Drainage System Of India

Drainage means the flow of water through well-defined channels.

The network of such channels is called a drainage system.

A drainage system is shaped by many factors, such as geological age, rock structure, topography, slope, water volume and the regularity of flow.

Some rivers are perennial, meaning they carry water throughout the year.

Some rivers are ephemeral, meaning they carry water mainly during the rainy season and remain dry for the rest of the year.

Catchment Area, Drainage Basin And Watershed

A river collects water from a specific area.

This area is called its catchment area.

An area drained by a river and its tributaries is called a drainage basin.

The boundary line separating one drainage basin from another is called a watershed.

Difference Between River Basin And Watershed

Basis	River Basin	Watershed
Meaning	Area drained by a river and its tributaries	Boundary or smaller drainage unit separating basins
Size	Larger	Smaller
Use	Used for large rivers	Used for small rivulets and rills
Example	Ganga Basin, Brahmaputra Basin	Small local drainage divide

Factors Affecting Drainage Pattern

Drainage pattern depends on:

• Nature and structure of rocks.
• Topography.
• Slope.
• Amount of water.
• Geological history.
• Periodicity of river flow.

Genetic Classification Of Drainage System

On the basis of origin and relation with original slope, underlying rocks and structures, streams are divided into two major groups:

• Sequent Drainage System
• Insequent Drainage System

Sequent Drainage System

Streams that follow the regional slope and adjust to local geological structure are called sequent rivers.

They are further divided into:

• Consequent streams.
• Subsequent streams.
• Obsequent streams.
• Resequent streams.

Consequent Stream

A consequent stream is also called a dip stream.

It follows the original slope of the land over which it developed.

Example

The Godavari and Kaveri rivers of Peninsular India are examples of consequent streams because they follow the normal slope of land and drain into the Bay of Bengal.

Subsequent Stream

A subsequent stream originates after the master consequent stream.

It follows the axis of anticlines or ridges and the strike of rock beds.

Example

The Asan River, a tributary of the Yamuna, and the Song River, a tributary of the Ganga in Dehradun Valley, are examples of subsequent streams.

Here, the Yamuna and Ganga are master consequent rivers.

Obsequent Stream

An obsequent stream flows in the opposite direction to the consequent stream.

It often flows against the direction of dip.

Example

Several streams from the northern slopes of the Mahabharat Range of the Lesser Himalayas flow northward and join the Kosi.

These are called obsequent streams because they flow opposite to master consequent rivers like the Ganga and Yamuna.

Resequent Stream

A resequent stream is a tributary stream that flows in the same direction as the master consequent stream.

It originates much later than the master consequent stream.

Insequent Drainage System

Streams that do not follow the regional slope and drain across geological structures are called insequent or inconsequent streams.

The best examples of insequent drainage are:

• Superimposed streams.
• Antecedent streams.

Superimposed Stream

A superimposed stream is a river that originally developed on an upper geological formation but later continued to flow across an older structure below it.

It keeps the course inherited from its earlier form even when the underlying rock structure changes.

Example

The Son River flowing across the Khainjua ridges in the southern part of the Rewa Plateau in Madhya Pradesh is an example of a superimposed river.

Antecedent Stream

An antecedent stream existed before the upliftment of the land surface.

It maintains its original course even after upliftment of mountains or other landforms.

Examples

The Indus, Sutlej and Brahmaputra are examples of antecedent rivers because they cut transverse gorges across the Himalayan mountains.

As the Himalayas rose, these rivers continued to cut down their valleys and maintained their original courses.

Types Of Drainage Patterns

Drainage pattern refers to the shape formed by a river and its tributaries.

The chapter mentions the following important drainage patterns:

• Dendritic drainage pattern.
• Parallel drainage pattern.
• Trellis drainage pattern.
• Rectangular drainage pattern.
• Radial drainage pattern.
• Centripetal drainage pattern.
• Pinnate drainage pattern.
• Annular drainage pattern.

Dendritic Drainage Pattern

The dendritic drainage pattern is the most common drainage pattern.

It looks like the branching pattern of tree roots.

It develops where the underlying rock can be eroded easily and equally in all directions.

Tributaries join the main stream at acute angles.

Example

Rivers of the northern plains such as the Indus, Ganga and Brahmaputra show dendritic drainage.

Parallel Drainage Pattern

A parallel drainage pattern develops in areas with a pronounced slope and parallel elongated landforms.

Streams flow almost parallel to each other.

Example

Rivers originating in the Western Ghats, such as the Godavari and Krishna, show this pattern.

