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 Page 1


DRAINAGE
T
he term drainage describes the river
system of an area. Look at the physical
map. You will notice that small streams
flowing from different directions come together
to form the main river, which ultimately drains
into a large water body such as a lake or a sea
or an ocean. The area drained by a single river
system is called a drainage basin. A closer
observation on a map will indicate that any
elevated area, such as a mountain or an upland,
separates two drainage basins. Such an upland
is known as a water divide (Figure 3.1).
Figure 3.2 : A Gorge
DRAINAGE SYSTEMS IN INDIA
The drainage systems of India are mainly
controlled by the broad relief features of the
subcontinent. Accordingly, the Indian rivers
are divided into two major groups:
• the Himalayan rivers; and
• the Peninsular rivers.
Apart from originating from the two major
physiographic regions of India, the Himalayan
and the Peninsular rivers are different from
each other in many ways. Most of the
Himalayan rivers are perennial.  It means
that they have water throughout the year.
These rivers receive  water from rain as well
as from melted snow from the lofty
mountains. The two major Himalayan rivers,
the Indus and the Brahmaputra originate
from the north of the mountain ranges. They
have cut through the mountains making
gorges. The Himalayan rivers have long
courses from their source to the sea.
3
Water Divide
Sream A
Sream B
Figure 3.1 : Water Divide
The world’s largest drainage
basin is of the Amazon river
• Which river has the largest basin in India?
Stream  A
Stream B
2024-25
Page 2


DRAINAGE
T
he term drainage describes the river
system of an area. Look at the physical
map. You will notice that small streams
flowing from different directions come together
to form the main river, which ultimately drains
into a large water body such as a lake or a sea
or an ocean. The area drained by a single river
system is called a drainage basin. A closer
observation on a map will indicate that any
elevated area, such as a mountain or an upland,
separates two drainage basins. Such an upland
is known as a water divide (Figure 3.1).
Figure 3.2 : A Gorge
DRAINAGE SYSTEMS IN INDIA
The drainage systems of India are mainly
controlled by the broad relief features of the
subcontinent. Accordingly, the Indian rivers
are divided into two major groups:
• the Himalayan rivers; and
• the Peninsular rivers.
Apart from originating from the two major
physiographic regions of India, the Himalayan
and the Peninsular rivers are different from
each other in many ways. Most of the
Himalayan rivers are perennial.  It means
that they have water throughout the year.
These rivers receive  water from rain as well
as from melted snow from the lofty
mountains. The two major Himalayan rivers,
the Indus and the Brahmaputra originate
from the north of the mountain ranges. They
have cut through the mountains making
gorges. The Himalayan rivers have long
courses from their source to the sea.
3
Water Divide
Sream A
Sream B
Figure 3.1 : Water Divide
The world’s largest drainage
basin is of the Amazon river
• Which river has the largest basin in India?
Stream  A
Stream B
2024-25
18 CONTEMPORARY INDIA-I
They perform intensive erosional activity in
their upper courses and carry huge loads of
silt and sand. In the middle and the lower
courses, these rivers form meanders, oxbow
lakes, and many other depositional features
in their floodplains. They also have well-
developed deltas (Figure 3.3).
A large number of the Peninsular rivers are
seasonal, as their flow is dependent on rainfall.
During the dry season, even the large rivers
have reduced flow of water in their channels.
The Peninsular rivers have shorter and
shallower courses as compared to their
Himalayan counterparts. However, some of
them originate in the central highlands and flow
towards the west. Can you identify two such
large rivers? Most of the rivers of peninsular
India originate in the Western Ghats and flow
towards the Bay of Bengal.
Source of River
Upper Course
Middle Course
Ox-Bow Lake
Lower
Course
Meander
Delta
Figure 3.3 : Some Features Made by Rivers
The Himalayan Rivers
The major Himalayan rivers are the Indus, the
Ganga and the Brahmaputra. These rivers are
long, and are joined by many large and
important tributaries. A river alongwith its
tributaries may be called a river system.
