Sustainable Water Management for the Paso del Norte Border Region

The Rio Grande basin and its drainage network.

The Rio Grande basin and its drainage network.

Copyright (c) 1996 Encyclopaedia Britannica, Inc. All Rights Reserved

The Rio Grande, the fifth longest river of North America and the 20th longest in the world, forms the entire border between the U.S. state of Texas and Mexico (in which country it is known as the Río Bravo del Norte). The area within the entire watershed is some 336,000 square miles (870,000 square kilometres). Because a large proportion of the river's basin is arid or semiarid, however, only about half of the total area, or about 176,000 square miles, actually contributes to the river's flow. Rising as a clear, snow-fed mountain stream more than 12,000 feet (3,700 metres) above sea level in the Rocky Mountains of Colorado, the Rio Grande descends across steppes and deserts, watering rich agricultural regions as it flows on its way to the Gulf of Mexico; the total length of the river is 1,760 miles (2,830 kilometres).

Rio Grande,

Spanish RÍO GRANDE DEL NORTE, or (in Mexico) RÍO BRAVO, or RÍO BRAVO DEL NORTE, one of the longest rivers of North America, flowing 1,760 miles (2,830 km) from its sources in the southern Rocky Mountains of southwestern Colorado to the Gulf of Mexico and marking the entire border between Texas (U.S.) and Mexico.

The Rio Grande rises as a clear, snow-fed stream more than 12,000 feet (3,700 m) above sea level in the San Juan Mountains of Colorado and flows generally southward across Colorado and New Mexico. For the lower two-thirds of its course, the Rio Grande flows southeastward between Texas and the Mexican states of Chihuahua, Coahuila, Nuevo Léon, and Tamaulipas to eventually empty into the Gulf of Mexico. Its early course flows through forests of spruce, fir, and aspen into the broad San Luis valley in Colorado, after which it cuts the Rio Grande Gorge and White Rock Canyon of northern New Mexico and enters the open terrain of the Basin and Range and the Mexican Plateau physiographic provinces. Shortly before entering the Gulf coastal plain, the Rio Grande cuts three canyons between 1,500 and 1,700 feet (457 and 518 m) in depth across the faulted area occupied by the "big bend" region along the Texas-Mexico border. Along the remainder of its course, the river wanders sluggishly across the coastal plain to its delta on the Gulf of Mexico.

The principal tributaries of the Rio Grande are the Pecos, Devils, Chama, and Puerco rivers in the United States and the Conchos, Salado, and San Juan in Mexico. The basin of the Rio Grande drains an area of about 336,000 square miles (870,000 square km), although only about half of this area contributes to the river's flow. The river's peak flow occurs from about April to October. Roughly one-third of the Rio Grande's water reached the Gulf of Mexico before the building of the Falcon Dam (1953) upstream from Rio Grande City; the river's average discharge rate is now about 3,000 cubic feet (85 cubic m) per second.

More than 2,000,000 acres (800,000 hectares) of farmland are irrigated along the Rio Grande, with slightly more than half in Mexico. The leading crops raised by irrigation vary from potatoes and alfalfa in Colorado to cotton, citrus fruits, and vegetables along the lower Rio Grande. After agriculture and animal husbandry, the region's main industries are mining and recreation.