Drainage

● River system: A river along with its tributaries.

● Drainage: River system of an area.

● Drainage basin: Area drained by a single river system.

● Water divide: An upland which divides two drainage basins.

● Perennial: Has water throughout the year.

● Meander: A curve of a river.

● Ox-bow lake: A small water body cut-off by meander from the

river.

● Gorge: A narrow valley between hills or mountains, with steep

rocky walls and a stream running through it.

● Headwaters: The source of a river.

● Distributary: A branch of a river which does not return after

leaving it.

● Braided Channel: A river channel with a network of branches that

merge and separate to form a braided pattern.
● Riverine Island: A landmass surrounded by water of a river.

● Mouth of a river: The point where the river enters a larger body of
water.

● Estuary: A body of water where a river meets an ocean, and is

home to unique plants and animal communities.

● Rift Valley: A lowland area that forms when tectonic plates move.

● Faulting: A process that occurs when the Earth’s crust breaks and
slides past itself.

● Spring: Occurs when water pressure causes a natural flow of

groundwater onto Earth’s surface.

● Coastal Spits: Narrow, elongated landforms that extend out into a

body of water, such as an ocean, sea, or lake, from a coastline.
They are typically formed through the accumulation of sediment,
deposited by waves, tides, or currents.

● Coastal Bars: Elongated ridges of sediment that form parallel to a

coastline, often detached from the mainland.

● Lagoons: Shallow bodies of water separated from the open sea by

a barrier, such as a coral reef, island, or coastal ridge.
Drainage systems in India
● The drainage systems are mainly controlled by the broad relief
features of the subcontinent.

● Accordingly, the Indian rivers are divided among to major groups:-

● Himalayan rivers
○ Most of the rivers are perennial. These rivers receive water
from rain as well as melted snow from the lofty mountains.

○ 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 have well developed deltas.

○ Major himalayan rivers: Indus, Ganga, Brahmaputra.

■ The Indus river system

● The Indus river rises in Tibet, near lake
Mansarowar.

● It enters India from the Eastern side of Ladakh.

● It forms a beautiful gorge in this part.

● Several tributaries – the Zaskar, the Nubra, the

Shyok and the Hunza – join it in the Kashmir
region.

● The Indus river flows through Balistan and Gilgit

and emerges from the mountains at Attock.

● Satluj, Chenab, Jhelum, Ravi and Beas join

together to enter the Indus near Mithankot in
Pakistan.

● The Indus then flows into the Arabian Sea, east of

Karachi.

● With a total length of 2900 km, Indus stands as

one of the longest rivers of the world.
 ● A little over 1/3rd of the Indus basin is located in
Ladakh, Jammu and Kashmir, Himachal Pradesh
and Punjab. The rest is in pakistan.

■ The Ganga river system

● The headwaters of Ganga, called the Bhagirathi, is
fed by the Gangotri Glacier and joined by the
Alaknanda at Devaprayag in Uttarakhand.
● At Haridwar, the Ganga merges from the
mountains onto the plains.
● Yamuna, Ghaghara, Gandak and Kosi join Ganga.
● Yamuna rises from the Yamunotri Glacier in the
Himalayas, meets Ganga at Allahabad.
● Ghaghara, Gandak and Kosi rise in the Nepal
Himalayas. They are the rivers which flood the
Northern Plain every year, but they also enrich
the soil for agricultural use.
● Chambal, Betwa and Son are the main tributaries
which come from peninsular uplands. They rise
from semi-arid areas, have shorter courses and
do not carry much water in them.Chambal and
Betwa meet to form Yamuna at Etawah, Uttar
Pradesh. Son meets Ganga in Patna, Bihar.
● Ganga flows eastwards till Farakka in West
Bengal. This is the northernmost point of the
Ganga Delta. The river bifurcates here.
● The river then is joined by Brahmaputra in
Bangladesh, Ganga and Brahmaputra combined
together is known as Meghna. The delta formed
by these rivers is known as the Sunderban Delta.
● The final length of Ganga is over 2500 km.
● Ambala is located on the water divide of Indus
and Ganga river systems. The plains from Ambala
to the Sunderban stretch over nearly 1800 km,
but the fall in its slope is hardly 300 m. There is a
fall of slope of 1 m for every 6km. Therefore, the
river develops large meanders.
■ The Brahmaputra river system
● Rises in Tibet, east of Mansarowar lake, very
close to the sources of Indus and Satluj.
● Slightly longer than Indus. Most of its course lies
outside India.
● It flows eastwards, parallel to the Himalayas.
● On reaching Namcha Barwa (a mountain of length
7757 m), it takes a ‘U’ turn and enters India in
Arunachal Pradesh through a gorge.
● Here (Arunachal Pradesh) it is called Dihang and
is joined by Dibang, Lohit and many other
tributaries to form Brahmaputra in Assam.
● In Tibet, the river carries a smaller volume of
water and less silt as it is a cold and dry area. In
India, it passes through a region of high rainfall
and carries a large volume of water and
considerable amount of silt.
● Brahmaputra has a braided channel in its entire
length in Assam and forms many riverine islands.
 ● Majuli is the world’s largest riverine island and is
formed by Brahmaputra in Assam.
● It floods many areas of Assam and Bangladesh
during the rainy season every year.

● Peninsular rivers
○ Many peninsular rivers are seasonal, as their flow depends
on rainfall.

○ These rivers have shorter and shallower courses compared to

their himalayan counterparts.

○ The main water divide is formed by the Western Ghats.

○ The drainage basins of the peninsular rivers are

comparatively smaller in size.

■ East Flowing rivers

○ Mahanadi, Godavari, Krishna and Kaveri drain into the Bay of
Bengal.
○ Make deltas at their mouths.