The Indus River System
The river Indus rises in Tibet, near Lake
Mansarowar . Flowing west, it enters India in the
Ladakh. It forms a picturesque gorge in this
part. Several tributaries, the Zaskar, the Nubra,
the Shyok and the Hunza, join it in the Kashmir
region. The Indus flows through Baltistan and
Gilgit and emerges from the mountains at Attock.
The Satluj, the Beas, the Ravi, the Chenab and
the Jhelum join together to enter the Indus near
Mithankot in Pakistan. Beyond this, the Indus
flows southwards eventually reaching the
Arabian Sea, east of Karachi.   The Indus plain
has a very gentle slope. With a total length of
2900 km, the Indus is one of the longest rivers
of the world. A little over a third of the Indus
basin is located in India Ladakh, Jammu and
Kashmir, Himachal Pradesh and Punjab and the
rest is in Pakistan.
• According to the regulations
of the Indus Water Treaty (1960), India can
use only 20 per cent of the total water carried by
the Indus river system. This water is used for
irrigation in Punjab, Haryana and the southern
and the western parts of Rajasthan.
The Ganga River System
The headwaters of the Ganga, called the
‘Bhagirathi’ is fed by the Gangotri Glacier and
joined by the Alaknanda at Devaprayag in
Uttarakhand. At Haridwar, the Ganga emerges
from the mountains on to the plains.
2024-25
Page 3


DRAINAGE
T
he term drainage describes the river
system of an area. Look at the physical
map. You will notice that small streams
flowing from different directions come together
to form the main river, which ultimately drains
into a large water body such as a lake or a sea
or an ocean. The area drained by a single river
system is called a drainage basin. A closer
observation on a map will indicate that any
elevated area, such as a mountain or an upland,
separates two drainage basins. Such an upland
is known as a water divide (Figure 3.1).
Figure 3.2 : A Gorge
DRAINAGE SYSTEMS IN INDIA
The drainage systems of India are mainly
controlled by the broad relief features of the
subcontinent. Accordingly, the Indian rivers
are divided into two major groups:
• the Himalayan rivers; and
• the Peninsular rivers.
Apart from originating from the two major
physiographic regions of India, the Himalayan
and the Peninsular rivers are different from
each other in many ways. Most of the
Himalayan rivers are perennial.  It means
that they have water throughout the year.
These rivers receive  water from rain as well
as from melted snow from the lofty
mountains. The two major Himalayan rivers,
the Indus and the Brahmaputra originate
from the north of the mountain ranges. They
have cut through the mountains making
gorges. The Himalayan rivers have long
courses from their source to the sea.
3
Water Divide
Sream A
Sream B
Figure 3.1 : Water Divide
The world’s largest drainage
basin is of the Amazon river
• Which river has the largest basin in India?
Stream  A
Stream B
2024-25
18 CONTEMPORARY INDIA-I
They perform intensive erosional activity in
their upper courses and carry huge loads of
silt and sand. In the middle and the lower
courses, these rivers form meanders, oxbow
lakes, and many other depositional features
in their floodplains. They also have well-
developed deltas (Figure 3.3).
A large number of the Peninsular rivers are
seasonal, as their flow is dependent on rainfall.
During the dry season, even the large rivers
have reduced flow of water in their channels.
The Peninsular rivers have shorter and
shallower courses as compared to their
Himalayan counterparts. However, some of
them originate in the central highlands and flow
towards the west. Can you identify two such
large rivers? Most of the rivers of peninsular
India originate in the Western Ghats and flow
towards the Bay of Bengal.
Source of River
Upper Course
Middle Course
Ox-Bow Lake
Lower
Course
Meander
Delta
Figure 3.3 : Some Features Made by Rivers
The Himalayan Rivers
The major Himalayan rivers are the Indus, the
Ganga and the Brahmaputra. These rivers are
long, and are joined by many large and
important tributaries. A river alongwith its
tributaries may be called a river system.
The Indus River System
The river Indus rises in Tibet, near Lake
Mansarowar . Flowing west, it enters India in the
Ladakh. It forms a picturesque gorge in this
part. Several tributaries, the Zaskar, the Nubra,
the Shyok and the Hunza, join it in the Kashmir
region. The Indus flows through Baltistan and
Gilgit and emerges from the mountains at Attock.
