🌍🌍Drainage System and Patterns
🛑Sequent Drainage Systems
1. Consequent Streams
🟢Definition:-Consequent streams are the first streams that develop on a newly formed land surface. They flow in the direction of the original slope of the land.
🔰Features
1.Oldest streams in a drainage basin.
2.Flow along the natural gradient.
3.Usually form the main trunk river.
4.Develop immediately after land uplift.
⭐Examples:- East-flowing rivers of the Western Ghats (e.g., Godavari, Krishna, Kaveri)
🌟West-flowing rivers of the Western Ghats (e.g., Periyar, Mandovi)
2. Subsequent Streams
🔵Definition
Subsequent streams develop after consequent streams. They flow along zones of weaker rocks, usually at right angles to the consequent streams.
Features
1.Follow weak rock structures (faults, joints, bedding planes).
2.Develop by differential erosion.
3.Often join the consequent stream at nearly 90°.
4.Common in folded and sedimentary regions.
🔰Examples
Chambal River (tributary of Yamuna)
Ken River
Son River (parts)
3. Obsequent Streams
🟢Definition
Obsequent streams flow opposite to the direction of the original land slope and opposite to the consequent streams.
Features
1.Develop due to headward erosion.
2.Flow opposite to consequent streams.
3.Usually tributaries of subsequent streams.
4.Comparatively smaller streams.
Examples
1.Small tributaries in the Appalachian Mountains (USA)
2.Local examples in the Vindhyan region of India
4. Resequent Streams
🔴Definition
Resequent streams develop later but flow in the same direction as the consequent streams.
Features
1.Younger than subsequent streams.
2.Flow parallel to consequent streams.
3.Form on newly eroded slopes.
4.Usually tributaries of subsequent streams.
🔴Examples
Tributaries in the Appalachian Mountains (USA)
Some tributaries in the Chotanagpur Plateau
🔵🔵Insequent Drainage System
Definition
Insequent drainage develops without any structural or geological control. Streams flow in random directions over homogeneous rocks.
Features
1.No definite relation with rock structure.
2.Develop on uniform rock types.
3.Produce dendritic drainage pattern.
4.Common in granite and basalt regions.
Examples
Parts of the Deccan Plateau
Granite regions of Karnataka
🔴🔴Antecedent Drainage System
Definition
An antecedent drainage system is one in which a river existed before the uplift of mountains and maintained its original course by cutting down through the rising land.
Features
1.Older than the mountain.
2.Cuts deep gorges and canyons.
3.Maintains original flow despite tectonic uplift.
4.Indicates simultaneous uplift and river erosion.
Examples
Indus River
Brahmaputra River
Satluj River
🔰🔰Superimposed Drainage System
Definition
A superimposed drainage system develops on a cover of younger rocks. After erosion removes the cover, the river continues to flow across the underlying older structures, ignoring them.
Features
River course is inherited from an older surface.
Cuts across folds, faults and resistant rocks.
Maintains its original direction.
Produces water gaps and deep valleys.
Examples
Damodar River
Subarnarekha River
Banas River
Parts of the Chambal River
Quick Revision Table
Drainage Type Flow Direction Structural Control Example
Consequent Along original slope No Godavari, Krishna
Subsequent Along weak rocks Yes Chambal, Ken
Obsequent Opposite to original slope Partial Appalachian tributaries
Resequent Same as consequent Partial Chotanagpur tributaries
Insequent Random No Deccan Plateau
Antecedent Original course maintained during uplift No Indus, Brahmaputra, Satluj
Superimposed Ignores underlying structures No (after establishment) Damodar, Subarnarekha, Banas
Drainage Patterns
Definition, Features and Examples (India & West Bengal)
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1. Trellised Pattern
Definition
A Trellised Drainage Pattern is one in which the main river flows through a long valley, while the tributaries join it at nearly right angles (90°).
Features
Develops in folded (Folded) and cuesta regions.
Tributaries join the main river at approximately 90°.
