Unit 3.2: Drainage Patterns & Indian Examples
Indian Geography ā Indian Geography ā PHYSICAL FOUNDATIONS ā PHYSICAL FOUNDATIONS ā Climate & Monsoon | Author: admin | Feb 11, 2026
1. Introduction Unit 3.2 covers drainage patterns ā the spatial arrangement of rivers and their tributaries ā and their prominent examples in India. Drainage patterns are shaped by underlying geology, slope, structure, and lithology. In India, major patterns include dendritic, trellis, radial, and centripetal, each reflecting the region's physiography (Himalayas, Peninsular plateau, plains). This unit links river systems to landforms and helps understand flood-prone areas and water resource distribution.
Significance This is one of the most important units in the syllabus ā it appears in almost every competitive exam as factual recall (patterns, examples) and analytical questions (geological control, flood linkage). In 2026 exams, expect 6ā10 marks in Prelims (match pattern to region, identify examples) and 8ā12 marks in Mains (explain patterns with Indian examples, link to disasters/schemes like flood management). Recent floods (2025ā2026) and river basin studies make it current-affairs heavy. Master this unit for guaranteed high scores across UPSC, SSC, RRB-JE, and State PSC.
2. Chronological/Geological Timeline
- ~50 Ma: Himalayan orogeny begins ? dendritic/trellis patterns form in young folds.
- ~65 Ma: Deccan volcanism ? radial patterns emerge around domes.
- Pleistocene: Glacial/interglacial cycles ? centripetal patterns in basins.
- Holocene: River incision + deposition ? dendritic dominant in plains.
- Ancient: Indus Valley uses dendritic drainage for agriculture.
- Modern: Geological surveys (GSI) map patterns for flood zoning.
- 2020sā2026: Recent flood mapping (NDMA) links patterns to vulnerable zones.
3. Concept Deep Dive Drainage patterns are controlled by geology and structure:
- Dendritic: Tree-like; develops on uniform rock (most common in India).
- Trellis: Rectangular grid; on folded mountains (Himalayas).
- Radial: Outward from dome/peak (central highlands).
- Centripetal: Inward to basin (inland drainage areas). Other types (parallel, rectangular) rare in India. Dendritic dominates plains; trellis in Himalayas; radial in plateaus. (Ref: NCERT Class 11 Fundamentals of Physical Geography Ch. 7 "Landforms & Their Evolution"; Savindra Singh Ch. 11 "Drainage Patterns"; Goh Cheng Leong Ch. on River Valleys; Majid Husain Ch. 3 "Drainage"; Oxford Atlas for pattern maps).
4. Key Terminology Box
- Drainage Pattern: Spatial arrangement of rivers and tributaries.
- Dendritic: Tree-branch pattern on uniform rock.
- Trellis: Rectangular grid on folded/tilted strata.
- Radial: Outward from central high point (dome/volcano).
- Centripetal: Inward to central depression (basin).
- Structural Control: Geology/slope influencing pattern.
- Uniform Lithology: Same rock type ? dendritic.
- Folded Structure: Alternating hard/soft rocks ? trellis.
5. Important Factual Details
| Pattern | Characteristics | Geological Control | Indian Examples |
|---|---|---|---|
| Dendritic | Tree-like, random branching | Uniform rock, gentle slope | Ganga plains, most Peninsular rivers |
| Trellis | Rectangular grid, right-angle bends | Folded/tilted strata | Himalayan rivers (e.g., Ganga tributaries) |
| Radial | Outward from central high | Dome, volcano, upland | Central Highlands (Amarkantak, Mahadeo) |
| Centripetal | Inward to central basin | Depression, inland drainage | Sambhar Lake, Luni basin |
| Parallel | Parallel channels | Steep uniform slope | Western Ghats short streams |
6. Frequently Asked Exam Facts
- Dendritic: Most common pattern in India.
- Trellis: Found in Himalayan folded structures.
- Radial: Around central uplands (e.g., Amarkantak).
- Centripetal: In inland drainage basins (Rajasthan).
- Dendritic forms on uniform lithology.
- Trellis on alternating hard/soft rocks.
- Radial on domes/volcanic cones.
- Centripetal in depressions (e.g., Sambhar).
- Ganga plains: Classic dendritic pattern.
- Himalayas: Trellis due to folds.
