In a land as arid as Saudi Arabia construction of a dam may sound like a superfluous undertaking. But not in Jaizan.
Jaizan is a green plain down by the southeastern edge of the Red Sea. Unlike the rest of the kingdom it receives heavy seasonal rainfalls, most of which, until three years ago, ran off uselessly into the sands.
In the winter of 1971, however, top officials from Saudi Arabian ministries gathered in Jaizan to mark the completion of the Wadi Jaizan project—a project intended to harness that precious, previously wasted rainfall and channel it into the irrigation needed for a significant increase in the areas' agricultural output.
The dam had been planned ever since the United Nations Food and Agriculture Organization conducted a preliminary study and concluded that a dam in the area might be of value. Acting on that conclusion, officials in the Saudi Arab Government brought in Ital-Consult, a major Italian engineering firm, and requested detailed feasibility studies.
After studying the area thoroughly, Ital-Consult zeroed in on a site tucked between mountain ridges about 30 miles east of the city of Jaizan at an elevation some 450 feet above sea level. That done, the firm went ahead with a design. When the design was finished the government accepted a bid from Hochtief, a German firm, and in 1967 work was begun.
For Hochtief, the first step was to provide a solid foundation. To do so the firm's engineers ordered drills into action and excavated nearly 4,350,000 cubic feet of earth and rock. Another 4,233,000 cubic feet of rock were blasted, crushed—and then washed—to provide raw material for the 5,121,400 cubic feet of concrete that went into the body of the dam.
Work went slowly at first, but eventually the dam began to take shape. When it was finished it measured 1,036 feet across the top, was nearly 13 stories high and had a base 131 feet thick.
Behind the dam was a new reservoir, then still dry, with a capacity of 2,507,000,000 cubic feet or nearly 19 billion gallons. Poured carefully through gates in two spillways at the base of the dam, some 1,800,000,000 cubic feet of water—close to 13½ billions gallons—can provide irrigation for more than 3,000 acres of land.
In comparison with other dams in the Middle East the Jaizan Dam is hardly a monumental project. In Egypt the overwhelmingly bigger Aswan High Dam is 364 feet high, 1,800 feet bank to bank and is two thirds of a mile thick at the base. It includes a 130-foot-wide, two-mile-long highway across the crest, and has provided Egypt with 320-mile-long Lake Nasser, one of the world's largest reservoirs. In addition, there is a complex of downstream turbines that in 1970 added 10 billion kilowatt hours to Egypt's power capacity. In Syria, the recently completed Tabqa or al-Thawra Dam, is possibly the largest earth dam in the world: 2.6 miles across and 196 feet high, with a reservoir 49 miles long, enough to double the country's irrigation, and an electricity complex that will triple the country's power output.
Nevertheless for Saudi Arabia, which has no rivers of any size, let alone the Euphrates or the Nile, the Jaizan Dam is still an important project. It has, for example, already blunted the dangers and sharply reduced the waste of the flash flood, that phenomenon of arid lands. Flash floods occur because in countries such as Saudi Arabia where there are virtually no trees, and only sparse vegetation to absorb excess rainfall, the runoff races swiftly into wadis and valleys, builds up a head of water, sweeps downstream at an incredible and destructive rate and is dissipated in the sand. In the Jaizan area the dam has all but eliminated the incidence of such floods.
The dam's chief role, however, is in agriculture. If it fulfills expectations it will nourish precious farmland, encourage the introduction of new crops and make rural and agricultural industries possible. Furthermore, the Jaizan project is serving as a model for eight more dams now being planned or under construction. These are al-Alab and al-Hair dams in the Hanifa Valley, the Shaqra Dam, the Glagil Dam in al-Gaht, the Thadek Dam, the Wadi Saab Dam, the Liyab Dam and the Mared Dam. Seven of the dams are being designed to recharge wells, some to provide drinking water, some to provide irrigation. The Mared Dam, with a complex of dikes and spurs, is to provide flood control.
But above all the Jaizan project is a stride toward one of the kingdom's goals: the utilization of every asset in the country for the betterment of the country's people.