The Satluj, the Beas, the Ravi, the Chenab and
the Jhelum join together to enter the Indus near
Mithankot in Pakistan. Beyond this, the Indus
flows southwards eventually reaching the
Arabian Sea, east of Karachi.   The Indus plain
has a very gentle slope. With a total length of
2900 km, the Indus is one of the longest rivers
of the world. A little over a third of the Indus
basin is located in India Ladakh, Jammu and
Kashmir, Himachal Pradesh and Punjab and the
rest is in Pakistan.
• According to the regulations
of the Indus Water Treaty (1960), India can
use only 20 per cent of the total water carried by
the Indus river system. This water is used for
irrigation in Punjab, Haryana and the southern
and the western parts of Rajasthan.
The Ganga River System
The headwaters of the Ganga, called the
‘Bhagirathi’ is fed by the Gangotri Glacier and
joined by the Alaknanda at Devaprayag in
Uttarakhand. At Haridwar, the Ganga emerges
from the mountains on to the plains.
2024-25
DRAINAGE 19
Figure 3.4 : Major Rivers and Lakes
2024-25
Page 4


DRAINAGE
T
he term drainage describes the river
system of an area. Look at the physical
map. You will notice that small streams
flowing from different directions come together
to form the main river, which ultimately drains
into a large water body such as a lake or a sea
or an ocean. The area drained by a single river
system is called a drainage basin. A closer
observation on a map will indicate that any
elevated area, such as a mountain or an upland,
separates two drainage basins. Such an upland
is known as a water divide (Figure 3.1).
Figure 3.2 : A Gorge
DRAINAGE SYSTEMS IN INDIA
The drainage systems of India are mainly
controlled by the broad relief features of the
subcontinent. Accordingly, the Indian rivers
are divided into two major groups:
• the Himalayan rivers; and
• the Peninsular rivers.
Apart from originating from the two major
physiographic regions of India, the Himalayan
and the Peninsular rivers are different from
each other in many ways. Most of the
Himalayan rivers are perennial.  It means
that they have water throughout the year.
These rivers receive  water from rain as well
as from melted snow from the lofty
mountains. The two major Himalayan rivers,
the Indus and the Brahmaputra originate
from the north of the mountain ranges. They
have cut through the mountains making
gorges. The Himalayan rivers have long
courses from their source to the sea.
3
Water Divide
Sream A
Sream B
Figure 3.1 : Water Divide
The world’s largest drainage
basin is of the Amazon river
• Which river has the largest basin in India?
Stream  A
Stream B
2024-25
18 CONTEMPORARY INDIA-I
They perform intensive erosional activity in
their upper courses and carry huge loads of
silt and sand. In the middle and the lower
courses, these rivers form meanders, oxbow
lakes, and many other depositional features
in their floodplains. They also have well-
developed deltas (Figure 3.3).
A large number of the Peninsular rivers are
seasonal, as their flow is dependent on rainfall.
During the dry season, even the large rivers
have reduced flow of water in their channels.
The Peninsular rivers have shorter and
shallower courses as compared to their
Himalayan counterparts. However, some of
them originate in the central highlands and flow
towards the west. Can you identify two such
large rivers? Most of the rivers of peninsular
India originate in the Western Ghats and flow
towards the Bay of Bengal.
Source of River
Upper Course
Middle Course
Ox-Bow Lake
Lower
Course
Meander
Delta
Figure 3.3 : Some Features Made by Rivers
The Himalayan Rivers
The major Himalayan rivers are the Indus, the
Ganga and the Brahmaputra. These rivers are
long, and are joined by many large and
important tributaries. A river alongwith its
tributaries may be called a river system.
The Indus River System
The river Indus rises in Tibet, near Lake
Mansarowar . Flowing west, it enters India in the
Ladakh. It forms a picturesque gorge in this
part. Several tributaries, the Zaskar, the Nubra,
the Shyok and the Hunza, join it in the Kashmir
region. The Indus flows through Baltistan and
Gilgit and emerges from the mountains at Attock.