○ Godavari Basin
■ Largest peninsular river.
■ It’s drainage basin is also the largest among the
peninsular rivers. The basin covers parts of
Maharashtra, Madhya Pradesh, Odisha and Andhra
Pradesh.
■ About 50% of its basin lies in Maharashtra.
■ Rises from the slopes of the Western Ghats, Nasik,
Maharashtra.
■ About 1500 km long.
■ Drains into the Bay of Bengal.
 ■ Purna, Wardha, Pranhita, Manjra, Wainganga and
Penganga are the tributaries which join Godavari.
■ Due to its length, Godavari is also known as Dakshin
Ganga.

○ Mahanadi Basin
■ Rises in the Highlands of Chhattisgarh.
■ Flows through Odisha to reach the Bay of Bengal.
■ The river is about 860 km long.
■ It’s basin covers parts of Maharashtra, Chhattisgarh,
Jharkhand and Odisha.

○ Krishna Basin
■ Rising from a spring near Mahabaleshwar.
■ The river is about 1400 km long.
■ Tungabhadra, Koyana, Ghatprabha, Musi and Bhima are
some of its tributaries.
■ It’s basin covers parts of Maharashtra, Karnataka and
Andhra Pradesh.
○ Kaveri Basin
■ Rises in the Brahmagiri Range of the Western Ghats.
■ Reaches Bay of Bengal in south of Cuddalore in Tamil
Nadu.
■ The length of the river is about 760 km.
■ Amravati, Bhavani, Hemavati and Kabini are its main
tributaries.
■ It’s basin drains parts of Karnataka, Kerala and Tamil
Nadu

■ West flowing rivers

○ Narmada and Tapi are the only rivers that flow westwards
and make estuaries.

○ Narmada Basin
■ Rises in Amarkantak Hills in Madhya Pradesh.
■ Flows west in a rift valley formed due to faulting.
 ■ The ‘Marble Rocks’ near Jabalpur, the Narmada flows
through a deep gorge, and the ‘Dhuandhar Falls’, where
the river plunges over steep rocks.
■ The tributaries of Narmada are very short and most of
these join the mainstream at right angles.
■ The Narmada Basin covers parts of Madhya Pradesh
and Gujarat.

○ Tapi Basin
■ Rises in the Satpura Ranges, Betul, Madhya Pradesh.
■ Also flows in a rift valley parallel to Narmada, but much
shorter in length.
■ Its basin covers parts of Madhya Pradesh, Gujarat and
Maharashtra.
■ The coastal plains between the Western Ghats and the
Arabian Sea are very narrow, hence, the coastal rivers
are short.
Lakes
● Spits and bars form lagoons in the coastal areas, e.g. the Chilika
lake, the Pulicat lake and the Kolleru lake.
● Lakes in the region of inland drainage are sometimes seasonal, e.g.
the Sambhar lake in Rajasthan. Its water is used for producing
salt.
● Most of the freshwater lakes are in the Himalayan region, they are
formed when glaciers dug out a basin, which was then later filled
with snowmelt.
● The Wular lake in Jammu and Kashmir is the result of tectonic
activity, and is the biggest freshwater lake of India.
● Dal lake, Bhimtal, Nainital, Loktak and Barapani are some other
examples of freshwater lakes.
● Apart from natural lakes, the damming of the rivers for the
generation of hydel power has also led to the formation of lakes,
such as Guru Gobind Sagar.
● During the rainy season, a lake prevents flooding and during the
dry season, it helps to maintain an even flow of water.
● Lakes can also be used for developing Hydel Power.
● They moderate the climate of the surroundings.
 ● Maintain the aquatic ecosystem, enhance natural beauty, help
develop tourism and provide recreation.

River pollution
● The growing demand of water from rivers naturally affect the
quality of water, as a result more and more water is being drained
out of the rivers reducing their volume.
● A heavy load of untreated sewage and industrial effluents are
emptied into the rivers. This affects not only the quality of water
but also the self-cleansing capacity of water.

NATIONAL RIVER CONSERVATION PLAN

(NRCP)

● The river cleaning programme in the country was initiated with

the launch of the Ganga Action Plan (GAP) in 1985.
● The GAP was expanded to cover other rivers under the NRCP in
1995.
● The objective of NRCP is to improve water quality of rivers
through the implementation of pollution abatement work.

DO YOU KNOWs

1. World’s largest drainage basin is of the Amazon river.

2. According to the regulations of the Indus Water Treaty
(1960):
a. India can use only 20% of the total water carried by
the Indus river system.
b. This water is used for irrigation in Punjab, Haryana and
the southern and western parts of Rajasthan.
3. The Namami Gange Programme is an Integrated
Conservation Mission approved as a ‘flagship programme’
by the Union Government in June 2014 to accomplish twin
objectives of abatement of pollution, conservation
and rejuvenation of Ganga.
4. Sundarban Delta:
a. Derived its name from the Sundari tree, which grows
well in marshland.
b. It is the world’s largest and fastest growing delta.
c. Also the home of the Royal Bengal Tiger.
5. The Narmada River Conservation Mission has been
undertaken by the government of Madhya Pradesh by a
scheme named Namami Devi Narmade.
6. The river Kaveri makes the second biggest waterfall in India,
known as the Shivasamudram Falls. The hydroelectric
power generated by the falls is supplied to Mysore,
Bengaluru and the Kolar Gold Field.
7. Water and Freshwater:
a. Out of the total, 71% of the world’s surface is covered
with water, but 97% of that is salt water.
b. Of the 3% that is available as freshwater, three
quarters of it is trapped as ice.