Drainage Patterns, Classification and Himalayan versus Peninsular Drainage (Class 11 Geography, India: Physical Environment, Chapter 3)
Updated 17 October 2026 · Fact-checked
Drainage is the flow of water through well-defined channels. Indian drainage is classified by sea (Bay of Bengal about 77 per cent, Arabian Sea about 23 per cent), by size (major, medium, minor) and by origin (Himalayan and Peninsular). Himalayan rivers are perennial and young; Peninsular rivers are older, with fixed courses, no meanders and non-perennial flow.
Notice how each pattern looks: tree branches, spokes outward from a hill, right-angle ladders, and rivers flowing inward to a lake.
Illustration drawn for QuestionBuddy.
Understand Drainage Patterns, Classification of Indian Drainage and Himalayan versus Peninsular Rivers
Why this topic matters. The Himalayan-versus-Peninsular comparison, drainage patterns and the dismembering of the Indo-Brahma river are asked every year.
1. Terms. A network of well-defined channels is a drainage system. The catchment area is the area from which a river collects water. The drainage basin is the area drained by a river and its tributaries. The watershed is the boundary separating one basin from another; small catchments are also called watersheds, large ones river basins. Basins are units of unity, so they are good planning regions.
2. Patterns. Dendritic: like tree branches (rivers of the northern plain). Radial: rivers rise on a hill and flow in all directions (rivers from the Amarkantak range). Trellis: primary tributaries are parallel and secondary ones join at right angles. Centripetal: rivers flow from all directions into a lake or depression. The pattern depends on geological period, rock type and structure, topography, slope, water volume and periodicity.
3. Classification. By sea: the Bay of Bengal group (about 77 per cent of the drainage area) and the Arabian Sea group (about 23 per cent), separated by the Delhi ridge, the Aravalis and the Sahyadris. By size: major (above 20,000 sq km, 14 basins), medium (2,000 to 20,000 sq km, 44 basins) and minor (below 2,000 sq km). By origin and nature: Himalayan and Peninsular.
4. Himalayan drainage. Perennial, fed by snow-melt and rain. In the mountains: gorges, V-shaped valleys, rapids and waterfalls. In the plains: meanders, oxbow lakes, floodplains, braided channels, deltas and frequent shifts of course; the Kosi is the sorrow of Bihar.
5. Evolution of the Himalayan drainage. One view: a mighty Shiwalik or Indo-Brahma river once flowed along the whole Himalaya from Assam to Punjab and Sind, discharging into the Gulf of Sind in the Miocene. It was dismembered into the Indus, the Ganga and the Brahmaputra systems by the Pleistocene upheaval in the western Himalaya (uplift of the Potwar Plateau, the Delhi ridge, forming the Indus-Ganga divide) and the down-thrusting of the Malda gap, which diverted the Ganga and Brahmaputra to the Bay of Bengal.
6. Peninsular drainage. Older, with broad, graded, shallow valleys and mature rivers. The Western Ghats form the water divide. Most rivers flow west to east except the Narmada and Tapi in rift valleys. Fixed courses, no meanders, non-perennial. Three events shaped it: subsidence of the western flank in the early Tertiary, trough faulting during the Himalayan upheaval (Narmada and Tapi) and a slight tilt of the block from north-west to south-east.
Drainage Patterns, Classification of Indian Drainage and Himalayan versus Peninsular Rivers: key facts
- Drainage terms
Catchment area from which a river collects water Basin area drained by a river and tributaries Watershed boundary between basins - Basins are planning regions.
- Patterns
Dendritic tree-like Radial outward from a hill Trellis parallel tributaries with right-angle joins Centripetal into a lake - Four patterns.
- By sea
Bay of Bengal about 77 per cent Arabian Sea about 23 per cent Divide Delhi ridge, Aravalis, Sahyadris - Share of drainage area.
- By size
Major above 20,000 sq km, 14 basins Medium 2,000 to 20,000 sq km, 44 basins Minor below 2,000 sq km - Catchment size.
How to answer Drainage Patterns, Classification of Indian Drainage and Himalayan versus Peninsular Rivers questions
Comparison questions use two columns and equal points.
- 1Choose 4 points: source and flow, valley form, course, age and character.
- 2Write the Himalayan feature, then the matching Peninsular feature on the same row.
- 3Add one example river for each.
- 4End with the reason for the difference (young versus old, snow-fed versus rain-fed).
Drainage Patterns, Classification of Indian Drainage and Himalayan versus Peninsular Rivers in real life
The idea, met in an everyday situation. Answer the question in your own words, then compare with the model answer. The one-line hook is what to remember.
