Lesson – 3 - Drainage
Q1.Give reason for different drainage patterns and describe the patterns?
A1.Drainage pattern depends on the slope of land, underlying rock structure, and
the climatic conditions of the area.
There are four drainage patterns:
(a)Dendritic: The dendritic pattern develops where the river channel follows the
slope of the terrain. The streams with its tributaries resembles the branches of a
tree , thus the name dendritic.
(b)Trellis :A river joined by its tributaries at approximately right angles develops a
trellis pattern. A trellis drainage pattern developes where hard and soft rocks
exist parallel to each other.
(c)Rectangular : A rectangular drainage pattern developes on a strongly jointed
rocky terrain.
(d)Radial : The radial pattern develops when streams flow in different directions
from a central peak or dome like structure.
Q2.Write down the features of the Indus river system.
A2.(a)The river Indus rises in Tibet near Lake Mansarowar . Flowing west it enters
India in the Ladakh district of Jammu and Kashmir.
(b) It forms a picturesque gorge in this part. Several tributaries , the Zaskar , the
Nubra ,the Shyok and the Hunza join it in Kashmir region.
(c)The Indus flows through Baltistan and Gilgit and emerges from the mountains
at Attock.
(d)The Sutluj, The Beas, The Ravi , The Chenab and the Jhelum join together to
enter the Indus near Mithankot in Pakistan.
(e)The Indus flow southward eventually reaching the Arabian Sea east of Karachi
in Pakistan.
(f)It has a total length of 2900 kms . Indus basin is located in India in the states of
Jammu and Kashmir , Himachal Pradesh and Punjab.
Q3.Describe the Ganga River System.
A3.a)The head waters of Ganga called the Bhagirathi is fed by the Gangotri
glaciers and joined by the Alakananda at Devaprayag in Uttarakhand.
b)At Haridwar Ganga emerges from the mountains on to the plains. The Ganga is
joined by many tributaries from the Himalayas.
c)The river Yamuna rises from the Yamunotri Glacier in the Himalayas. The
Ghaghara, the Gandak and the Kosi rises in Nepal Himalayas and join Ganga. The
main tributaries which come from the peninsular uplands are the Chambal , the
Betwa and the Son.
d)The Ganga flows eastward till Farakka in West Bengal. This is the northen most
end of the Ganga Delta.
e)The river bifurcates at Farakka The Bhagirathi –Hooghly (a distributary) flows
southward through the deltaic plains to the Bay of Bengal.
f)The length of the Ganga is over 2500Km.
g)Ambala is located on the water divide between the Indus and the Ganga river
system.
Q4.Describe the course of Brahmaputra river.
A4.a)The Brahmaputra rises in Tibet east of Manasrowar lake very close to the
sources of the Indus and the Sutluj.
b)It is slightly longer than the Indus and the most of its course lies outside India.It
flows eastward parallel to the Himalayas .On reaching the Namcha Barwa
(7757m) it takes a “U” turn and enters India.
c)In Arunachal Pradesh it is called the Dihang and it is joined by the Dibang ,the
Lohit and many other tributaries.
d)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. Here the river carries a
large volume of water and considerable amount of silt.
e)The Brahmaputra has a braided channel in its entire length in Assam and forms
many riverine islands. The river also shifts its channels frequently.
f)Every year during the rainy season the river overflows its banks causing
widespread devastation due to floods in Assam and Bangladesh.
Q5.Differentiate between Himalayan rivers and Peninsular rivers.
A5.
Himalayan Rivers
a)Most of the Himalayan rivers are
perennial .It means they have water
throughout the year. These rivers
receives water from rain as well as from
melted snow from the lofty mountains.
b)The Himalayan rivers have long
course from their source to the
sea.Drainage basins are larger
c)they perform intensive erosional
activities in their upper courses and
carry huge loads of silt and sand
d)These rivers form big deltas
e)They flow in leveled Northern Plains
and are highly useful for irrigation,
cultivation and also for navigation
Peninsular Rivers
A large number of 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
swallower courses. Their drainage
basins are comparatively smaller.