Trellis Drainage Pattern

A trellis drainage pattern develops in areas with parallel elongated landforms.

The main river flows along a valley and tributaries join it almost at right angles.

Example

Rivers in the upper Himalayan region show trellis drainage.

Rectangular Drainage Pattern

A rectangular drainage pattern develops in regions that have undergone faulting.

Streams follow zones of weak rock and joints.

Tributaries bend sharply and join the main stream at high angles.

Example

Streams found in the Vindhya Mountain Range, such as Chambal, Betwa and Ken, show rectangular features.

Radial Drainage Pattern

A radial drainage pattern develops from a central elevated point.

Rivers flow outward in all directions from a hill or dome-like structure.

Example

Rivers originating from the Amarkantak Range, such as the Narmada and Son, show radial drainage.

Centripetal Drainage Pattern

A centripetal drainage pattern is opposite of radial drainage.

Here, streams flow towards a central depression.

During wetter seasons, these streams may feed temporary lakes.

In dry seasons, such lakes may evaporate and leave behind salt flats.

Example

Loktak Lake in Manipur is mentioned as an example.

Pinnate Drainage Pattern

A pinnate drainage pattern resembles the veins of a leaf.

It has a main river with smaller tributaries joining at acute angles.

It develops in regions with uniform rock structure and little faulting or jointing.

Examples

The Godavari, Mahanadi and Narmada river systems show pinnate features.

Annular Drainage Pattern

An annular drainage pattern is a ring-like or circular stream system.

It forms on dome-shaped structures or eroded volcanic craters.

Streams flow in concentric circles around a central uplift.

Example

The Nilgiri Hills region of Tamil Nadu and Kerala shows an annular drainage pattern.

Drainage Basins Of India By Size

On the basis of watershed size, India’s drainage basins are grouped into three categories:

• Major river basins.
• Medium river basins.
• Minor river basins.

Major River Basins

Major river basins have more than 20,000 square Km of catchment area.

They include 14 drainage basins such as:

• Ganga
• Brahmaputra
• Krishna
• Tapi
• Narmada
• Mahi
• Pennar
• Sabarmati
• Barak

Medium River Basins

Medium river basins have catchment areas between 2,000 and 20,000 square Km.

They include about 44 river basins, such as:

• Kalindi
• Periyar
• Meghna

Minor River Basins

Minor river basins have catchment areas of less than 2,000 square Km.

Many of these rivers flow in low-rainfall areas.

Classification Of Indian Drainage

On the basis of origin, nature and characteristics, Indian drainage is divided into two major systems:

• Himalayan Drainage System
• Peninsular Drainage System

Himalayan Drainage System

The Himalayan drainage system has evolved through a long geological history.

The important rivers of this system are:

• Indus
• Ganga
• Brahmaputra

These rivers are perennial because they are fed by both:

• Melting snow.
• Rainfall.

Features Of Himalayan Rivers

In their mountainous courses, Himalayan rivers form:

• Deep gorges.
• V-shaped valleys.
• Rapids.
• Waterfalls.

When they enter the plains, they form depositional features such as:

• Flat valleys.
• Ox-bow lakes.
• Flood plains.

Evolution Of Himalayan Drainage

Geologists believe that a mighty river called Shiwalik or Indo-Brahma once flowed along the entire length of the Himalayas.

It flowed from Assam to Punjab and then towards Sind, finally draining into the Gulf of Sind near lower Punjab.

This river existed during the Miocene period, about 5 to 24 million years ago.

Later, the Indo-Brahma river system was broken into three major drainage systems:

• Brahmaputra system in the eastern part.
• Ganga system in the central part.
• Indus system in the western part.

Indus River System

The Indus River System is one of the major Himalayan drainage systems.

The Indus and some of its important tributaries are antecedent rivers.

They existed before the rise of the Himalayas and continued to cut deep gorges as the mountains rose.

Major Tributaries Of Indus

The five important tributaries of the Indus are:

• Jhelum
• Chenab
• Ravi
• Beas
• Sutlej

These rivers form the major western Himalayan drainage system.

Importance

The Indus system is important because it drains the north-western part of the Indian subcontinent and is closely linked with the Punjab plains.

Ganga River System

The Ganga River System is the central part of the Himalayan drainage system.

The Ganga is formed by the meeting of the Bhagirathi and Alaknanda rivers at Devprayag.

