Laboratory studies will include large- and
resistance to hydraulic forces and determine run-
small-scale experiments carried out in the Frost
off formation rates and volumes (Kirkby 1980,
Effects Research Facility (FERF) at CRREL and
Gerits et al. 1990). Papendick and Saxton (1990) re-
small-scale experiments in coldrooms. Field
ported that research on frozen soil effects remains
research will be done in three hydro-climatic
a high priority. Cooley (1990) described the impor-
regions: the cool, semi-arid zone of south-central
tance of incorporating the effects of FT on soil
Washington at the Army's Yakima Training Center
compaction and strength, runoff, and erosion into
(YTC), the cold, humid area of upper New Eng-
soil erosion models. In spite of the accelerated ero-
land at CRREL or Ethan Allen Firing Range
sion that often results from Army maneuvers, past
(EAFR), Vermont, and the cold, dry climate of the
research has not determined the significance of FT
upper midwest, possibly at Camp Ripley, Minne-
in alleviating vehicular compaction, in reestab-
sota, or Fort McCoy, Wisconsin. The studies at YTC
lishing soil infiltration, in changing rut geometry,
and EAFR are currently underway.
and in determining sediment-transport capacity
This research will extend existing knowledge of
on training lands.
soil erosion mechanics, developed for the tradi-
Available research results conflict regarding the
tionally agricultural and rangeland settings, to
efficacy of FT in reducing vehicular compaction,
military training lands where soil frost forms. It
do not define the basic soilFT processes involved,
will provide information to terrain modelers to
and are absent regarding FT effects on vehicular
help improve their simulations of seasonally
ruts. The effects of FT on natural rills has been in-
dynamic soil processes that significantly influence
vestigated at a preliminary level. And we know
terrain evolution and hillslope soil processes. The
that snow cover can retard soil thaw and absorb
research results may eventually be used to modify
raindrop impact energy, but we lack details on how
the Revised Universal Soil Loss Equation (RUSLE)
snow affects soil particle detachment on the soil sur-
and WEPP soil erosion models to better simulate
face and affects soil creep along rills and ruts.
the effects of winter processes and conditions on
Laboratory and field experiments will be con-
runoff erosivity and soil erodibility, information
ducted to
that is now unavailable to Army land managers.
Measure FT-induced changes in shear
strength, penetration resistance, infiltration
rates, and surface geometry and roughness of
OBJECTIVES OF THE INITIAL TESTS
compacted and rutted soils for different FT
The objectives in these tests were 1) to see if I
regimes, compaction loads, and soil type and
could achieve the freeze rates in the soil bin locat-
water content.
ed in the FERF that would allow me to do my
Determine if compaction and ruts from
planned experiments, 2) to determine if the soil in
tracked and wheeled vehicles are affected
the bin would freeze and thaw in a natural fashion
differently by soil FT.
and, thus, reasonably simulate field conditions, 3)
Determine differences in the cross-sectional
to evaluate the operation and adequacy of the in-
shapes of rills and ruts caused by FT-induced
struments to be used in future experiments with
soil creep.
multiple bins, and 4) to measure cross-sectional
Evaluate how and to what degree soil FT
changes in a simulated, rectangular rill.
rates and soil water contents affect soil shear
strength and penetration resistance (soil
erodibility) of different soil types.
APPROACH
Use rainfall simulators to determine soil
Bin construction
erodibility with various antecedent soil
The first bin was constructed with two layers of
water conditions and soil types, and rainfall
pressure-treated, 3/4-in. (1.9-cm) plywood, rein-
erosivity before frost and after thaw on dif-
forced with pressure-treated, 2- 6-in. (5- 15-cm)
ferent slopes.
boards and insulated with one layer of 2-in. (5-cm)
Determine if snow cover alters the tempera-
polystyrene foam board on the sides and bottom
ture gradient in the soil sufficiently to reduce
(Fig. 8a). The inside of the bin was lined with an im-
the amount of water drawn to a soil freezing
permeable membrane (Fig. 8b) that was trimmed
zone.
and tacked to the interior walls. The bin in final posi-
Evaluate the effects of snow cover on the
tion for these first tests was horizontal along its long
amount of thaw creep along rills and ruts.
axis but sloped from its east side to its west approx-
Investigate soil particle detachment under
imately 0.5 in. in 4 ft (1.3 cm in 1.2 m). The bin is a
snow.
8
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