The Satluj, the Beas, the Ravi, the Chenab and
the Jhelum join together to enter the Indus near
Mithankot in Pakistan. Beyond this, the Indus
flows southwards eventually reaching the
Arabian Sea, east of Karachi.   The Indus plain
has a very gentle slope. With a total length of
2900 km, the Indus is one of the longest rivers
of the world. A little over a third of the Indus
basin is located in India Ladakh, Jammu and
Kashmir, Himachal Pradesh and Punjab and the
rest is in Pakistan.
• According to the regulations
of the Indus Water Treaty (1960), India can
use only 20 per cent of the total water carried by
the Indus river system. This water is used for
irrigation in Punjab, Haryana and the southern
and the western parts of Rajasthan.
The Ganga River System
The headwaters of the Ganga, called the
‘Bhagirathi’ is fed by the Gangotri Glacier and
joined by the Alaknanda at Devaprayag in
Uttarakhand. At Haridwar, the Ganga emerges
from the mountains on to the plains.
2024-25
DRAINAGE 19
Figure 3.4 : Major Rivers and Lakes
2024-25
20 CONTEMPORARY INDIA-I
The Ganga is joined by many tributaries
from the Himalayas, a few of them being major
rivers, such as the Yamuna, the Ghaghara, the
Gandak and the Kosi. The river Yamuna rises
from the Yamunotri Glacier in the Himalayas.
It flows parallel to the Ganga and as a right
bank tributary meets the Ganga at Allahabad.
The Ghaghara, the Gandak and the Kosi rise
in the Nepal Himalaya. They are the rivers,
which flood parts of the northern plains every
year, causing widespread damage to life and
property, whereas, they enrich the soil for
agricultural use.
The main tributaries, which come from the
peninsular uplands, are the Chambal, the
Betwa and the Son. These rise from semi-arid
areas, have shorter courses and do not carry
much water in them. Find out where and how
they ultimately join the Ganga.
Figure 3.5 : Confluence of Bhagirathi and Alaknanda at
Devaprayag
                         • The Namami Gange Programme
is an Integrated Conservation Mission approved as
a ‘flagship programme’ by the Union Government
in June 2014 to accomplish the twin objectives of
effective abatement of pollution, conservation and
rejuvenation of the national river, Ganga. You may
explore about this project at http://nmcg.nic.in/
NamamiGanga.sspx#
Enlarged with the waters from its right and
left bank tributaries, the Ganga flows
eastwards till Farakka in West Bengal. This is
the northernmost point of the Ganga delta. The
river bifurcates here; the Bhagirathi-Hooghly
(a distributary) flows southwards through the
deltaic plains to the Bay of Bengal. The
mainstream, flows southwards into
Bangladesh and is joined by the Brahmaputra.
Further downstream, it is known as the
Meghna. This mighty river, with waters from
the Ganga and the Brahmaputra, flows into
the Bay of Bengal. The delta formed by these
rivers is known as the Sundarban Delta.
• The Sundarban Delta derived
its name from the Sundari tree, which grows well
in marshland.
•  It is the world’s largest and fastest growing delta.
It is also the home of Royal Bengal tiger.
The  length of the Ganga is over 2500 km.
Look at Figure 3.4; can you identify the type of
drainage pattern formed by the Ganga river
system? Ambala is located on the water divide
between the Indus and the Ganga river systems.
The plains from Ambala to the Sunderban
stretch over nearly 1800 km, but the fall in its
slope is hardly 300 metres. In other words, there
is a fall of just one metre for every 6 km.
Therefore, the river develops large meanders.
The Brahmaputra River System
The Brahmaputra rises in Tibet east of
Mansarowar lake very close to the sources of
the Indus and the Satluj. It is slightly longer
than the Indus, and most of its course lies
outside India. It flows eastwards parallel to
the Himalayas. On reaching the Namcha
Barwa (7757 m), it takes a ‘U’ turn and enters
India in Arunachal Pradesh through a gorge.
Here, it is called the Dihang and it is joined by
the Dibang, the Lohit, and many other
tributaries to form the Brahmaputra in Assam.
•  Brahmaputra is known as
the Tsang Po in Tibet and Jamuna in Bangladesh.
