The construction of the Marib Dam in Yemen provided water for irrigation for nearly one thousand years and created a rich farming region on the edge of the desert in south-central Arabia.

The area around the ancient city of Marib has been important commercially and agriculturally for several thousand years. Once known as Sheba (or Sabah, or Sabaa), the region lay on trade routes stretching by sea to the Persian Gulf and India and by land to Mesopotamia and the eastern shores of the Mediterranean. Equally important, Sheba was a rich agricultural region. The Old Testament of the Bible records a queen of Sheba, believed to have lived about 950 b.c.e., as visiting Solomon, king of Israel. Today the region lies in the nation of Yemen in southern Arabia.

Heavy rains fall in Yemen only two or three times a year, briefly flooding the hills only to disappear into the sand or evaporate. In order to channel this water for farming, Sheba’s inhabitants developed an extensive and sophisticated irrigation system, some of whose diversion dams and canals have been dated to the middle of the third millennium b.c.e.

The greatest component of Sheba’s irrigation system was the Marib Dam, built about 5 miles (8 kilometers) west of Marib across the Wadi (watercourse) Adana. The Adana flows in a northeasterly direction from the eastern highlands of Yemen and gathers the runoff of many other wadis. The original earth dam, which was begun about 750 b.c.e., was about 13 feet (4 meters) high and 1,900 feet (580 meters) long. It fed water into a single, naturally occurring spillway lying nearly 10 feet (3 meters) below the top of the dam and located between the northern end of the dam and a high cliff. The water then flowed into a basin 75 feet (23 meters) wide and 213 feet (65 meters) long in which silt could settle. A canal 92 feet (28 meters) wide and 3,068 feet (935 meters) long led from the basin to twelve separate ditches. As a result, Sheba’s inhabitants were able to bring the land north of the wadi under cultivation.

Some two and a half centuries later, beginning about 500 b.c.e., the dam was heightened to 23 feet (7 meters). The slope of its sides now lay at about 45 degrees, and its upstream surface was faced with stone set in mortar to prevent seepage and erosion. A sluice was cut and an adjoining canal built at the dam’s southern end, allowing for irrigation of the southern banks of the Wadi Adana. Later construction raised the height of the dam to 46 feet (14 meters) and improved the irrigation system’s efficiency.

Thanks to the dam and its extensive series of canals, settling ponds, and ditches, much of the rainwater falling in the highlands of Sheba was caught and channeled to the lands around Marib. Although the region lay at the edge of the forbidding desert known as the Rub al Khali, or Empty Quarter, it grew into a rich farming community. Some 24,000 acres (9,600 hectares) were brought under cultivation, an area large enough to feed as many as fifty thousand people. The region’s farmers produced barley, maze, millet, dates, grapes, and other crops. The immense structure that made this possible came to be known simply as the Great Dam, and the fertile lands north and south of the Wadi Adana were known as the Garden of the Two Paradises.

The accumulation of silt and other debris was cleared from behind the dam every one hundred years. Unusually heavy floods overtopped the dam more frequently, approximately every fifty years, necessitating periodic repairs. However, the damage caused by a major flood in 575 c.e. was never repaired, and subsequently the dam washed away. The loss was devastating, an event so catastrophic that it is memorialized in the Qur՚ān, the Muslim holy book. Most inhabitants fled the region.

Beginning in 1984, a new earth dam was built across the Wadi Adana upstream from the location of the ancient structure.

• Clapp, Nicholas. Sheba: Through the Desert in Search of the Legendary Queen. Boston: Houghton Mifflin, 2001. Popular account of a journey through the lands associated with the queen of Sheba, with a chapter devoted to Marib and its dam. Photographs, plans, and extensive bibliography.
• Dayton, J. E. “A Discussion of the Hydrology of Marib.” Proceedings of the Seminar for Arabian Studies 9 (1979): 124-129. Examines possible causes for the destruction of the dam. Includes two plans of the south sluice and a photograph.
• Dayton, J. E. “Marib Revisited.” Proceedings of the Seminar for Arabian Studies 11 (1981): 7-26. Summary of a brief visit to the site in 1979. Plans and numerous photographs.
• Ganchikov, V. G., and Z. I. Munavvarov. “The Marib Dam (History and the Present Time).” Hydrotechnical Construction 25 (1991): 242-248. Discusses the ancient dam and its modern counterpart. Includes plans, excellent drawings, a cross section of the ancient dam, a schematic cross section of the modern dam, and a table summarizing its measurements.
• Hehmeyer, Ingrid. “Irrigation Farming in the Ancient Oasis of Marib.” Proceedings of the Seminar for Arabian Studies 19 (1989): 33-44. Analyzes the irrigation systems in use in ancient Marib, methods of preparation of the soil, and the variety of crops grown.
• Schnitter, Nicholas J. Dams: The Useful Pyramids. Rotterdam, The Netherlands: A. A. Balkema, 1994. Discusses the Marib Dam as one of several ancient dams. Includes a photograph, detailed plan of the dam in its final configuration, table of other dams in the area, and bibliography.
• Smith, Norman. A History of Dams. Secaucus, N.J.: Citadel Press, 1972. Smith devotes several pages to the Marib Dam in his survey of the dams of antiquity, discussing its construction, maintenance, and eventual abandonment.