Important Tributaries

Important tributaries associated with the Ganga system include:

• Yamuna
• Ramganga
• Gomti
• Ghaghara
• Gandak
• Kosi
• Son

The Ganga system forms one of the most fertile and densely populated river basins in India.

Important Confluences

• Bhagirathi and Alaknanda meet at Devprayag to form the Ganga.
• Mandakini meets Alaknanda at Rudraprayag.

Delta

The Ganga and Brahmaputra together form the Sundarban Delta, one of the largest deltaic regions in the world.

The chapter also mentions the Bengal Delta and its sub-division called the Moribund Delta.

Brahmaputra River System

The Brahmaputra is one of the largest rivers in the world.

It originates from the Chemayungdung Glacier of the Kailash Range near Mansarovar Lake.

In Tibet, it is known as the Tsangpo.

Course Of Brahmaputra

The Brahmaputra flows through Tibet and then takes a sharp bend near Namcha Barwa.

After carving a deep gorge in the Central Himalayas, it enters India.

It emerges from the foothills as the Siang or Dihang.

The Dibang is a major left-bank tributary of the Brahmaputra in Arunachal Pradesh.

Near Sadiya, the Dibang joins the Lohit, and from there the river is called the Brahmaputra.

It enters India west of Sadiya town in Arunachal Pradesh.

Brahmaputra In Assam And Bangladesh

The Brahmaputra flows for about 750 Km through the Assam Valley.

It receives many tributaries during this journey.

In Bangladesh, the Tista joins it on the right bank.

From there, the river is known as the Yamuna.

It finally merges with the Padma, which drains into the Bay of Bengal.

Tributaries Of Brahmaputra

Important left-bank tributaries:

• Burhi Dihing
• Dhansari South

Important right-bank tributaries:

• Subansiri
• Kameng
• Manas
• Sankosh

Floods And Channel Shifting

The Brahmaputra is known for:

• Floods.
• Channel shifting.
• Bank erosion.

This happens because its tributaries are large and bring huge amounts of sediments due to heavy rainfall in the catchment area.

Peninsular Drainage System

The Peninsular drainage system is older than the Himalayan drainage system.

This is clear from its broad, shallow and mature river valleys.

The rivers have largely graded profiles.

Main Features Of Peninsular Rivers

• They are older than Himalayan rivers.
• They have broad and shallow valleys.
• They are mostly seasonal or non-perennial.
• They usually have fixed courses.
• They generally lack large meanders.
• Most rivers flow from west to east.
• Narmada and Tapi are exceptions because they flow westward through rift valleys.

Western Ghats As Water Divide

The Western Ghats run close to the western coast.

They act as a major water divide.

Most major Peninsular rivers flow eastward and drain into the Bay of Bengal.

Small west-flowing rivers drain into the Arabian Sea.

Rivers Joining The Ganga System

Some rivers originating in the northern part of the Peninsula join the Ganga system.

Important examples include:

• Chambal
• Sind
• Betwa
• Ken
• Son

Evolution Of Peninsular Drainage

Three major geological events shaped the present Peninsular drainage system.

Submergence Of Western Flank

The western flank of the Peninsula subsided and was submerged below the sea during the early Tertiary period.

This disturbed the symmetrical drainage pattern on both sides of the original watershed.

Tilting Of Peninsular Block

The Peninsular block tilted slightly from the north-west towards the south-east.

This gave most Peninsular rivers their eastward orientation towards the Bay of Bengal.

Trough Faulting

During the uplift of the Himalayas, the northern flank of the Peninsular block experienced subsidence and trough faulting.

The Narmada and Tapi rivers flow through these trough faults.

This is why these rivers lack large alluvial and deltaic deposits.

Major Peninsular River Systems

The major Peninsular river systems include:

• Mahanadi
• Godavari
• Krishna
• Kaveri
• Narmada
• Tapi

Mahanadi River System

The Mahanadi rises near Sihawa in the Raipur district of Chhattisgarh.

It flows through Odisha and drains into the Bay of Bengal.

Important Facts

• Length – 851 Km.
• Catchment area – 1.42 lakh square Km.
• About 53 per cent of its drainage basin lies in Madhya Pradesh and Chhattisgarh.
• About 47 per cent lies in Odisha.
• Some navigation is carried on in its lower course.
• Hirakud Dam is situated on the Mahanadi in Odisha.

Godavari River System

The Godavari is the largest Peninsular river system.

It is also called the Dakshin Ganga.

It rises in the Nasik district of Maharashtra and drains into the Bay of Bengal.