2024-25
Page 5


DRAINAGE
T
he term drainage describes the river
system of an area. Look at the physical
map. You will notice that small streams
flowing from different directions come together
to form the main river, which ultimately drains
into a large water body such as a lake or a sea
or an ocean. The area drained by a single river
system is called a drainage basin. A closer
observation on a map will indicate that any
elevated area, such as a mountain or an upland,
separates two drainage basins. Such an upland
is known as a water divide (Figure 3.1).
Figure 3.2 : A Gorge
DRAINAGE SYSTEMS IN INDIA
The drainage systems of India are mainly
controlled by the broad relief features of the
subcontinent. Accordingly, the Indian rivers
are divided into two major groups:
• the Himalayan rivers; and
• the Peninsular rivers.
Apart from originating from the two major
physiographic regions of India, the Himalayan
and the Peninsular rivers are different from
each other in many ways. Most of the
Himalayan rivers are perennial.  It means
that they have water throughout the year.
These rivers receive  water from rain as well
as from melted snow from the lofty
mountains. The two major Himalayan rivers,
the Indus and the Brahmaputra originate
from the north of the mountain ranges. They
have cut through the mountains making
gorges. The Himalayan rivers have long
courses from their source to the sea.
3
Water Divide
Sream A
Sream B
Figure 3.1 : Water Divide
The world’s largest drainage
basin is of the Amazon river
• Which river has the largest basin in India?
Stream  A
Stream B
2024-25
18 CONTEMPORARY INDIA-I
They perform intensive erosional activity in
their upper courses and carry huge loads of
silt and sand. In the middle and the lower
courses, these rivers form meanders, oxbow
lakes, and many other depositional features
in their floodplains. They also have well-
developed deltas (Figure 3.3).
A large number of the Peninsular rivers are
seasonal, as their flow is dependent on rainfall.
During the dry season, even the large rivers
have reduced flow of water in their channels.
The Peninsular rivers have shorter and
shallower courses as compared to their
Himalayan counterparts. However, some of
them originate in the central highlands and flow
towards the west. Can you identify two such
large rivers? Most of the rivers of peninsular
India originate in the Western Ghats and flow
towards the Bay of Bengal.
Source of River
Upper Course
Middle Course
Ox-Bow Lake
Lower
Course
Meander
Delta
Figure 3.3 : Some Features Made by Rivers
The Himalayan Rivers
The major Himalayan rivers are the Indus, the
Ganga and the Brahmaputra. These rivers are
long, and are joined by many large and
important tributaries. A river alongwith its
tributaries may be called a river system.
The Indus River System
The river Indus rises in Tibet, near Lake
Mansarowar . Flowing west, it enters India in the
Ladakh. It forms a picturesque gorge in this
part. Several tributaries, the Zaskar, the Nubra,
the Shyok and the Hunza, join it in the Kashmir
region. The Indus flows through Baltistan and
Gilgit and emerges from the mountains at Attock.
The Satluj, the Beas, the Ravi, the Chenab and
the Jhelum join together to enter the Indus near
Mithankot in Pakistan. Beyond this, the Indus
flows southwards eventually reaching the
Arabian Sea, east of Karachi.   The Indus plain
has a very gentle slope. With a total length of
2900 km, the Indus is one of the longest rivers
of the world. A little over a third of the Indus
basin is located in India Ladakh, Jammu and
Kashmir, Himachal Pradesh and Punjab and the
rest is in Pakistan.
• According to the regulations
of the Indus Water Treaty (1960), India can
use only 20 per cent of the total water carried by
the Indus river system. This water is used for
irrigation in Punjab, Haryana and the southern
and the western parts of Rajasthan.
The Ganga River System
The headwaters of the Ganga, called the
‘Bhagirathi’ is fed by the Gangotri Glacier and
joined by the Alaknanda at Devaprayag in
Uttarakhand. At Haridwar, the Ganga emerges
from the mountains on to the plains.
2024-25
DRAINAGE 19
Figure 3.4 : Major Rivers and Lakes
2024-25
20 CONTEMPORARY INDIA-I
The Ganga is joined by many tributaries
from the Himalayas, a few of them being major
rivers, such as the Yamuna, the Ghaghara, the
Gandak and the Kosi. The river Yamuna rises
from the Yamunotri Glacier in the Himalayas.
