DRAINAGE & RIVER SYSTEMS
1.
The term drainage describes the
river system of an area.
2.
The area drained by a single
river system is called a drainage basin.
Water
divide
Any
elevated area, such as a mountain or upland, separates two drainage basins.
Such an upland is known as a water divide
The world’s largest drainage basin
is of the Nile River in Egypt
DRAINAGE
SYSTEMS IN INDIA
1.
The drainage systems of India
are mainly controlled by the broad relief features of the subcontinent.
2.
The Indian rivers are divided
into two major groups:
The Himalayan Rivers
1.
Most of the Himalayan Rivers
are perennial.
2.
The two major Himalayan Rivers,
the Indus and the Brahmaputra
originate from the north of the mountain ranges.
3.
They have cut through the
mountains making gorges.
4.
The Himalayan Rivers have long
courses from their source to the sea.
5.
They perform intensive
erosional activity in their upper courses and carry huge loads of silt and
sand.
6.
In the middle and the lower
courses, these rivers form meanders, oxbow lakes, and many other depositional
features
The Peninsular Rivers
1.
A large number of the
Peninsular Rivers are seasonal
The
Himalayan Rivers
The major
Himalayan Rivers are the Indus, the Ganga and the Brahmaputra.
River system -
A river
along with its tributaries may be called a river system.
The
Indus River System
1.
The river Indus rises in Tibet,
near Lake Mansarowar.
2.
Flowing west, it enters India
in the Ladakh district of Jammu and Kashmir.
3.
It forms a picturesque gorge in
this part.
4.
Several tributaries, the
Zaskar, the Nubra, the Shyok and the Hunza, join it in the Kashmir region.
5.
The Indus flows through
Baltistan and Gilgit and emerges from the mountains at Attock.
6.
The Satluj, the Beas, the Ravi,
the Chenab and the Jhelum join together to enter the Indus near Mithankot in
Pakistan.
7.
Beyond this, the Indus flows
southwards eventually reaching the Arabian Sea, east of Karachi.
8.
The Indus plain has a very
gentle slope.
9.
With a total length of 2900 km
10.
A little over a third of the
Indus basin is located in India in the states of Jammu and Kashmir, Himachal
Pradesh and the 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
Indus river system. This water is used for irrigation in the Punjab, Haryana
and the southern and western parts of Rajasthan
The Ganga
River System
1.
The headwaters of the Ganga,
called the ‘Bhagirathi’ is fed by the Gangotri Glacier and joined by the
Alaknanda at Devaprayag in Uttaranchal.
2.
At Haridwar the Ganga emerges
from the mountains on to the plains.
3.
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.
4.
The river Yamuna rises from the
Yamunotri Glacier in the Himalayas.
5.
It flows parallel to the Ganga
and as a right bank tributary, meets the Ganga at Allahabad
6.
The Ghaghara, the Gandak and
the Kosi rise in the Nepal Himalaya.
7.
They are the rivers, which
flood parts of the northern plains every year, causing widespread damage to
life and property but enriching the soil for the extensive agricultural lands.
8.
The main tributaries, which
come from the peninsular uplands, are the Chambal, the Betwa and the Son.
9.
These rise from semi-arid
areas, have shorter courses and do not carry much water in them.
10.
The Ganga flows eastwards till
Farakka in West Bengal.
11.
This is the northernmost point
of the Ganga delta
12.
The river bifurcates here; the
Bhagirathi-Hooghly (a distributary) flows southwards through the deltaic plains
to the Bay of Bengal.
13.
The mainstream, flows southwards
into Bangladesh and is joined by the Brahmaputra.
14.
Further downstream, it is known
as the Meghna.
15.
The length of the Ganga is over
2500 km.
16.
Ambala is located on the water
divide between the Indus and the Ganga river systems.
17.
The plains from Ambala to the
Sunderban stretch over nearly 1800 km, but the fall in its slope is hardly 300
metres.
18.
In other words, there is a fall of just one
metre for every 6 km. Therefore, the river develops large meanders.
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 Sunderban 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
Brahmaputra River System
1.
The Brahmaputra rises in Tibet
east of Mansarowar Lake very close to the sources of the Indus and the Satluj.
2.
It is slightly longer than the
Indus, and most of its course lies outside India.
3.
It flows eastwards parallel to
the Himalayas. On reaching the Namcha Barwa (7757 m), it takes a ‘U’ turn
4.
Enters India in Arunachal Pradesh through a gorge.
5.
Here, it is called the Dihang
and it is joined by the Dibang, the Lohit, the Kenula and
6.
Many other tributaries to form
the Brahmaputra in Assam
7.
Brahmaputra is known as the
Tsang Po in Tibet and Jamuna in Bangladesh.
8.
In Tibet the river carries a
smaller volume of water and less silt as it is a cold and a dry area
9.
In India it passes through a
region of high rainfall.
10.
Here the river carries a large
volume of water and considerable amount of silt.
11.
The Brahmaputra has a braided
channel in its entire length in Assam and forms many riverine islands
12.
Unlike other north Indian
rivers the Brahmaputra is marked by huge deposits of silt on its bed causing
the river bed to rise. The river also shifts its channel frequently
The
Peninsular Rivers
1.
