Canal

The earliest canals were built by Middle Eastern civilizations primarily to provide water for drinking and for irrigating crops. In 510 B.C. Darius I, King of Persia, ordered the building of a canal that linked the Nile River to the Red Sea; this canal was a forerunner of the modern Suez Canal. The Chinese were perhaps the greatest canal builders of the ancient world, having linked their major rivers with a series of canals dating back to the third century B.C. Their most impressive project was the famous Grand Canal, the first section of which opened around A.D. 610. With a total length of 1,114 ft (1,795 km), it is the longest canal in the world. Canals were employed by the highly practical Romans, but were neglected for the centuries after the fall of the Roman Empire. The commercial expansion of the twelfth century spurred the revival Canal in Delft, the Netherlands. The first network of canals was built in the thirteenth and fourteenth centuries in the Netherlands. Photograph by Porterfield/Chickering. The National Audubon Society Collection/Photo Researchers, Inc. Reproduced by permission. of canals, and it is estimated that as much as 85% of the transport in medieval Europe was by canal.

Many early canals were called contour canals because they followed the lay of the land and simply went around anything in their way. Major changes in ground and water levels have always presented canal builders with their greatest engineering problem; at first, boats were simply towed or dragged over slipways to the next level. The invention of the modern lock in China solved this problem at once, causing the full development of canals. The modern two-gate lock evolved from the slow and unsafe Chinese "flash lock" that had only one gate; the "flash lock" eventually made its way to Renaissance Europe, where it was modified with a second gate. The development of the lock heralded a period of extensive canal construction across Europe, and it is not surprising that each nation responded in its own particular way. The Naviglio Grande Canale in Italy (1179–1209) and the Stecknitz Canal in Germany (1391–1398) are two that made important contributions to waterway technology. Also in China, a 684 mi (1,100 km) branch of the Grand Canal was finished in 1293. Over the next few centuries, France built the pioneering Briare Canal (completed in 1642) and the famous Canal du Midi (1681), which joined the Mediterranean and the Atlantic and would serve the world as an example of complex civil engineering at its best. This remarkable French canal stimulated the era of British canal construction that began with the completion of the Bridgewater Canal (1761). In Germany, the Friedrich Wilhelm Summit Canal was completed in 1669, and in other nations, extensive waterway systems were developed. With industrial production steadily growing in the nineteenth century, transport by canal became essential to the movement of raw materials and goods throughout Europe.

The United States has a shorter tradition of canal building. Its first major canal was the Erie Canal, constructed during the beginning of the nineteenth century. Completed in 1824, the 364-mi (586 km) canal provided a water route that brought grain from the Great Lakes region to New York and the markets of the East. With the construction of railroads in the 1830s, the U.S. quickly abandoned its canals in the belief that rail would be the best method for every transport task. The Europeans did not react the same way to railroads, maintaining their canal systems as a complementary system not in competition with railroads. Today, inland waterways or canals play a major transportation role in the United States and the rest of the world, for it has been realized that canals are perfectly suited for carrying low-value and high-bulk cargoes over long distances.

Sea canals, the great canals that shorten sea routes, are glamorous and highly visible engineering achievements. Three well-known examples are the Kiel Canal connecting the North and Baltic Seas (1895), the Suez Canal linking the Mediterranean and Red Seas (1869), and the Panama Canal between the Atlantic and Pacific Oceans (1914). Sea-to-sea ship canals face the problem of obsolescence: some new ships are too large for old canals. Both the Kiel and the Suez canals have been enlarged, but the Panama canal is not large enough to accommodate the world's largest ships.