TM 5-830-3/AFM 88-17, Chap. 3
APPENDIX B
CONTROL OF WINDBORNE SAND
SECTION I
DESCRIPTION, DEFINITIONS, FORMATION,
AND-CONTROL OF DUNES
B-1.
Introduction
a. Sand sheets. These sheets occur in a generally
flat, barren area with a predominant wind direction. They
Many factors, including low rainfall, high evaporation,
present no control problems because the sand does not
sparse vegetation, and seasonal winds, contribute to
accumulate.
rock weathering and sand, movement. Methods of
controlling sand movement have met with varying
b. Fixed sand dunes. These dunes result from the
degrees of success. This appendix summarizes the
accumulation of sand particles adjacent to fixed
latest available information on windborne sand control
obstructions such as hills, cliffs, shrubs, and buildings.
and lists recommended methods of sand movement
Fixed sand dunes may range in size from an
stoppage and diversion.
Marine and river sand
accumulation around small shrubbery to sand shadows
movement control are not discussed herein.
more than 50 feet deep. Because the fixed sand dune is
immobile, it normally does not present a control problem.
B-2.
Wind, wind direction, crosswind
Figure B-1 -shows the more common types of fixed sand
dune formations.
Wind is defined as any natural movement of air, whether
of high or low velocity, or great or little force. Most
c. Moving sand dunes. This type of sand mass
regions have a predominant wind direction-some section
exists independent of fixed surface features and may
of the compass from which the wind blows most often
move from place to place maintaining its initial form.
and with the greatest velocity. Crosswinds are winds
Moving sand dunes are common .in vast areas of sand
directed at some angle to the predominant wind
with little or no vegetation.
The control methods
direction.
described below are applicable for this type of dune.
With relation to predominant winds, moving sand dunes
B-3.
Forms of dunes
are classified either as longitudinal or transverse (fig B-
2). Longitudinal dunes are distinct ridges elongated in
A dune is defined as a mound or ridge of windblown
the direction of the predominant wind (fig B-2a). A
material, usually sand, formed in arid regions. Local
combination of predominant and cross winds will
conditions under which dunes are developed vary widely,
produce a regular succession of of dunes (fig B-2b).
and, consequently, there is a broad range in their shape
Transverse; dunes are formed by wind of steady
and size.
The shape may, assume almost any
direction blowing across an extensive source of loose
configuration, and the size may vary from an insignificant
sand, such as a sandy beach, and building ridges
lone sand pebble to mounds higher than 100 feet. Some
transverse to the-wind direction. Low-velocity winds form
coastal dune formations have reached 1,000 feet in
straight parallel ridges (fig. B-2c), and stronger
height. The three general types of sand dunes are
described below; only the third type requires control.
B-1
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