Aqueduct

The first record of an aqueduct appeared in 691 B.C. in Assyria. This 34 mi (55 km) long aqueduct was simple, consisting of a single arch over one valley. At that time, Greeks were using wells to retrieve water from underground pools. Certain plants, such as fig trees, marked water sources because their roots grow in water. The first Greek aqueduct followed in 530 B.C. on the island of Samos. This aqueduct was built by an engineer named Eupalinus, who was told to supply the city with water by tunneling a pathway through a mountain. The Samos aqueduct extended for about 1 mi (1.6 km) underground, and had a diameter of 8 ft (2.4 m). These first aqueducts demonstrated an understanding of siphons and other basic hydraulic principles.

While ancient Roman aqueducts evolved into an extensive network of canals supplying the city, the first one, the Aqua Appia, was not built until 312 B.C. This aqueduct was a simple subterranean covered ditch. Roman aqueducts were usually built as open troughs, covered with a top, and then covered with soil. They were made from a variety of materials including masonry, lead, terra cotta, and wood. The Appia was about 50 ft (15 m) underground to make it inaccessible to Roman enemies on the city's outskirts. The Anio Vetus, built in 272 B.C., brought more water to the city, but both the Appia and the Vetus had sewer-like designs. The Aqua Marcia, built in 140 B.C., was made of stone and had lofty arches. The Aqua Tepula of 125 B.C. was made from poured concrete. Later Roman aqueducts were mainly built to meet the needs of the people or the desires of the rulers of the time. The average Roman aqueduct was 10–50 mi (16–80 km) long with a 7–15 sq ft (0.7–1.4 sq m) cross-section. Aqueducts were generally wide enough for a man to enter and clean.

Around the world, communities made advances in irrigation and water management. In the Mexican Tehuacan Valley, evidence of irrigation dates back to The Pont du Gard, a Roman aqueduct in Nimes, France, dates from the first century A. D. Photograph by John Moss. National Audubon Society Collection/Photo Researchers, Inc. Reproduced by permission. around 700 B.C. in the remains of the Purron Dam. The dam was used to direct water to domestic and crop regions for several hundred years. In the same valley, the Xiquila Aqueduct was built around A.D. 400. Early North American aqueducts include the Potomac aqueduct in Washington, DC. This aqueduct, which was built in 1830, extends over the Potomac River at the Key Bridge, which joins Northern Virginia and the Georgetown area of the city. It was built with support from eight piers and two stone abutments to carry water from the upper Potomac to the city.

Later aqueducts of the United States include the Colorado River Aqueduct that supplies Los Angeles and the Delaware River Aqueduct that carries water into New York. In addition, aqueducts carry water from northern to southern California. The southwestern region of the United States is particularly dry and requires water import. Water can be collected from aquifers (underground water reservoir), rivers, lakes, or man-made reservoirs.