afluente

An afluente is a river or stream that flows into a larger river or lake, thereby increasing its discharge and contributing to its drainage basin. The term is used primarily in Spanish- and Portuguese-speaking contexts; in English, the corresponding term is tributary. Afluentes can vary widely in size and flow regime, from large rivers to small streams. They join the main stem at points called confluences. A river system typically contains many afluentes, which can be perennial (flow year-round) or seasonal, depending on climate and groundwater input. In some contexts, afluentes are classified by their relative size or by order within a river network, with the largest being called afluentes principales or major tributaries.

Hydrologically, afluentes influence the discharge, sediment load, and nutrient transport of the main river. They shape channel morphology, flood dynamics, and ecological connectivity. Mapping afluentes is fundamental for understanding watershed boundaries and for managing water resources, flood control, and habitat conservation.

Notable examples include the Missouri River as a major afluente of the Mississippi River in North America; the Iguaçu River as a significant afluente of the Paraná; and the White Nile and Blue Nile as major contributors to the Nile system.

The word afluente derives from Latin affluere “to flow toward,” via Spanish and Portuguese; cognate terms in other languages reflect the same concept.