The main water divide in
Peninsular India is formed by the Western Ghats, which runs from north to south
close to the western coast.
2.
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.
3.
There are numerous small
streams flowing west of the Western Ghats
4. The Narmada
and the Tapi are the only long rivers, which flow west and make estuaries.
The
Narmada Basin
1.
The Narmada rises in the
Amarkantak hills in Madhya Pradesh.
2.
It flows towards the west in a
rift valley formed due to faulting.
3.
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.
4.
The Narmada basin covers parts
of Madhya Pradesh and Gujarat.
The
Tapi
1.
The Tapi rises in the Satpura
ranges, in the Betul district of Madhya Pradesh.
2.
It also flows in a rift valley
parallel to the Narmada but it is much shorter in length.
3.
Its basin covers parts of
Madhya Pradesh, Gujarat and Maharashtra.
4.
The coastal plains between
Western Ghats and the Arabian Sea are very narrow.
5.
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
1. The Godavari is the largest Peninsular River.
2.
It rises from the slopes of the
Western Ghats in the Nasik district of Maharashtra.
3.
Its length is about 1500 km.
4.
It drains into the Bay of
Bengal. Its drainage basin is also the largest among the peninsular rivers.
5.
The basin covers parts of
Maharashtra (about 50 per cent of the basin area lies in Maharashtra), Madhya
Pradesh, Orissa and Andhra Pradesh.
6.
The Godavari is joined by a
number of tributaries such as the Purna, the Wardha, the Pranhita, the Manjra,
the Wainganga and the Penganga.
‘Dakshin
Ganga’
Because of its length and the area it covers, it is also known as
the ‘Dakshin Ganga’
The
Mahanadi Basin
1.
The Mahanadi rises in the
highlands of Chhattisgarh.
2.
It flows through Orissa to
reach the Bay of Bengal.
3.
The length of the river is
about 860 km. Its drainage basin is shared by Maharashtra, Chhattisgarh,
Jharkhand, and Orissa.
The
Krishna Basin
1.
Rising from a spring near
Mahabaleshwar, the Krishna flows for about 1400 km and reaches the Bay of
Bengal.
2.
The Tungabhadra, the Koyana,
the Ghatprabha, the Musi and the Bhima are some of its tributaries.
3.
Basin is shared by Maharashtra,
Karnataka and Andhra Pradesh.
The
Kaveri Basin
1.
The Kaveri rises in the
Brahmagri range of the Western Ghats and it reaches the Bay of Bengal in south
of Cuddalore, in Tamil Nadu.
2.
Total length of the river is
about 760 km.
3.
Its main tributaries are
Amravati, Bhavani, Hemavati and Kabini.
4.
Its basin drains parts of
Karnataka, Kerala and Tamil Nadu
5.
The river Kaveri makes the
second biggest waterfall in India. It is known as Sivasamudram. The fall
supplies hydroelectric power to Mysore, Bangalore and the Kolar Gold Field.
6.
71 per cent of the world’s
surface is covered with water, but 97 per cent of that is salt water. • Of the
3 per cent that is available as freshwater, three quarters of it is trapped as
ice.
LAKES
1.
Lakes of large extent are
called the seas, like the Caspian, the Dead and the Aral seas.
2.
A meandering river across a
flood plain forms cut-offsthat later develop into ox-bow lakes.
3.
Spits and bars form lagoons in
the coastal areas, eg the Chilika Lake, the Pulicat Lake, and the Kolleru Lake.
4.
Most of the fresh water lakes
are in the Himalayan region. They are of glacial origin.
5.
In other words, they formed
when glaciers dug out a basin, which was later filled with snowmelt.
6. The Wular Lake in Jammu and Kashmir, in contrast, is the result of
the tectonic activity. It is the largest freshwater lake in India.
7.
The Dal Lake, Bhimtal,
Nainital, Loktak and Barapani are some other important fresh water lakes
8.
The damming of the rivers for
the generation of hydel power has also led to the formation of Lakes such as
Guru Gobind Sagar (Bhakra Nangal Project).
9.
Lakes are of great value to
human beings. A lake helps to regulate the flow of a river.
10.
During heavy rainfall, it
prevents flooding and during the dry season, it helps to maintain an even flow
of water.
11.
Lakes can also be used for
developing hydel power
12.
They moderate the climate of
the surroundings;
13.
Maintain the aquatic ecosystem
14.
Enhance natural beauty, help develop
tourism and provide recreation
ROLE OF RIVERS
IN THE ECONOMY
1.
Rivers have been of fundamental
importance throughout the human history.
2.
The river banks have attracted
settlers from ancient times
3.
Using rivers for irrigation,
navigation, hydro-power generation is of special significance
RIVER POLLUTION
1.
The growing domestic,
municipal, industrial and agricultural demand for water from rivers naturally
affects the quality of water.
2.
As a result, more and more
water is being drained out of the rivers reducing their volume.
3.
A heavy load of untreated Sewage
and industrial effluents are emptied into the rivers.
4.
This affects not only the
quality of water but also the self-cleansing capacity of the river.
5.
Given the adequate stream flow,
the Ganga water is able to dilute and assimilate pollution loads within 20 km
of large cities.
6.
But the increasing urbanisation
and industrialisation do not allow it to happen and the pollution level of many
rivers has been rising.
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