the physical
ing the winter 199293 period, resuspension sedi-
system and conversely what short- and long-
mentation ranged from 2 to 15 mm, or similar to
term effects the physical system will have on the
that of the summer 1993 amounts.
effectiveness and success of proposed remedies.
Within gullies, deposition occurs mainly along
Understanding both the system's response and
the lateral slopes away from the channel thalweg.
the effects of remedial measures are critical to
Depending on the depositional process, rates
developing cleanup strategies. Further analysis
could range as high as 10 to 30 cm for the sum-
of the processes and factors determining tidal
mer period, with several or more centimeters
flat hydrology and sedimentology are required
being deposited during a single flood and ebb
to predict the system's response to a particular
cycle. These rates primarily reflect adjustments in
remedial technology. The remediation process
the gully cross section, rather than deposition
may be enhanced or hindered by the physical
from tidal flood waters. Mass movements of
system. Questions regarding remediation will
slope material account for the majority of the
be addressed in our continuing investigations of
sediment deposited on lateral slopes. Sedimen-
the physical system dynamics of Eagle River
tation rates are therefore highly variable from
Flats.
place to place. Note that the 199293 winter and
1993 summer gully measurements are not
LITERATURE CITED
directly comparable to the 1992 summer mea-
surements because most of the 1992 stakes within
Andrew, J. and G. Cooper (1993) Sedimentation
the center of the gully were lost to erosion or
in a river dominated estuary. Sedimentology, 40:
burial.
9791017.
Allen, J.R.L. (1982) Sedimentary structures:
Their character and physical basis. In Develop-
SYSTEM DYNAMICS AND REMEDIATION
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Eagle River Flats is a dynamic estuarine salt
Elsevier.
marsh that is actively undergoing progressive
Allen, J.R.L. (1990a) Constraints on measure-
and significant changes in the physical environ-
ments of sea-level movements from salt marsh
ment. These changes result from the interaction
accretion rates. Journal of the Geological Society,
of multiple physical processes with various fac-
London, 147: 57.
tors that include external forces such as a high
Allen, J.R.L. (1990b) Salt marsh growth and
tidal range, a glacial river, two relatively large
stratification: A numerical model with special
sediment sources and a cold climate. The location
reference to Severn Estuary, southwest Britain.
Marine Geology, 95: 7796.
of ERF within an active earthquake zone adds
Allen, J.R.L. (1992) Large-scale textural patterns
further to the complexity and the potential for fu-
and sedimentary processes on tidal salt marshes
ture rapid, but probably unpredictable, physical
in Severn Estuary, southwest Britain. Sediment-
changes. If the area subsides, or conversely up-
ary Geology, 81: 299318.
lifts, because of an earthquake, major changes in
Allen, J.R.L. and J.E. Rae (1988) Vertical salt
the hydrology and terrain can be expected. While
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pond areas may increase because of subsidence,
Severn Estuary, southwest Britain. Marine Geol-
as happened in 1964, the drainage system and
ogy, 83: 225235.
river channel may respond with increases in
Bartsch-Winkler, S. and A.T. Ovenshine (1984)
rates of erosion or sedimentation because the
Macrotidal subarctic environment of Turnagain
drainageways will be out of equilibrium with the
and Knik Arms, Upper Cook Inlet, Alaska: Sedi-
altered physical environment. In addition,
mentology of the intertidal zone. Journal of Sedi-
ground explosions and cratering during the use
mentary Petrology, 54: 12211238.
of ERF as a military firing range since the early
Bloom, A.L. (1984) Peat accumulation and com-
1940s have caused physical changes to the ter-
paction in a Connecticut coastal marsh. Journal
rain, hydrology and surface drainage. Craters,
of Sedimentary Petrology, 34: 599603.
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Boon, J.D. (1975) Tidal discharge asymmetry in a
drainages and enhanced gully expansion.
34
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