Drainage Patterns

The arrangement of river networks within a drainage basin forms the drainage pattern, which reflects the underlying rock structure, slope, and geological history. India exhibits multiple patterns across its physiographic divisions.

4.1 Types of Drainage Patterns in India

1. Dendritic

• Resembles tree branches; develops where rock types offer uniform resistance
• Most common pattern in India — entire Ganga Plain and Peninsular rivers on uniform substrate
• Example: Ganga and its tributaries across UP, Bihar; Godavari system

2. Trellis

• Primary streams flow parallel; secondary tributaries join at right angles
• Develops in folded/tilted rock formations (ridges and valleys alternating)
• Example: Rivers in the Appalachians-equivalent terrain; Chhota Nagpur edge rivers

3. Radial

• Rivers flow outward from a central elevated point in all directions
• Example: Rivers originating from Amarkantak plateau — Narmada (west), Son (north), Johilla (east), Mahanadi (south-east)

4. Centripetal

• Rivers drain into a central basin or lake (opposite of radial)
• Example: Rivers draining into Sambhar Lake (Rajasthan), Loktak Lake (Manipur)

5. Parallel

• Rivers flow parallel to each other, often on a uniform steep slope
• Example: Punjab rivers (Ravi, Beas, Sutlej, Chenab) flowing southwest in parallel

6. Barbed/Rectangular

• Tributary joins the main stream at sharp angles due to jointing in rocks
• Example: Some rivers in the Deccan Plateau with prominent joint systems

4.2 Types of Drainage Based on Stream Relationship

Type	Definition	Example
Antecedent	River older than mountains; maintains old course by cutting through uplifting ranges	Indus, Sutlej, Brahmaputra — predate Himalayas
Consequent	Follows original slope of landscape	Most Peninsular rivers following Deccan slope
Subsequent	Developed after main stream; follows weak rock belt	Yamuna tributaries following Vindhyan structure
Superimposed	River imposed on rocks below from original surface	Son river in Vindhyan area
Misfit	River too small for its valley (valley cut by larger past river)	Many rivers in Rajasthan

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