Types of Drainage Patterns with Examples

What Is a Drainage Pattern and What Controls It

What Is a Drainage Pattern?

A drainage pattern is the arrangement of a river and its tributaries in plan view. NCERT defines drainage as the flow of water through well-defined channels and a drainage system as the network of such channels. The shape that network takes is not random. NCERT lists what decides it:

• The geological time period over which the rivers have worked
• The nature and structure of the rocks
• The topography and slope of the land
• The amount of water flowing and how regular that flow is

Because rock and slope decide the shape, geomorphologists read drainage patterns backwards: a trellis of streams points to folded rock, a grid of right-angle bends points to jointed rock, and streams radiating from one spot point to a dome or a peak. All forms of transition occur between parallel, dendritic and trellis patterns.

Types of Drainage Patterns Explained

Dendritic Drainage Pattern: The Tree-Like Network

The dendritic drainage pattern resembles the branches of a tree, and it is the most common drainage pattern of all. The name comes from the Greek for "of or like a tree". Small streams, the twigs, join tributaries, the branches, which join the main river, the trunk.

• Where it forms: On land whose channels follow the general slope of the surface, with V-shaped valleys on rock that is impervious and non-porous.
• Why the shape: With no strong structure to steer them, streams join wherever the slope takes them, at acute angles.
• Indian example: The standard dendritic drainage pattern example in India, as NCERT names it, is the rivers of the northern plain. The Himalayan rivers, NCERT notes, develop a dendritic pattern once they reach the plains.

On a map or a satellite image, a dendritic network is recognised by tributaries that join at acute angles and point roughly downstream, with no preferred direction imposed by the rock. It tells you the ground has no strong structural grain. On the northern plain the pattern sits on deep alluvium, where the Himalayan rivers slow down, meander and, as NCERT notes, shift their courses frequently.

Trellis Drainage Pattern: Right Angles Between Folded Ridges

In a trellis drainage pattern, the primary tributaries flow parallel to one another and the secondary tributaries join them at right angles, like the frame of a garden trellis. It forms where bands of hard and soft rock alternate, as in folded mountains: the main streams run along the valleys of soft rock (strike valleys), and short streams come straight down the steep sides of the ridges between them.

The tributaries are short because each one only has to cross the flank of a single ridge before it reaches the valley floor. The long main streams follow the soft belts because erosion cuts them fastest, and the pattern becomes sharper as erosion deepens the valleys and leaves the hard ridges standing.

• Where it forms: Folded mountains with alternating hard and soft beds.
• Classic example: The best-known trellis drainage pattern example is the Appalachian Mountains of North America; another is the north of Trinidad.
• In India: NCERT groups trellis with radial and rectangular as patterns of the Peninsular rivers, whose courses are superimposed and rejuvenated.

Rectangular Drainage Pattern: Jointed Rock and Right-Angle Bends

A rectangular drainage pattern develops on rock of roughly uniform strength that is cut by two sets of joints at about right angles. The joints are weaker than the rock around them, so erosion opens them first and streams settle along them. The result is streams made of straight segments with sharp right-angle bends, with tributaries also joining at right angles.

The Arun River in Nepal is the example usually cited. A related form, angular drainage, develops where joints and faults cross at angles other than 90 degrees, so the bends are sharp but not square.

The way to tell it on a map is the repeated square turn. A stream runs straight, bends through a right angle, runs straight again and bends again, because it is following one joint and then switching to the crossing joint. The Arun is also the main stream of the Kosi, which NCERT describes as an antecedent river rising north of Mount Everest in Tibet: one river can show a rectangular pattern locally and an antecedent course overall.

Radial Drainage Pattern: Streams Flowing Out from a High Point

In a radial drainage pattern, streams flow outward in all directions from a central high point, like the spokes of a wheel. Volcanoes and domes are its typical settings, because every slope falls away from the centre. The best radial drainage pattern example in India is Amarkantak.

• Amarkantak: NCERT’s example. Amarkantak is the meeting point of the Vindhya and Satpura ranges, with the Maikal Hills at the centre. The Narmada rises on the western flank of the Amarkantak plateau at about 1,057 m and flows west; the Son rises on the same plateau and flows north-east to join the Ganga near Arrah, west of Patna.
• Ramgarh crater: An impact crater in Baran district of Rajasthan, 3.2 km across and rising 150 to 200 m above the plain, named with Amarkantak as India’s most typical radial pattern. The Geological Survey of India has made it a National Geological Monument.