It flows parallel to the Ganga and as a right
bank tributary meets the Ganga at Allahabad.
The Ghaghara, the Gandak and the Kosi rise
in the Nepal Himalaya. They are the rivers,
which flood parts of the northern plains every
year, causing widespread damage to life and
property, whereas, they enrich the soil for
agricultural use.
The main tributaries, which come from the
peninsular uplands, are the Chambal, the
Betwa and the Son. These rise from semi-arid
areas, have shorter courses and do not carry
much water in them. Find out where and how
they ultimately join the Ganga.
Figure 3.5 : Confluence of Bhagirathi and Alaknanda at
Devaprayag
                         • The Namami Gange Programme
is an Integrated Conservation Mission approved as
a ‘flagship programme’ by the Union Government
in June 2014 to accomplish the twin objectives of
effective abatement of pollution, conservation and
rejuvenation of the national river, Ganga. You may
explore about this project at http://nmcg.nic.in/
NamamiGanga.sspx#
Enlarged with the waters from its right and
left bank tributaries, the Ganga flows
eastwards till Farakka in West Bengal. This is
the northernmost point of the Ganga delta. The
river bifurcates here; the Bhagirathi-Hooghly
(a distributary) flows southwards through the
deltaic plains to the Bay of Bengal. The
mainstream, flows southwards into
Bangladesh and is joined by the Brahmaputra.
Further downstream, it is known as the
Meghna. This mighty river, with waters from
the Ganga and the Brahmaputra, flows into
the Bay of Bengal. The delta formed by these
rivers is known as the Sundarban Delta.
• The Sundarban Delta derived
its name from the Sundari tree, which grows well
in marshland.
•  It is the world’s largest and fastest growing delta.
It is also the home of Royal Bengal tiger.
The  length of the Ganga is over 2500 km.
Look at Figure 3.4; can you identify the type of
drainage pattern formed by the Ganga river
system? Ambala is located on the water divide
between the Indus and the Ganga river systems.
The plains from Ambala to the Sunderban
stretch over nearly 1800 km, but the fall in its
slope is hardly 300 metres. In other words, there
is a fall of just one metre for every 6 km.
Therefore, the river develops large meanders.
The Brahmaputra River System
The Brahmaputra rises in Tibet east of
Mansarowar lake very close to the sources of
the Indus and the Satluj. It is slightly longer
than the Indus, and most of its course lies
outside India. It flows eastwards parallel to
the Himalayas. On reaching the Namcha
Barwa (7757 m), it takes a ‘U’ turn and enters
India in Arunachal Pradesh through a gorge.
Here, it is called the Dihang and it is joined by
the Dibang, the Lohit, and many other
tributaries to form the Brahmaputra in Assam.
•  Brahmaputra is known as
the Tsang Po in Tibet and Jamuna in Bangladesh.
2024-25
DRAINAGE 21
In Tibet, the river carries a smaller volume of
water and less silt as it is a cold and a dry area.
In India, it passes through a region of high
rainfall. Here the river carries a large volume of
water and considerable amount of silt. The
Brahmaputra has a braided channel in its entire
length in Assam and forms many riverine islands.
Do you remember the name of the world’s largest
riverine island formed by the Brahmaputra?
Every year during the rainy season, the
river overflows its banks, causing widespread
devastation due to floods in Assam and
Bangladesh. Unlike other north Indian rivers,
the Brahmaputra is marked by huge deposits
of silt on its bed causing  the riverbed to rise.
The river also shifts its channel frequently.
The Peninsular Rivers
The main water divide in Peninsular India is
formed by the Western Ghats, which runs from
north to south close to the western coast.  Most
of the major rivers of the Peninsula, such as
the Mahanadi, the Godavari, the Krishna and
the Kaveri flow eastwards and drain into the
Bay of Bengal. These rivers make deltas at
their mouths. There are numerous small
streams flowing west of the Western Ghats.
The Narmada and the Tapi are the only long
rivers, which flow west and make esturies.  The
drainage basins of the peninsular rivers are
comparatively smaller in size.
