Charting shifts of sand a vital tool to protect projects from dunes
Dhahran, Saudi Arabia
Every so often, Dr. Danilo J. Anton heads off into the desert and sets up a bunch of sand traps. ''Saudi Arabia must be the only place in the world where you trap sand,'' reckons Dr. Anton, a Uruguayan-born scientist who is at the Research Institute of the University of Petroleum and Minerals here.
But in this desert land, where sand dunes might climb as high as 800 feet, the movement of sand is important. The railway across this wide Arabian Peninsula pays millions of dollars each year to keep its tracks free of sand. Roads must be constructed so that sand blows across them. Otherwise, small piles of wind-blown sand can be hazardous to traveling motorists. After the ''shamals, '' the northerly summer winds, have kicked up a sandstorm, municipalities here must clean up, much like a Midwestern town in the United States may cart away the snow from its streets after a blizzard.
The sand traps, placed by Dr. Anton or his colleagues at the institute, are intended to provide information on the direction and quantity of blowing sand. With such information, scientists can offer better advice either on where to locate, say, a new road, or on how to stop the sand from piling up on a road.
A sand dune, noted Dr. Anton, can move 110 to 130 feet a year. Once such a dune shifted onto a road or an airport, for instance, it could be costly to remove.
The university's Research Institute is housed in one of the most advanced scientific facilities in the Middle East. Besides doing research on sand, the 190 members of its staff are looking into other areas of practical use for the kingdom. For instance, it has been studying such matters as how to calculate oil spill paths; how to adapt solar technology to dust-blown regions; how to control corrosion in an area crisscrossed with myriad steel pipelines carrying water, oil, and gas; and how to preserve the fragile desert environment.
The multidisciplinary staff is partly financed by research contracts awarded by the government or such major corporations as Aramco, the oil company whose headquarters complex is next to the university.
One such contract, for 5 million Saudi riyals ($1.5 million), called for a comprehensive examination of potential sand problems at the new international airport under construction near here. That involved setting up some 120 sand traps and doing analysis with hydrogeology (checking underground water levels with 120 small wells), using information from the Landsat satellite of NASA; topographic surveying, geology, and geomorphology (shape of the earth). The final report involved some 100 maps and 10 volumes.
There are several basic means of controlling sand movement.
1. Using desert vegetation, such as grasses or bushes, to anchor the sand.
''These plants are really tough,'' Dr. Anton said. ''Some species are unbelievable.''
One plant grows above the ground six or eight inches, but its roots stretch perhaps 45 feet in the search for water.
In the case of the airport, the scientists recommended fencing off a portion of the area to prevent camels, sheep, or goats from grazing on the vegetation. It was found that little would be needed in the way of irrigation.
2. Spraying chemicals or crude oil on the sand.
''That's very effective for four, five, or six years,'' Dr. Anton said. ''But it is a sticky mess.''
By spraying strips of chemical on a dune, it can sometimes be destroyed. The wind carries away the sand between the sprayed strips and the whole dune is eventually blown away.
3. Installing ''snow'' fences in an area vulnerable to sand movement. These slow the wind, and the sand falls to the ground, much as happens with snow in colder climes.
Dr. Anton noted that a space must be left under the sand fence and this covered with chemical. Otherwise, the wind will scour out a trench and the fence will collapse.
The scientists have been experimenting with using palm leaves as fences. One problem, however, is that camels will eat them. ''Camels eat almost everything, '' said Dr. Anton.
Wooden slat fences require less maintenance.
He and his colleagues are doing more sand research in connection with the new industrial town of Al Jubayl, north of here, with the new highway to Riyadh, and they have had some inquiries from the railway.
In protecting highways from sand, the key is to keep the slope of the shoulder less than 7 degrees. The sand will blow up that slope and across the highway.
The research is not entirely hazard free. In summer, the desert can be extremely hot - temperatures well above 100 degrees F. Two of Dr. Anton's colleagues were doing some research in a remote corner of the future airport when their vehicle got stuck in the sand. They were perhaps 15 miles from a road , a distance almost impossible to walk across in the blazing sun. Their radio, a standard safety measure for those working in the desert, was broken. By the time they got the vehicle free, the two had drunk 2.5 gallons of water. ''They were real worried,'' Dr. Anton said.