Hydrographic basin  

Concept

Bacia hidrográfica -

Hydrographic basin –  lands drained by a  main river,  its affluents and sub-affluents. The idea of a hydrographic basin is  associated with the following features:   water springs existence,  dividers and the  presence of main and secondary streams, called affluents and sub-affluents.

 A hydrographic basin  evidences the hierarchical organization of rivers,  that is, the natural organization  by order from the ones of lesser volume to those carrying much more water, usually going from the highest  regions to the lower ones.

 Basins can be  divided by their importance,  such as the main (those that bear the major volume rivers),  secondary  and thirds  according to their localization, such as in the shore or in the country  side.

In basins with significant inclination like  the Colorado River, in the United States,  a process called search of fluvial balance profile tends to narrow the basin area. Instead, low inclination basins such as the Amazon, tends to be  Widen that area.

Source: Enciclopédia® Microsoft® Encarta 2001. © 1993-2000 Microsoft Corporation