7. Comparison Charts/Tables
| Pattern | Geological Control | Slope / Rock Type | Indian Region |
|---|---|---|---|
| Dendritic | Uniform lithology | Gentle, homogeneous rock | Northern Plains, Peninsular plateau |
| Trellis | Folded/tilted strata | Alternating hard/soft layers | Himalayas |
| Radial | Dome or central high | Radial slope from peak | Central Highlands |
| Centripetal | Central depression | Inward slope to basin | Rajasthan (inland drainage) |
8. Spatial Context
- Dendritic: Ganga plains (UP, Bihar), Godavari basin (Maharashtra-AP).
- Trellis: Himalayan tributaries (Ganga, Yamuna in folded zones).
- Radial: Amarkantak (MP, Narmada origin), Mahadeo Hills (MP).
- Centripetal: Sambhar Lake (Rajasthan), Luni basin (Rajasthan-Gujarat).
- Salem/TN relevance: TN rivers (Cauvery, Vaigai) show dendritic pattern in plateau/plains; Salem district near Cauvery basin with dendritic tributaries. Image credit: Wikimedia Commons (CC-BY-SA 4.0) via search, showing map of India drainage patterns with dendritic, trellis, radial examples labeled. Image credit: Wikimedia Commons (Public Domain) via search, showing diagram of major drainage patterns including dendritic, trellis, radial, and centripetal.
9. Flowchart Summary Geological Structure ? Controls Drainage Pattern ? Dendritic (uniform rock ? plains) ? Trellis (folded strata ? Himalayas) ? Radial (dome ? central highlands) ? Centripetal (depression ? inland basins). Image credit: Wikimedia Commons (CC-BY-SA 4.0) via search, showing schematic illustrations of dendritic, trellis, radial, and centripetal drainage patterns.
10. Ultra-Short Exam Capsule
- Dendritic: Most common, uniform rock.
- Trellis: Folded Himalayas.
- Radial: Central domes.
- Centripetal: Inland basins.
- Ganga plains: Dendritic.
- Amarkantak: Radial.
- Sambhar: Centripetal.
TYPE 2: QUICK REVISION & EXAM TRICKS
1. Highlights & Tricky Points
- Key: Dendritic most common; trellis in folds.
- Trap: "All India dendritic?" ā No; trellis in Himalayas, radial in highlands.
- Trap: "Centripetal in plains?" ā No; in depressions (Rajasthan).
- Trap: Confuse radial (outward) with centripetal (inward).
2. Memory Aids/Mnemonics
- Patterns: "Dendritic Trellis Radial Centripetal" ? "DTRC: Dendritic Trees Reach Center".
- Control: "Uniform Dendritic, Folded Trellis, Dome Radial, Basin Centripetal" ? "UFD BRC" (Uniform Fold Dome Basin).
- Examples: "Ganga Dendritic, Himalaya Trellis, Amarkantak Radial, Sambhar Centripetal" ? "GHAR SC".
3. Confusing Concepts
- Dendritic vs Trellis: Dendritic = random branching (uniform rock); Trellis = rectangular grid (folded rock).
- Dendritic: plains; Trellis: mountains.
- Radial vs Centripetal: Radial = outward from high (dome); Centripetal = inward to low (basin).
- Radial: Amarkantak; Centripetal: Sambhar.
TYPE 3: PYQs & EXPECTED QUESTIONS
1. PYQ Vault
- UPSC Prelims 2013: The dendritic drainage pattern is developed in? ? Uniform lithology.
- SSC CGL 2016: Which drainage pattern is found in the Himalayan region? ? Trellis.
- UPSC Prelims 2018: Radial drainage pattern is found around? ? Dome.
- RRB NTPC 2019: Centripetal drainage pattern is seen in? ? Inland basins.
- SSC CGL 2021: The most common drainage pattern in India is? ? Dendritic.
- State PSC (UPPSC 2020): Trellis pattern develops on? ? Folded structures.
- SSC CGL 2019: Radial pattern is associated with? ? Volcanic domes.
- RRB JE 2022: Which pattern shows rivers flowing inward to a basin? ? Centripetal.
- BPSC 2021: Dendritic pattern is seen in? ? Northern plains.
- TNPSC 2022: Drainage pattern in Peninsular plateau is mostly? ? Dendritic.
2. 2026 Expected Questions
- Name the four major drainage patterns in India with examples.
- Which drainage pattern is most common in the Northern Plains?
- Explain the geological conditions for trellis drainage pattern.
- Where is radial drainage pattern typically found in India?
- What is centripetal drainage pattern and give an Indian example?
- How does the dendritic pattern differ from the trellis pattern?