The Saudi Arabs regard the everlasting sands of their homeland in the same way that the Dutch look upon the sea or the Swiss upon the snow. Taken by the grain, the drop or the flake, these substances are harmless enough. But heap them up into massive bodies and they generate a formidable power that awes those who know them.
Sand dunes are a problem over much of the Arabian Peninsula, just as the angry waters behind the dikes menace the maritime Netherlands and just as avalanches hang ponderously over the heads of the upland Swiss. Rampaging waters and plummeting snowslides, electrically quick in their violence, are no more destructive than the banks of Arabian sand that move almost imperceptibly, choking whatever lies in their path. While no able-bodied townsman or Bedouin has ever been swallowed up by encroaching sand, the damage to their property and means of livelihood has been as enormous as that of flooded farmlands in the Low Countries or snow-drowned villages in the Alps. But today there is hope in the hearts of the Saudi Arabs: the Government has marshaled its finest forces to wage the life-and-death struggle.
How does one of these heavy-handed destroyers come into being? The genesis of a dune is still a matter of speculation, but geologists believe they originate when wind blows sand against an obstacle like desert brush. This insignificant hurdle often constitutes the tiny core of what may become a mammoth hill of sand anywhere from six to 700 feet in height.
The velocity and duration of the wind are chiefly responsible for the rate of sand accumulation and also account for the shape of a dune. Dunes are of two types—the stationary mountains or the migratory masses. And it is the wind which fashions their form as it relentlessly nudges the dunes across the wastelands of eastern Saudi Arabia.
Seen from above, a migratory dune usually assumes the shape of a crescent. The back stands against the wind; the front faces away from the wind's course. A crest running across the top from horn to horn separates back from front.
For the sand dunes to become mobile, the wind must be a prevailing one. If it shifts erratically, the pile of sand deposited by one breeze will be whipped off course by an opposing current. Variable winds weave irregular patterns into the sand mounds, often stretching them out into elongated ridges or heaping them into pyramids.
Eastern Saudi Arabia offers ideal conditions for the formation of migratory dunes—a superabundance of sand and a year-round prevailing wind.
This otherwise gloomy outlook is brightened by one ray of optimism, however. The movement of the sand is relatively predictable. Winds blow across the Peninsula in a predominantly southeasterly direction. The shamals (sandstorms) that whine for days on end are the breath of life for the dunes. They push the grains of sand together, coaxing them into mounds, then into hills and finally into mountains. They guide them to the Rub' al-Khali, that desert of deserts in the southeastern quadrant of Saudi Arabia. Here the wind becomes variable and breaks up the creeping crescents, rearranging them in jagged prominences haphazardly heaped around the vast wasteland that is the Empty Quarter.
A sand dune on the move goes through a tumbling process similar to the action of a modern washing machine. First a wind lifts grains of sand and they begin to gather around an obstruction. As the wind rises, the sand whirls faster and faster. The frenzied grains, escaping the wind's battery, trickle down the facade of the dune. Reaching the bottom, they are buried by other granules, each falling a fraction of an inch farther forward than its predecessor. Eventually the original grains are freed and pushed up to the top of the dune, only to slide down its face once again.
Sand dunes migrate at a speed practically microscopic to the casual observer. But the smaller the dune the faster its destructive progress. A crescent measuring 500 yards from horn to horn moves approximately 15 feet a year. Smaller dunes often race a distance of 60 feet in the same time.
The supply of sand never runs out. While the wind buffets the sand southward, new grains are being created through the erosion of rocks far to the north.
An airplane flight over the rim of the oil-producing region of eastern Saudi Arabia will bring home with tremendous impact the magnitude of the sand migration problem. From the cabin window a passenger can view one sprawling dune, sixteen miles long and four miles wide, looming like a frozen tidal wave. It stands poised at the doorways of a dozen villages. It has already spilled into irrigation ditches, cutting off drainage, clogging artesian wells and strangling crops. It has shouldered its bulk against the threshold of one of the Kingdom's most precious assets—an oasis. Creeping at a silent but nonetheless merciless pace, the tons of sand promise to engulf the al-Hasa Oasis unless the onward drive can be checked.
The Saudi Arab Government's Ministry of Agriculture has launched a five-year dune stabilization campaign to save the storied oasis from annihilation. A number of specialists from the Arabian American Oil Company are participating. Having waged a continuous fight against the sand forays around the oil installations to the north, the Aramco investigators have a good knowledge of the ancient, ever-present threat that faces them.
The experts envisage combating the invasion in four different ways:
One weapon is a by-product of the same substance that Saudi Arabia produces in tremendous quantities—oil. Spraying asphalt—a petroleum derivative—on the exposed surfaces of dunes slows them in their tracks. This method has been employed from time to time along the highways where trespassing sand threatens to obliterate the right-of-way.
Building sand fences, which break up the dunes' contours and thus reduce their accumulating mass, has proved quite successful in the past. The barriers resemble the ones set up in northern countries to hold back crushing snow drifts. But sand is even more crushing: it weighs up to ten times as much as snow and is difficult and costly to remove.
Earth-moving machinery will also be mustered into the conflict. This equipment will be called upon to flatten the dunes as much as possible and will dig deep trenches in front of the dunes to catch them in traps.
Another anti-sand device involves the planting of trees and shrubs ahead of the dunes' line of march, much as farmers in many parts of the world plant trees and hedge rows to protect fields from wind and snow. These obstacles help to spread the dunes asunder as they pass by.
The sand specter comes as no stranger to the Eastern Province. But now there is a possible means of solving it. This is an age-old enemy that lives on as the wind piles up new sand dunes and shoves them inch by inch toward that graveyard of the desert itself—the Empty Quarter. Who knows what fabled cities and temples these vagrant grains have buried, or what ancient tombs they have reburied? Perhaps the dunes have done their last mischief now that weapons against them are at hand. Everyone in the Eastern Province will be watching which way the tide will turn in the "battle of the dunes."