(Adapted from the U.S. Army Survival Manual)
To survive in arid or desert areas, you must understand and
prepare for the environment you will face. Your survival will
depend upon your knowledge of the terrain, basic climatic elements,
your ability to cope with these elements, and your will to survive.
Most arid areas have several types of terrain. The five basic
desert terrain types are -
Mountainous (High Altitude).
Broken, dissected terrain ( "gebel" or "wadi"
Desert terrain makes movement difficult and demanding. Land navigation
will be extremely difficult as there may be very few landmarks.
Cover and concealment may be very limited; therefore, the threat
of exposure to the enemy remains constant.
Scattered ranges or areas of barren hills or mountains separated
by dry, flat basins characterize mountain deserts. High ground
may rise gradually or abruptly from flat areas to several thousand
meters above sea level. Most of the infrequent rainfall occurs
on high ground and runs off rapidly in the form of flash floods.
These floodwaters erode deep gullies and ravines and deposit
sand and gravel around the edges of the basins. Water rapidly
evaporates, leaving the land as barren as before, although there
may be short-lived vegetation. If enough water enters the basin
to compensate for the rate of evaporation, shallow lakes may
develop, such as the Great Salt Lake in Utah, or the Dead Sea.
Most of these lakes have a high salt content.
Rocky Plateau Deserts
Rocky plateau deserts have relatively slight relief interspersed
with extensive flat areas with quantities of solid or broken
rock at or near the surface. There may be steep-walled, eroded
valleys, known as wadis in the Middle East and arroyos or canyons
in the United States and Mexico. Although their flat bottoms
may be superficially attractive as assembly areas, the narrower
valleys can be extremely dangerous to men and material due to
flash flooding after rains. The Golan Heights is an example of
a rocky plateau desert.
Sandy or Dune Deserts
Sandy or dune deserts are extensive flat areas covered with
sand or gravel.
"Flat" is a relative term, as some areas may contain
sand dunes that are over 300 meters high and 16 to 24 kilometers
long. Traffic ability in such terrain will depend on the windward
or leeward slope of the dunes and the texture of the sand. Other
areas, however, may be flat for 3,000 meters and more. Plant
life may vary from none to scrub over 2 meters high. Examples
of this type of desert include the edges of the Sahara, the empty
quarter of the Arabian Desert, areas of California and New Mexico,
and the Kalahari in South Africa.
In a desert area there are seven environmental factors that
you must consider -
Intense sunlight and heat.
Wide temperature range.
High mineral content near ground surface.
Low rainfall is the most obvious environmental factor in an
arid area. Some desert areas receive less than 10 centimeters
of rain annually, and this rain comes in brief torrents that
quickly run off the ground surface. You cannot survive long without
water in high desert temperatures. In a desert survival situation,
you must first consider "How much water do I have?"
and "Where are other water sources?"
Intense Sunlight and Heat
Intense sunlight and heat are present in all arid areas. Air
temperature can rise as high as 60 degrees C (140 degrees F)
during the day. Heat gain results from direct sunlight, hot blowing
winds, reflective heat (the suns rays bouncing off the
sand), and conductive heat from direct contact with the desert
sand and rock.
The temperature of desert sand and rock averages 16 to 22
degrees C (30 to 40 degrees F) more than that of the air. For
instance, when the air temperature is 43 degrees C (110 degrees
F), the sand temperature may be 60 degrees C (140 degrees F).
Intense sunlight and heat increase the bodys need for
water. To conserve your body fluids and energy, you will need
a shelter to reduce your exposure to the heat of the day. Travel
at night to lessen your use of water.
Radios and sensitive items of equipment exposed to direct
intense sunlight will malfunction.
Wide Temperature Range
Temperatures in arid areas may get as high as 55 degrees C
during the day and as low as 10 degrees C during the night. The
drop in temperature at night occurs rapidly and will chill a
person who lacks warm clothing and is unable to move about. The
cool evenings and nights are the best times to work or travel.
If your plan is to rest at night, you will find a wool sweater,
long underwear, and a wool stocking cap extremely helpful.
Mirages are optical phenomena caused by the refraction of
light through heated air rising from a sandy or stony surface.
They occur in the interior of the desert about 10 kilometers
from the coast. They make objects that are 1.5 kilometers or
more away appear to move.
This mirage effect makes it difficult for you to identify
an object from a distance. It also blurs distant range contours
so much that you feel surrounded by a sheet of water from which
elevations stand out as "islands."
Light levels in desert areas are more intense than in other
geographic areas. Moonlit nights are usually crystal clear, winds
die down, haze and glare disappear, and visibility is excellent.
You can see lights, red flash-lights, and blackout lights at
great distances. Sound carries very far.
Conversely, during nights with little moonlight, visibility
is extremely poor. Traveling is extremely hazardous. You must
avoid getting lost, falling into ravines, or stumbling into enemy
positions. Movement during such a night is practical only if
you have a compass and have spent the day in a shelter, resting,
observing and memorizing the terrain, and selecting your route.
Steve's Notes: In the dry air of the desert, you
may not feel like you are sweating, because your perspiration
can evaporate as fast as it comes. This can be very comfortable
compared to the "sticky" heat of more humid areas.
It also means it is easy to become dehydrated very quickly without
realizing it is happening.
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