Over the next 450 miles (750 km), from the Guaharibos rapids to the Atures rapids, the Orinoco runs west until the Mavaca river joins it and the waters turn north. Other tributaries like the Ocamo join in and the river widens to 1320 ft (500 m) and sandy sediment forms little islands in the riverbed. The Casiquiare and Esmeralda (see map) rivers flow out of the Orinoco to join with another to form the Rio Negro which eventually reaches the Amazon.
The Cunucunuma river joins it, and the Orinoco veers to the northwest, bordering the Guyanese Shield. The Ventuari river brings with it enough sand to form the beaches at San Fernando de Atabapo. Where the Atabapo, Guaviare (see map) and Irínida rivers join the flow, the Orinoco widens to almost 5000 ft (1500 m).
Most of the Venezuelan aboriginal population lives within the Orinoco River basin. The most important indigenous groups include the Guaica (Waica), also known as the Guaharibo, and the Maquiritare (Makiritare) of the southern uplands, the Warrau (Warao) of the delta region, and the Guahibo and the Yaruro of the western Llanos. These peoples live in intimate relationship with the rivers of the basin, using them as a source of food as well as for purposes of communication. (Encyclopedia Britannica)
More tributaries flow in, increasing water flow and creating a new set of powerful rapids at Maipures and Atures across from Puerto Ayacucho. (see map) This is the only place where the Orinoco is not navigable. (see map)
Bajo Orinoco
Extending from the Atures rapids to Piacoa, this 570 mi (950 km) accepts the bulk of the tributary rivers. Where the Meta joins in, the river turns northeast, and with the Cinacuro, Capanaparo and Apure rivers, turns east. (see map) The Manzanares, Iguana, Suata, Pao, Caris, Caroní, Paragua, Carrao, Caura, Aro and Cuchivero rivers add to the Orinoco's bulk. The river here is wide and slow. (see map)
This section of the Orinoco is the most developed and populated. Since the oil strikes in the mid 20th century, the industrialization, commercialization and population has grown. Ciudad Bolívar and Ciudad Guayana have developed into important cities, built high enough away from the river banks to prevent flooding.
Among the islands in the river at Ciudad Bolívar is the one Alexander von Humboldt named Orinocómetro. It serves as a measurement tool for the rise and fall of the river. There are no actual seasons along the Orinoco, but the rainy season is referred to as winter. It begins in April and lasts to October or November. The rain-swollen torrents from the highlands carry dirt and rocks and other material from the highlands into the Orinoco. Unable to handle this excess, the river rises and floods the llanos and surrounding areas. The highest water period is normally in July, when the water level at Ciudad Bolívar can go from 40 to 165 feet in depth. The waters begin to recede in August, and by November are again at low point.
Founded in 1961, Ciudad Guayana, downstream from Ciudad Bolívar, produces steel, aluminum, and paper, thanks to power generated by the Macagua and Guri dams on the Caroní River. Growing into Venezuela's fastest growing city, it sprawls over the river and has incorporated the sixteenth century village of San Félix on one side and the new city of Puerto Ordaz on the other. There is a major highway between Caracas and Ciudad Guayana, but much of the area's transportation needs are still served by the Orinoco.
This Virtual Tour gives you an idea of both river and industrial growth in the state of Bolívar.
