Ground Freezing Effects on
Soil Erosion of Army Training Lands
Part 1: Initial Test Results
LAWRENCE W. GATTO
INTRODUCTION
cles through rootsoil bonds, 2) reducing rainfall
erosivity by intercepting free-falling raindrops
Soil erosion
and reducing the number and kinetic energy of
Soil is naturally eroded by water flowing
raindrop impacts onto the soil surface (Evans
down bare or partially vegetated hillslopes; this
1980), and 3) reducing overland flow velocities by
erosion is a function of the erodibility (detachabil-
increasing friction where plant stems protrude
ity) of soil particles and the transport power
into the flow (Prosser et al. 1995). Thus, any pro-
of flowing water (Table 1). Soil erodibility is a
cess that alters either the physical strength of a
soil or reduces its vegetative cover increases the
interlocking. The strength of these particle inter-
likelihood of water erosion of that soil.
actions depends on soil particle size and distribu-
tion, soil structure and structural stability, soil
Effects of Army maneuvers on
permeability, water content, organic matter con-
training land erosion
tent, and clay, mineral, and chemical constituents
The Army is responsible for over 18,500 square
(Lal and Elliot 1994). Crusts that often form on
miles (4.8 104 km2) of training lands that are
soil surfaces also increase the resistance of soil
principally used to ensure the military readiness
particles and aggregates to erosion.
of its units (Doe 1992). Trainers must maintain
In addition, vegetation cover significantly in-
realism during maneuvers, but the goals of readi-
fluences the amount of soil erosion at a location
ness and realism often conflict with environmen-
by 1) binding surface and near-surface soil parti-
Table 1. Factors that determine the severity of water erosion. (After Lal 1994.)
I. Climatic erosivity
1. Rainfall erosivity
A measure of the ability of rain to detach sediment particles and surpass the infiltration capacity of soil so that
overland flow begins.
Also called the Energy-Intensity (EI) parameter, a function of rainfall volume, raindrop impact, and peak intensity.
2. Runoff erosivity
A measure of the ability of flowing water to detach and transport sediment particles.
A function of runoff volume and peak flow.
II. Soil erodibility
A measure of the susceptibility of sediment particles to being detached and transported by rain and flowing water.
A function of soil texture, structure, permeability, organic matter content, chemical constituents, and clay
mineralogy.
III. Topography
Hillslope length, steepness, and shape influence overland flow velocities and turbulence, which partially deter-
mines the likelihood of rill formation.
IV. Land use
Disturbance to a soil surface influences the effectiveness of raindrop impacts in moving soil particles, soil infiltration
rates, and overland flow velocities and turbulence.
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