World Geography : Drainage Patterns and System . ( UPSC )

Flow of water through well defined channel is called drainage.

• The area drained by a main river and its tributaries, the entire area from where water collects in the main river is called catchment area.
• The imaginary line that separates one drainage basin from another is called a watershed.

Drainage Pattern

• Drainage pattern a pattern created by stream erosion over time.

1. Dentritic

• There is a main stream from which all the tributaries come together.

2. Pinnate

• Like a bird’s wing or a bird’s veins.
• Son river and Narmada runoff.

3. Trellis

• Tributaries meet at right angles to the main river in the rift valley.

4. Rectangular

• In this also the tributaries meet at right angles to the main river, but the angle of joining it depends on the joints of the rocks.

5. Radial/ Centrifugal

• In this type of pattern, the rivers flow from one place and flow around.
• Ranchi Plateau, Hazaribagh Plateau, Amarkantak Plateau.

6. Centripetal

• In this type of pattern, rivers start falling in a trough or lake.

7. Annular

• In such a pattern, it flows in the shape of a circle revolving around the dome.

8. Barbed

• If the direction of the tributaries is opposite to the direction of the main river.
• Several tributaries in the upper reaches of the Indus and Brahmaputra

9. Herring’s Bone Drainage Model

• This pattern is formed in mountain ranges.
• Ex-Jhelum River.

10. Parallel Drainage Pattern

• Rivers of the Western and Eastern Coastal Plains.

11. Intermittent

• In the desert parts, the seasonal water current disappears midway instead of meeting the sea.
• The river also becomes extinct for some time in Bhabar region.

12. Underground Drainage Pattern

• The surface water level goes underground in the lime rock area

Drainage System

• Patterns formed by the streams, rivers, and lakes in a particular drainage basin.
• The following two types:

A. Sequential/ concordant drainage system

• It flows along the slopes.
• They are of the following types:

1- Consequent

• Rivers arising after uplift of topography.
• Follow the territorial slope.
• Rivers flowing in the peninsular plateau like Narmada, Tapti, Godavari, Krishna and Kaveri.

2- Subsequent

• Joins the following river at right angles.
• The Chambal, Sind, Ken, Betwa, Tons and Son meet the Yamuna and the Ganga at right angles.

3- Obsequent

• River flowing in the opposite direction of the main follower river.
• Meets the subsequent river at right angles.

4- Resequent

• Their direction is according to the flow direction of the main consequent river.
• Flows along the regional slope.

B. Insequent drainage system

• It flows in the opposite direction of the slope.
• They are of the following types:

1. Antecedent / Discordant River

• Their origin occurs before the uplift of the site block.
• Himalayan rivers like Ganga, Brahmaputra, Indus.
• It flows independently of the slope.

2. Superimposed

• When a river flowing over a softer rock stratum reaches the harder basal rocks but continues to follow the initial slope.
• It seems to have no relation with the harder rock bed.
• The Damodar, the Subarnarekha, the Chambal, the Banas and the rivers flowing at the Rewa Plateau present some good examples of superimposed drainage.