Tree and river map
Suppose a map of a plain shows a main river with many branches joining it like twigs on a branch.
Which pattern is this?
Try it first, then show the solutionSolution
- Branches like those of a tree.
- This is the dendritic pattern, as in the northern plain.
Answer: Dendritic pattern.
Memory hook: Tree equals dendritic.
Planning a village project
Suppose a district plans soil conservation for the whole area drained by a stream and its feeders.
Which drainage unit is the planning region?
Try it first, then show the solutionSolution
- The area drained by the stream and its tributaries is the basin.
- A change in one part affects the whole, so the basin is a unit.
Answer: The drainage basin or watershed.
Memory hook: Basin means one unit.
Tricks to remember Drainage Patterns, Classification of Indian Drainage and Himalayan versus Peninsular Rivers
Short memory aids. Say each one aloud once, then use it on a question the same day.
DRTC
Dendritic, Radial, Trellis, Centripetal
Use it when: Patterns.
77-23
Bay of Bengal 77, Arabian Sea 23
Use it when: Share of drainage.
Young fast, old fixed
Himalayan rivers shift and meander; Peninsular rivers have fixed courses
Use it when: Comparison.
Drainage Patterns, Classification of Indian Drainage and Himalayan versus Peninsular Rivers: solved examples
Ordered from board level to HOTS. Try each one before you open the solution.
Example 1: Watershed · 1 mark · MCQBoard level
The boundary line separating one drainage basin from another is called a:
(A) catchment
(B) delta
(C) watershed
(D) tributary
Try it first, then show the solutionSolution
- The dividing boundary is the watershed (1 mark).
Answer: (C)
Example 2: Radial pattern · 2 marks · Very short answerBoard level
What is a radial drainage pattern? Name the area in the chapter that shows it. (2 marks)
Try it first, then show the solutionSolution
- Rivers rise on a hill and flow in all directions (1 mark).
- Rivers from the Amarkantak range (1 mark).
Answer: In a radial pattern rivers rise on a hill and flow outward in all directions, as the rivers from the Amarkantak range do.
Example 3: Himalayan versus Peninsular · 3 marks · Short answerHarder board level
Contrast the Himalayan and Peninsular rivers on perennial flow, course behaviour and valley form. (3 marks)
Try it first, then show the solutionSolution
- Himalayan rivers are perennial; Peninsular are non-perennial (1 mark).
- Himalayan have meanders and shift course; Peninsular have fixed courses and no meanders (1 mark).
- Himalayan rivers are young and form gorges and deltas; Peninsular have broad, graded, shallow valleys (1 mark).
Answer: Himalayan rivers are perennial, fed by snow and rain, whereas Peninsular rivers are non-perennial. Himalayan rivers meander and shift their courses in the plains, but Peninsular rivers have fixed courses without meanders. Himalayan rivers are younger and cut gorges in the mountains, while Peninsular rivers are older with broad, graded, shallow valleys.
Example 4: Assertion and reason: Narmada · 1 mark · Assertion-reasonHarder board level
Assertion (A): The Narmada and Tapi build no large deltas.
Reason (R): They flow in trough faults and fill the cracks with detritus, so they lack alluvial and deltaic deposits.
(A) Both true, R explains A
(B) Both true, R does not explain A
(C) A true, R false
(D) A false, R true
Try it first, then show the solutionSolution
- The chapter gives trough faulting and the filling of cracks with detritus as the reason for the lack of deltaic deposits (1 mark).
Answer: (A)
Example 5: HOTS: dismembered river · 5 marks · Long answerHOTS / competency
A student claims that the Indus, Ganga and Brahmaputra were once part of one long river. Present the evidence and the events that split it, and state that this is one view among several. (5 marks)
Try it first, then show the solutionSolution
- A mighty Shiwalik or Indo-Brahma river flowed from Assam to Punjab and Sind (1 mark).
- Evidence: continuity of the Shiwalik and its lacustrine, alluvial deposits (1 mark).
- Pleistocene upheaval in the western Himalaya, uplift of the Potwar Plateau made the Indus-Ganga divide (1 mark).
- Down-thrusting of the Malda gap diverted the Ganga and Brahmaputra to the Bay of Bengal (1 mark).
- Opinions differ on the evolution; this is one view (1 mark).