Amarkantak lies in Anuppur district of Madhya Pradesh. Because its rivers leave the same high ground in opposite directions, the Narmada reaching the Arabian Sea and the Son the Bay of Bengal by way of the Ganga, one plateau feeds two seas, which is the clearest sign of a radial centre.

Centripetal Drainage Pattern: Streams Flowing In to a Basin

A centripetal drainage pattern is the reverse of radial: streams from all sides flow in towards a lake or a depression. Because the water collects inland rather than reaching the sea, it is also called inland drainage.

Loktak Lake in Manipur shows the idea. The Manipur River and the Nambul, Yangoi, Nambol and Thongjaorok streams flow into its northern zone, the Khuga and Kangshoibi reach its southern zone, and the lake drains out through the Ithai barrage. Streams converging from around a valley on one lake fit NCERT's definition of centripetal drainage: rivers discharging their waters from all directions into a lake or depression.

The lake covers about 236 square kilometres, and its direct catchment at the Ithai barrage outlet is about 980 square kilometres, much of it under paddy fields, settlement and forest.

• Phumdis: Loktak is known for its phumdis, floating masses of vegetation, soil and organic matter.
• Keibul Lamjao: The largest phumdi carries Keibul Lamjao, the only floating national park in the world and the last natural refuge of the sangai deer.

Parallel Drainage Pattern: Straight Streams on a Steady Slope

In a parallel drainage pattern, streams run swift and straight, side by side, with very few tributaries, all flowing in the same direction. It forms on long, uniform slopes and on elongated landforms such as bands of resistant rock; sometimes it marks a major fault. The rivers flowing south-east from the Aberdare Mountains in Kenya and many rivers of Myanmar are the textbook cases.

The western slope of the Western Ghats fits this description. Of Kerala's 44 rivers, 41 flow west to the Arabian Sea, and NCERT notes that the rivers flowing to the Arabian Sea have short courses. Only three of Kerala's rivers flow east: the Kabini, the Bhavani and the Pambar; the Kabini and the Bhavani join the Kaveri system.

NCERT names several of these short west-flowing rivers:

• Mandovi and Zuari: The two important rivers of Goa.
• Bharathapuzha: The longest river of Kerala, also called the Ponnani, rising near the Annamalai hills and draining about 5,397 square kilometres.
• Periyar: The second largest river of Kerala, with a catchment of about 5,243 square kilometres.
• Pamba: Flows 177 km before falling into Vembanad lake.

Annular and Deranged Drainage Patterns

Two less common patterns complete the set, and both are asked about in definition questions:

• Annular drainage pattern: Streams curve in rings along belts of weak rock around a maturely eroded dome or basin, where erosion has exposed rings of rock of different hardness. The Red Valley, which nearly encircles the Black Hills dome of South Dakota, is the standard example. Impact craters and mud diapirs can also produce it.
• Deranged drainage: A pattern with no coherent order, full of lakes and swamps, found where glaciers scraped the land bare (the Canadian Shield) or where limestone lets surface streams vanish into caves. The basins are young and still sorting themselves out.

Accordant and Discordant Drainage: Antecedent and Superimposed Rivers

Every pattern above is accordant, meaning it fits the rock and relief it flows over. Some rivers do not fit, and their patterns are called discordant. There are two ways a river ends up out of step with the land beneath it:

• Antecedent river: The river existed before the land rose and kept its course by cutting down as fast as the uplift, carving a steep gorge through the rising ridge; this is antecedent drainage. It can keep a dendritic pattern over ground that would otherwise produce trellis drainage.
• Superimposed river: The river formed on younger, horizontal beds lying over folded or faulted rock. Once it cut through the top beds, it kept its course and carried it down into the older rocks below, cutting gorges through their resistant bands.

The Himalayan rivers are India's standard antecedent examples. The Indus, Brahmaputra, Sutlej, Kosi and Subansiri rose on the Tibetan side before the ranges were uplifted and now cross them through deep gorges. NCERT describes the Sutlej, which passes through the Shipki La, the Kosi and the Subansiri as antecedent rivers, and calls the Peninsular rivers superimposed and rejuvenated.

Comparing Drainage Patterns: Differences Students Confuse

Difference Between Radial and Centripetal Drainage Pattern

The difference between radial and centripetal drainage is the direction of flow: radial streams flow out from a high point, while centripetal streams flow in to a low point. The two look alike on a map, so check what sits at the centre.

Difference Between Trellis and Rectangular Drainage Pattern

Both patterns have tributaries meeting at right angles, so the difference lies in the rock beneath: trellis drainage forms on folded rock with alternating hard and soft bands, while rectangular drainage forms on rock of uniform strength broken by joints that cross at right angles.

