Drainage Basins

River Drainage

· All the land drained by a river and its tributaries is known as a drainage basin.

· The high land which separates one drainage basin from another is called a watershed or divide.

· A river is a body of water which flows in a channel and through which excess water is drained away from the land.

· The place where a river begins is called its source. A source may be a spring, a lake

· The place where a river ends is called its mouth. A mouth could be the sea, an ocean or a lake.

· A river which flows into another river is known as a tributary.

· The place where a tributary joins a larger river is called a confluence.

Drainage Patterns

1) Dendritic Pattern

- Many contributing streams which join the main river.

- Resembles the branches or roots of a tree.

- Commonly found on relatively gentle slopes with uniform geology.

- Eg. Caroni River, Trinidad

2) Radial Pattern

- Streams flow from a central peak

- Common in areas with volcanic cones or conical landforms.

- Eg. Streams running from Nevis Peak, Nevis and Soufriere Hills, Montserrat.

3) Trellis Pattern

- Forms when streams join the main river at right angles.

- Common in areas with alternating hard and soft rock.

- Eg. Streams in the northern section of Trinidad