Important Facts

• Length – 1,465 Km.
• Catchment area – 3.13 lakh square Km.
• About 49 per cent of the basin lies in Maharashtra.
• About 20 per cent lies in Madhya Pradesh and Chhattisgarh.
• The remaining basin lies in Andhra Pradesh.

Main Tributaries

• Penganga
• Indravati
• Pranhita
• Manjra

Krishna River System

The Krishna River is one of the major east-flowing rivers of Peninsular India.

It originates in Maharashtra and flows through Karnataka and Andhra Pradesh before meeting the Bay of Bengal.

Important Tributaries

Important tributaries include:

• Bhima
• Tungabhadra
• Ghataprabha
• Malaprabha
• Musi

Important Dam

The Krishna Raja Sagara Dam / Reservoir is associated with the Kaveri river system, not Krishna.

This distinction is useful for exams.

Kaveri River System

The Kaveri rises in the Brahmagiri Hills.

It flows through southern India and drains into the Bay of Bengal.

Importance

The Kaveri is important for irrigation, agriculture and deltaic farming in southern India.

It forms a fertile delta before entering the Bay of Bengal.

Narmada River System

The Narmada rises from Amarkantak.

It flows westward through a rift valley and drains into the Arabian Sea.

Unlike most Peninsular rivers, it does not form a large delta.

It forms an estuary.

Important Feature

The Narmada is known for its fault valley drainage.

Tapi River System

The Tapi also flows westward through a rift valley.

Like the Narmada, it drains into the Arabian Sea and forms an estuary.

It lacks large deltaic deposits because it flows through a trough fault.

Other Important Rivers And Drainage Points

Luni River

The Luni is an important river of Rajasthan.

It has freshwater in its upper course, but saline water in the lower part.

This is due to the arid conditions and inland drainage character of western Rajasthan.

Damodar River

The Damodar emerges from the Chotanagpur Plateau and is a tributary of the Hooghly.

It is also known for its rift valley-related drainage character.

Betwa River

The Betwa joins the Yamuna.

It is one of the important rivers of the northern Peninsular region joining the Ganga system.

Himalayan Drainage Vs Peninsular Drainage

Basis	Himalayan Drainage	Peninsular Drainage
Age	Younger	Older
Nature	Perennial	Mostly seasonal
Source of water	Snowmelt and rainfall	Mainly rainfall
Course	Long and highly erosive in mountains	Fixed and mature
Landforms	Gorges, V-shaped valleys, flood plains	Broad shallow valleys
Flow pattern	More dynamic	More stable
Main systems	Indus, Ganga, Brahmaputra	Mahanadi, Godavari, Krishna, Kaveri, Narmada, Tapi
Depositional features	Large flood plains and deltas	Smaller deltas; Narmada and Tapi form estuaries

Importance Of Drainage System Of India

India’s drainage system is important for physical geography, agriculture, settlements, transport and economy.

Major Importance

• Rivers provide water for irrigation.
• River plains support agriculture.
• River valleys support dense settlements.
• Rivers help in inland navigation in some regions.
• Rivers support hydropower generation.
• River systems shape landforms such as plains, deltas, gorges and valleys.
• River basins are important for planning water resources.
• Drainage systems influence soil formation and flood patterns.

Drainage System Of India At A Glance

Topic	Key Fact
Drainage	Flow of water through channels
Drainage system	Network of channels
Catchment area	Area from which a river collects water
Drainage basin	Area drained by river and tributaries
Watershed	Boundary separating drainage basins
Main genetic types	Sequent and insequent
Sequent types	Consequent, subsequent, obsequent, resequent
Insequent types	Superimposed and antecedent
Main drainage patterns	Dendritic, parallel, trellis, rectangular, radial, centripetal, pinnate, annular
Major river basin size	More than 20,000 square Km
Medium basin size	2,000 to 20,000 square Km
Minor basin size	Less than 2,000 square Km
Main Indian drainage systems	Himalayan and Peninsular
Himalayan rivers	Indus, Ganga, Brahmaputra
Peninsular rivers	Mahanadi, Godavari, Krishna, Kaveri, Narmada, Tapi
Largest Peninsular river system	Godavari
Godavari nickname	Dakshin Ganga
Mahanadi length	851 Km
Godavari length	1,465 Km
Brahmaputra name in Tibet	Tsangpo
Brahmaputra turn	Near Namcha Barwa
Ganga formation	Bhagirathi and Alaknanda at Devprayag
Narmada source	Amarkantak
Kaveri source	Brahmagiri Hills

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