The table below sets all eight patterns side by side for revision.

Reading Drainage Patterns on Toposheets and Satellite Images

NCERT's practical geography treats drainage as one of the first things to read on a topographical sheet: the important rivers and their tributaries, the type and extent of the valleys they form, and the type of drainage pattern, such as dendritic, radial, ring, trellis or internal. The pattern is a quick guide to what lies beneath:

• Acute-angle junctions, no preferred direction: Dendritic; uniform ground with no strong structure.
• Long parallel streams with short right-angle feeders: Trellis; folded hard and soft beds.
• Square bends and right-angle junctions: Rectangular; jointed rock.
• Streams leaving or entering one point: Radial on a high, centripetal in a basin.
• Rings of streams: Annular; an eroded dome or basin.
• Lakes and streams with no order: Deranged; glaciated or limestone ground.

Drainage Patterns in India: Examples on the Map

Indian Examples: Amarkantak, Narmada Rift, Loktak and the Western Ghats

NCERT sums up the contrast between India's two river systems in one line each. The Himalayan rivers are antecedent and consequent and develop a dendritic pattern in the plains. The Peninsular rivers are superimposed and rejuvenated, giving trellis, radial and rectangular patterns.

Most Peninsular rivers flow east because the Peninsular block tilted slightly from north-west to south-east, which turned the whole drainage system towards the Bay of Bengal. The Narmada and the Tapi are the exceptions: they flow west in trough faults (rift valleys) that opened when the northern flank of the Peninsula subsided during the rise of the Himalayas. The Narmada runs between the Satpura to the south and the Vindhyan range to the north for about 1,312 km to the Gulf of Khambhat. The Tapi rises at Multai in Betul district of Madhya Pradesh.

Himalayan and Peninsular Rivers: Drainage Patterns Compared

The two great river systems of India show different patterns because they differ in age, source and setting. NCERT compares them point by point:

The table explains the map. Young Himalayan rivers flowing onto a vast plain of soft alluvium spread into dendritic networks, while old Peninsular rivers working across hard, faulted and jointed rocks show the structural patterns.

Why West-Flowing Rivers Form Estuaries, Not Deltas

The west-flowing rivers of the Peninsula form estuaries, not deltas, and the reasons lie in their valleys and their coast. A delta grows where a river carrying sediment reaches still water, spreads out, slows down and drops its load. Four conditions on the west coast work against that:

1. Rift valleys: The Narmada and the Tapi flow in trough faults and fill the original cracks with their own debris, so NCERT notes a lack of alluvial and deltaic deposits in them. Rift valley rivers form estuaries; the Narmada meets the sea south of Bharuch in a broad estuary about 27 km long.
2. Short courses: The rivers flowing to the Arabian Sea have short courses and small basins.
3. A narrow, submerged coast: The western coastal plain is narrow and is an example of a submerged coastal plain; NCERT states that the rivers crossing it do not form any delta.
4. Against the east coast: The eastern coastal plain is broad and emergent, with a continental shelf extending up to 500 km, and there the Mahanadi, Godavari, Krishna and Kaveri build well-developed deltas.

Drainage Patterns in UPSC Previous Year Questions

UPSC Questions on Drainage Patterns and Indian Rivers

UPSC asks about drainage patterns through Indian examples rather than bare definitions. Knowing where each river rises, which way it flows and why answers nearly every question set so far.

In the 2023 question, the other two statements also fail. The Biligirirangan Hills are where the Eastern Ghats begin and meet the Western Ghats, not part of the Satpura Range, and the Seshachalam Hills are part of the Eastern Ghats in Andhra Pradesh, not the southernmost part of the Western Ghats.

Sources

• Wikipedia: Drainage system (geomorphology)
• Wikipedia: Amarkantak
• Wikipedia: Narmada River
• Wikipedia: Son River
• Wikipedia: Tapti River
• Wikipedia: Mahi River
• Wikipedia: Mahanadi
• Wikipedia: Loktak Lake
• Wikipedia: List of rivers of Kerala
• Wikipedia: Kabini River
• Wikipedia: Bhavani River
• Wikipedia: Ramgarh crater
• Wikipedia: River delta
• Wikipedia: Biligirirangan Hills
• Wikipedia: Seshachalam Hills
• NCERT: India Physical Environment (Class XI), Drainage System
• NCERT: Practical Work in Geography Part I (Class XI)
• Geological Survey of India
• Central Water Commission
• India-WRIS: Water Resources Information System
• Bhuvan, National Remote Sensing Centre