The Narmada Basin
The Narmada rises in the Amarkantak hills
in Madhya Pradesh. It flows towards the west
in a rift valley formed due to faulting. On its
way to the sea, the Narmada creates many
picturesque locations. The ‘Marble rocks’,
near Jabalpur, where the Narmada flows
through a deep gorge, and the ‘Dhuadhar
falls, where the river plunges over steep rocks,
are some of the notable ones.
               • The Narmada river
conservation mission has been undertaken by the
government of Madhya Pradesh by a scheme named
Namami Devi Narmade. You may visit their website.
http://www.namamidevinarmade.mp.gov.in to
learn more about it.
All tributaries of the Narmada are very short
and most of these join the main stream at right
angles. The Narmada basin covers parts of
Madhya Pradesh and Gujarat.
The Tapi Basin
The Tapi rises in the Satpura ranges, in the
Betul district of Madhya Pradesh. It also flows
in a rift valley parallel to the Narmada but it is
much shorter in length. Its basin covers parts
of Madhya Pradesh, Gujarat and Maharashtra.
The coastal plains between Western Ghats
and the Arabian Sea are very narrow. Hence,
the coastal rivers are short. The main west
flowing rivers are Sabarmati, Mahi,
Bharathpuzha and Periyar. Find out the states
in which these rivers drain the water.
The Godavari Basin
The Godavari is the largest Peninsular river. It
rises from the slopes of the Western Ghats in
the Nasik district of Maharashtra. Its length is
about 1500 km.  It drains into the Bay of Bengal.
Its drainage basin is also the largest among the
peninsular rivers. The basin covers parts of
Maharashtra (about 50 per cent of the basin
area lies in Maharashtra), Madhya Pradesh,
Odisha and Andhra Pradesh. The Godavari is
joined by a number of tributaries, such as the
Purna, the Wardha, the Pranhita, the Manjra,
the W ainganga and the Penganga.  The last three
tributaries are very large. Because of its length
and the area it covers, it is also known as the
Dakshin Ganga.
The Mahanadi Basin
The Mahanadi rises in the highlands of
Chhattisgarh. It flows through Odisha to reach
2024-25
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FAQs on NCERT Textbook: Drainage - Geography (Prelims) by Valor Academy - UPSC

1. What is drainage?
Ans. Drainage is the process of removing excess water from the surface of the earth. It involves the collection, transportation, and disposal of water from places where it is not required, such as roads, buildings, and agricultural fields. Proper drainage systems are essential to prevent flooding, waterlogging, and soil erosion.
2. What are the types of drainage systems?
Ans. There are two types of drainage systems - surface drainage and subsurface drainage. Surface drainage includes natural and artificial features that collect and remove water from the surface. Natural features include rivers, lakes, and wetlands, while artificial features include canals, ditches, and gutters. Subsurface drainage involves the removal of water from the soil or rock layers beneath the surface. It includes systems such as drain tiles, French drains, and subsoil drains.
3. Why is proper drainage important for agriculture?
Ans. Proper drainage is essential for agriculture as it helps to maintain soil health and productivity. Excess water can lead to waterlogging, which reduces the availability of oxygen to the roots and can cause plant death. It also leads to the leaching of essential nutrients from the soil, reducing soil fertility. Drainage helps to maintain soil moisture levels, allowing for proper root development and nutrient uptake. It also prevents soil erosion, which can cause significant losses in agricultural productivity.
4. How does urbanization affect drainage systems?
Ans. Urbanization has a significant impact on drainage systems. As cities grow, there is an increase in impermeable surfaces such as roads, buildings, and pavements, which reduce the amount of water that can infiltrate the soil. This leads to increased runoff and flooding during heavy rainfall events. Urbanization also increases the amount of pollution in stormwater runoff, which can have negative impacts on aquatic ecosystems.
5. What are the environmental benefits of proper drainage systems?
Ans. Proper drainage systems provide numerous environmental benefits. They help to reduce the risk of flooding, which can cause significant damage to homes, businesses, and infrastructure. Drainage also helps to prevent soil erosion and maintain soil fertility, which is essential for healthy ecosystems. Proper drainage systems can also improve water quality by reducing the amount of pollutants that enter streams, rivers, and lakes.
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