Formed due to alternating bands of hard and soft rocks.
Resembles a garden trellis or lattice.
Examples in India
Folded regions of Kashmir
Eastern Singhbhum region (adjacent to Jharkhand)
Examples in West Bengal
Some rivers of the Darjeeling Himalayas
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2. Dendritic Pattern
Definition
A Dendritic Drainage Pattern is one in which rivers and tributaries branch like the limbs of a tree.
Features
Most common drainage pattern.
Develops over homogeneous rocks.
Little or no structural control.
Tree-like branching network.
Examples in India
Ganga Basin
Brahmaputra Basin
Godavari Basin
Examples in West Bengal
Damodar Basin
Kangsabati Basin
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3. Rectangular Pattern
Definition
A Rectangular Drainage Pattern develops where rivers follow faults and joints, making frequent right-angle (90°) bends.
Features
Develops in faulted and jointed rock regions.
Rivers exhibit right-angle bends.
Forms a rectangular network.
Examples in India
Chotanagpur Plateau
Examples in West Bengal
Some rivers of Purulia District
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4. Radial Pattern
Definition
A Radial Drainage Pattern develops when rivers flow outward in all directions from a central highland or volcanic cone.
Features
Originates from a central elevated area.
Rivers flow outward in all directions.
Common over domes and volcanic cones.
Examples in India
Amarkantak Plateau
Nilgiri Hills
Examples in West Bengal
Some small rivers of the Darjeeling Hills
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5. Annular Pattern
Definition
An Annular Drainage Pattern is one in which rivers flow along circular or ring-shaped courses.
Features
Develops over domes or basins.
Ring-like drainage network.
Formed due to alternating bands of hard and soft rocks.
Examples in India
Parts of the Vindhyan Region
Examples in West Bengal
A true annular drainage pattern is almost absent in West Bengal.
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6. Barbed Pattern
Definition
A Barbed Drainage Pattern is one in which tributaries join the main river from the opposite direction of its flow.
Features
Formed due to River Capture (Stream Piracy).
Tributaries join at reverse angles.
Indicates abnormal drainage development.
Examples in India
Some parts of the Brahmaputra River
Examples in West Bengal
Some reaches of the Teesta River
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7. Pinnate Pattern
Definition
A Pinnate Drainage Pattern is one in which tributaries join the main river like the veins of a feather.
Features
Develops on steep slopes.
Tributaries join the main stream at acute angles.
Feather-like appearance.
Examples in India
Some rivers of the Deccan Plateau
Examples in West Bengal
Some parts of the Kangsabati River
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8. Herringbone Pattern
Definition
A Herringbone Drainage Pattern is one in which tributaries join the main river in a pattern resembling the bones of a fish.
Features
Develops on steep slopes.
Tributaries join the main river almost parallel to one another.
Fish-bone-like appearance.
Examples in India
Some parts of the Himalayas
Examples in West Bengal
Small rivers of the Darjeeling Himalayas
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9. Parallel Pattern
Definition
A Parallel Drainage Pattern is one in which several rivers flow nearly parallel to each other in the same direction.
Features
Develops on long and steep slopes.
Rivers flow almost parallel.
Very few tributaries.
Examples in India
West-flowing rivers of the Western Ghats
Western Coastal Plain
Examples in West Bengal
Himalayan rivers of the Dooars region, such as the Torsa, Jaldhaka, and Raidak, show nearly parallel flow.
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Important Points for Examinations
Most common drainage pattern → Dendritic Pattern
Found in folded regions → Trellised Pattern
Develops in fault and jointed rocks → Rectangular Pattern
Occurs over volcanic cones or domes → Radial Pattern
Found in circular (ring-shaped) structures → Annular Pattern
Formed due to River Capture → Barbed Pattern
Feather-like appearance → Pinnate Pattern
Fish-bone-like appearance → Herringbone Pattern
Parallel flow on steep slopes → Parallel Pattern
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