tributarie

A tributary is a stream or river that flows into a larger river or lake. It contributes water, sediment, and nutrients to the downstream system, and its waters continue downstream through the main stem until they reach a larger body of water or the sea. The point where two streams meet is called a confluence.

Tributaries form the network of streams that drain a landscape, collectively known as a drainage basin or watershed. The main river, or trunk, collects discharge from its tributaries. The arrangement of tributaries and confluence points creates a hierarchical river system that shapes landscapes through erosion and deposition.

Tributaries vary in size and permanence. They can be perennial, flowing year-round, or intermittent and seasonal. Hydrologists classify streams by order, such as the Strahler method, in which the confluence of smaller streams increases the order of the river. Tributaries may be named or unnamed, and they can be affected by human activity such as damming and water withdrawals.

Ecologically, tributaries influence habitat availability, biodiversity, and nutrient cycling. They affect flood dynamics, sediment transport, and water quality for downstream ecosystems and human use. Changes in climate, land use, or hydrological engineering can alter tributary discharge, timing of flows, and sediment loads.

Notable examples include the Missouri and Ohio rivers, which are major tributaries of the Mississippi, and the Inn and Isar, tributaries of the Danube. These networks illustrate how tributaries integrate into broader river systems and support regional hydrology and ecology.