Arauca Department in the context of Boyacá Department

The Orinoquía region is one of the six natural regions of Colombia that belongs to the Orinoco River watershed. It is also known colloquially as the Eastern Plains (Llanos Orientales). The region covers most of the area of the departments of Arauca, Casanare, Meta, and Vichada and small parts of the Boyacá, Norte de Santander, and Cundinamarca departments.

The Meta River is a major left tributary of the Orinoco River in eastern Colombia and southern Venezuela, South America. The Meta originates in the Eastern Ranges of the Andes and flows through the Meta Department, Colombia as the confluence of the Humea, Guatiquía and Guayuriba rivers. It flows east-northeastward across the Llanos Orientales ("Eastern Plains") of Colombia following the direction of the Meta Fault. The Meta forms the northern boundary of Vichada Department, first with Casanare Department, then with Arauca Department, and finally with Venezuela, down to Puerto Carreño where it flows into the Orinoco.

The Meta River is 1,100 km (680 mi) long and its drainage basin is 103,000 km (40,000 mi). The Meta divides the Colombian Llanos in two different parts: the western portion on the left bank is more humid, receives the relatively nutrient-rich sediments from the Andean mountain range and therefore soils and tributaries are also nutrient-rich, while the eastern portion, high plain or altillanura, drains not to the Meta river but to the Orinoco, has a longer dry season and soils and surface waters are oligotrophic (nutrient poor).