Answer: According to one view, a mighty Indo-Brahma (Shiwalik) river flowed from Assam to Punjab and Sind into the Gulf of Sind in the Miocene. The remarkable continuity of the Shiwalik and its lacustrine, alluvial deposits are cited as evidence. The Pleistocene upheaval in the western Himalaya raised the Potwar Plateau (the Delhi ridge) as the Indus-Ganga divide, and the down-thrusting of the Malda gap diverted the Ganga and Brahmaputra to the Bay of Bengal, so the river was dismembered into three systems. Scholars hold differing opinions on this evolution.
Where students lose marks in Drainage Patterns, Classification of Indian Drainage and Himalayan versus Peninsular Rivers
The slips examiners see most often, and what to write instead.
Mistake: Saying Himalayan rivers are non-perennial
Mixing the two systems.
Wrong working
Himalayan rivers dry up in summer.
Right working
Himalayan rivers are perennial, fed by snow-melt and rain.
Do this: Tie perennial to snow.
Usually costs: 1 mark.
Mistake: Calling the watershed the river basin
Terms used loosely.
Wrong working
Watershed is the area drained by a river.
Right working
Watershed is the dividing boundary (also small catchments); the basin is the drained area.
Do this: Define each separately.
Usually costs: 1 mark.
Mistake: Swapping the 77 and 23 figures
Number memory.
Wrong working
Arabian Sea has 77 per cent.
Right working
Bay of Bengal about 77, Arabian Sea about 23.
Do this: Link the larger group with the bigger rivers.
Usually costs: 1 mark.
Exam tips
- In a comparison use a two-column table with matching rows.
- Quote the figures 77, 23, 14 and 44 correctly.
- State that the evolution of Himalayan drainage is one view among several opinions.
Practice questions on Drainage Patterns, Classification of Indian Drainage and Himalayan versus Peninsular Rivers
Write each answer on paper first. Open the hint only if you are stuck, and the answer only when you have finished.
Q1 · 1 mark · MCQBoard level
The Arabian Sea group of rivers drains roughly what share of the country?
(A) 23 per cent
(B) 50 per cent
(C) 77 per cent
(D) 90 per centHint
Smaller share.
Answer
(A)
Q2 · 2 marks · Very short answerBoard level
Name the dividing features between the Bay of Bengal and Arabian Sea drainage. (2 marks)
Hint
Three features.
Answer
The Delhi ridge, the Aravalis and the Sahyadris separate the two groups.
Q3 · 3 marks · Short answerHarder board level
Explain why basins and watersheds make good planning regions. (3 marks)
Hint
Unity.
Answer
A drainage basin or watershed is a unit in which a change in one part affects the whole. Its soil, water and land use are linked, so planning can be done for it as a micro, meso or macro region.
Q4 · 3 marks · Short answerHarder board level
Which three happenings in geological time gave the Peninsular rivers their present layout, and what did each do? (3 marks)
Hint
West flank, trough faulting, tilt.
Answer
The western flank of the Peninsula subsided below the sea in the early Tertiary, upsetting the symmetry of rivers around the original watershed. The Himalayan upheaval caused trough faulting in the north, in which the Narmada and Tapi flow. A slight tilt of the block from north-west to south-east oriented the drainage towards the Bay of Bengal.
Q5 · 4 marks · Short answerHOTS / competency
The Kosi regularly shifts its course in Bihar. Explain the cause with reference to the character of Himalayan rivers, and say why Peninsular rivers rarely do this. (4 marks)
Hint
Sediment.
Answer
The Kosi brings a huge load of sediment from its upper reaches and deposits it in the plains, which blocks its channel and makes it shift course; Himalayan rivers show frequent shifts and meanders in the plains. Peninsular rivers are older, flow in broad, graded valleys and have fixed courses without meanders.
Test your recall
Answer in your head or on paper first, then open the card. Pulling an answer out of memory makes it stick far better than re-reading.
1.Name the four drainage patterns.Show answer
Dendritic, radial, trellis and centripetal.
2.How many major river basins are there?Show answer
14.
3.Which rivers flow in rift valleys?Show answer
Narmada and Tapi.
4.Which river is the sorrow of Bihar?Show answer
Kosi.
Drainage Patterns, Classification of Indian Drainage and Himalayan versus Peninsular Rivers: frequently asked questions
What is a delta?
A depositional plain at the mouth of a river, as in Himalayan rivers of the plains.
What is the Malda gap?
The gap between the Rajmahal hills and the Meghalaya plateau, down-thrust in the mid-Pleistocene.
Are the Chambal and Betwa Himalayan rivers?
No; they are Peninsular in origin but belong to the Ganga system.