Exercise Solution
1. Choose the right answer from the four
alternatives given below.
(i) In which of the following states is the Wular lake
located?
(a) Rajasthan (c) Punjab
(b) Uttar Pradesh (d) Jammu and Kashmir
Answer
– (d) Jammu and Kashmir
Note – Most of the freshwater lakes are in the Himalayan region.
They are of glacial origin. In other words, they formed when glaciers dug out a
basin, which was later filled with snowmelt. The Wular lake in Jammu and Kashmir, in contrast, is the result of tectonic activity.
It is the largest freshwater lake in
India. The Dal lake, Bhimtal, Nainital, Loktak and Barapani are some other
important freshwater lakes.
(ii)
The river Narmada has its source at
(a) Satpura (c) Amarkantak
(b)
Brahmagiri (d) Slopes of the Western Ghats
Answer
– (c) Amarkantak
Note – 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. 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.
(iii) Which one of the following lakes is a
salt water lake?
(a) Sambhar (c) Wular
(b) Dal
(d) Gobind Sagar
Answer
– (a) Sambhar
Note - Lakes
in the region of inland drainage are sometimes seasonal; for example, the Sambhar lake in Rajasthan, which is
a salt water lake. Its water is used for producing salt. These lakes’ water is
not suitable for drinking but it is used for some of domestic activities like
cloth washing and cleaning the house. For irrigation purpose it is used in
farming process.
(iv) Which one of the following is the
longest river of the Peninsular India?
(a) Narmada (c) Godavari
(b)
Krishna (d) Mahanadi
Answer
– (c) Godavari
Note - 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 Wainganga 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.
(v) Which one amongst the following rivers
flows through a rift valley?
(a) Mahanadi (c) Krishna
(b)
Tungabhadra (d) Tapi
Answer
– (d) Tapi
Note - 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.
2. Answer the following questions briefly.
(i) What is meant by a water divide? Give
an example.
Answer
– The term drainage describes
the river system of an area. The area drained by a single river system is
called a drainage basin.
Any elevated area, such as a mountain or an upland, separates two drainage
basins is known as a water divide. For
example: Ambala in Haryana is located on the water divide between the Indus and
the Ganga river systems.
(ii) Which is the largest river basin in
India?
Answer – The Ganga River System is the largest river basin
in India. 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.
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.
(iii) Where do the rivers Indus and Ganga
have their origin?
Answer
– Indus
and Ganga both of them have their origin in the Himalayas, the river Indus raises
near the Mansarovar Lake in Tibet and the Ganga originates at the Gangotri
glacier in the Himalayas. The Indus flows through Baltistan and Gilgit and
emerges from the mountains at Attock and the headwaters the Ganga, called
Bhagirathi is fed by the Gangotri Glacier and joined by the Alaknanda at
Devaprayag in Uttarakhand.
(iv) Name the two headstreams of the
Ganga. Where do they meet to form the Ganga?
Answer
– Bhagirathi and Alaknanda are the two headstreams of the Ganga. Bhagirathi
is fed by the Gangotri Glacier and joined by the Alaknanda and by passing from
here it meets at Devaprayag in Uttarakhand.
(v) Why does the Brahmaputra in its Tibetan
part have less silt, despite a longer course?
Answer
– 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 flow 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.
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. Majauli, the world’s largest
riverine island formed by the Brahmaputra in Assam. Every year during the rainy
season, the river overflows its banks, causing widespread devastation due to
floods in Assam and Bangladesh. Brahmaputra is known
as the Tsang Po in Tibet and Jamuna in Bangladesh.
(vi) Which two Peninsular rivers flow
through trough?
Answer
– The Narmada and the Tapi are the only two long rivers, which
flow through trough, which flow west and make estuaries.
(vii) State some economic benefits of
rivers and lakes.
Answer – There are some economic benefits of rivers and lakes
mentioned below:
Economic benefits of rivers:
(a) In a country like
India where agriculture is dependent on the monsoons, then in that case these
rivers provide water for the irrigation and domestic purposes as well.
(b) Rivers carry slit
and sediment which make the land fertile by carrying all the waste along with it
and provide the most productive agricultural lands in the country.
(c) It also dilutes
and transport wastes from settlements.
(d) Because of the
help of rivers the development of industries has been flourished along rivers
as many industrial processes rely on water as a raw material and for generation
of hydroelectricity.
(e) Rivers are helpful
in providing means of transport and inland waterways.
(f) Rivers have been
of fundamental importance throughout the human history and because of it
recreation, tourist promotion and fishing are also being developed along
waterfronts.
Economic benefits of lakes:
(a) Lakes are also of great to human beings. It helps in regulating the flow of
a river.
(b) Lakes prevent
flooding during heavy rainfall.
(c) It helps in
maintaining an even flow of water during dry season.
(d) It helps in
moderating the climate of surrounding areas.
(e) It helps in
maintaining the aquatic ecosystem.
(f)
It also helps in developing tourism and providing recreation because of
enhancement of natural beauty due to increasing number of lakes.
3. Below are given names of a few lakes of
India. Group them under two categories – natural and created by human beings.
(a)
Wular (b) Dal (c) Nainital (d) Bhimtal (e) Gobind Sagar (f) Loktak (g) Barapani
(h) Chilika (i) Sambhar (j) Rana Pratap Sagar (k) Nizam Sagar (l) Pulicat (m)
Nagarjuna Sagar (n) Hirakund
Answer
–
Natural Lakes – (a)
Wular (b) Dal (c) Nainital (d) Bhimtal (f) Loktak (g) Barapani (h) Chilika (i)
Sambhar (l) Pulicat
Artificial Lakes (Created by Human Beings) - (e)
Gobind Sagar (j) Rana Pratap Sagar (k) Nizam Sagar (m) Nagarjuna Sagar (n)
Hirakund
Note - Apart from natural
lakes, the damming of the rivers for the generation of hydel power has also led
to the formation of lakes as Guru Gobind Sagar (Bhakra Nangal Project).
4. Discuss the significant difference
between the Himalayan and the Peninsular Rivers.
Answer
– 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.
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.
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.
5. Compare the east flowing and the west
flowing rivers of the Peninsular plateau.
Answer
– 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.
(a)
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.
(b)
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.
6. Why are rivers important for the
country’s economy?
Answer – Rivers are important in many ways for the country’s
economy; few of them are discussed below:
(a) As we all know
that India is a country where agriculture is the major source of livelihood of
the majority of its population and for agriculture water is the vital source.
(b) It carries silt
and sediment which make the flood plains fertile and along this provide the
most productive agricultural lands in the country.
(c) These rivers also
dilute and transport wastes from settlements.
(d)
Rivers have been helpful in development of industries as many industrial
processes rely on water as a raw material.
(e) It also provides means of transport and inland waterways.
(f) Rivers make the country naturally beautiful which attracts tourists and many kind of employment is also provided like fishing.