They perform less erosional activity in
comparision.
The peninsular rivers forms
comparatively small deltas.
They flow on rocky surface and so they
are neither navigable nor useful for
irrigation
Q6.Compare the East flowing rivers and the West flowing rivers in Peninsula.
A6.
East flowing rivers
a)They drain into the Bay of Bengal
b)These rivers have longer courses
c)These rivers forms extensive deltas on
the east coast
d)Major rivers are Godavari,Mahanadi
,Krishna,Kaveri
e)These rivers have a developed large
tributary system
West flowing rivers
They drain into the Arabian Sea
These rivers have shorter courses
These do not form deltas that form
estauries
Major rivers are Narmada ,Tapi
These are devoid of developed tributary
system. Their tributaries are small in
size.
Q7.Where do the following rivers rise and where do they drain?
A7.
River
1.Narmada
2.Tapi
3.Godawari Basin
4.Mahanadi
5.Krishna
6.Kaveri
Source
Rises in the Amarkantak
hills in the Madhya
Pradesh
Rises in the Satpura
Ranges in the Betul
district of MP
Rises in the slopes of the
Western Ghats in the
Nasik district of
Maharashtra
Rises in the highlands of
Chattisgarh in Raipur
district
Rises from a spring near
Mahabaleshwar in
Maharashtra
Rises in the Brahmagri
range of the Western
Ghats
Drain into
Arabian Sea
Arabian Sea
Bay of Bengal
Bay of Bengal
Bay of Bengal
Bay of Bengal
Q8.Where are the drainage basins of the following rivers?
A8.
Rivers
1.Narmada
2.Tapi
3.Godavari
4.Mahanadi
5.Krishna
6.Kaveri
States
Madhya Pradesh,Gujrat
Madhya Pradesh,Gujrat ,Maharashtra
Maharashtra, MP, Orissa , Andhra
Pradesh
Maharashtra, Chhattisgarh, Jharkhand,
Orissa
Maharashtra, Karnataka , Andhra
Pradesh
Karnataka , Kerala Tamil Nadu.
Q9.Why are the rivers of India so polluted? What has the government done to
clean the Ganga?
A9.The cause of river pollution are:
1.The growing domestic,municipal,industrial and agricultural demand for water
form rivers effects the quality of water. As a result more and more water is being
drained out of rivers reducing their volume.
2.A heavy load of untreated sewage from the cities pollutes the river.
3.Industrial effluents are emptied into the rivers. This effects not only the quality
of water but also the self-cleansing capacity of the river.
The steps taken by the Government to clean the river Ganga are:
1.The National River Conservation Authority looks after the state of the rivers in
India.
2.The Government launched the Ganga Action Plan (GAP) Phase-I in 1983 to clean
up the river Ganga. This was closed in 2000.
3.The Ganga Action Plan phase-II has been merged with (NRCP) National River
Conservation Plan now cover 152 towns in 16 States.
4.Under this action plan pollution abatements works are being fallen taken up in
57 towns
5.A total of 215 schemes of pollution abatment have been sanctioned .69
schemes have been completed so far under this action plan.
Q10.Why are rivers important for the country’s economy? Or
Discuss the uses of rivers?
A10.Rivers are highly important for country’s economy.
a)They make soil rich and fertile.
b)The river banks have attracted settlers from ancient time. These settlements
have now become big cities.
c)They are used for developing hydel power.
d)They prevent flood during heavy rainfall.
e)They moderate the climate of the surroundings.
f)They help to develop tourism and provide recreation.
g) Rivers are used for irrigation and navigation.
Q11.Why are peninsular rivers not navigable?
A11.Peninsular rivers are not navigable because a large number of peninsular
rivers are seasonal. The flow of peninsular rivers are dependent upon rainfall and
they generally get dried up in the summer. The river beds are uneven , rocky and
have sharp slopes. Construction of dams have also made navigation difficult.
Q12. Describe the features of any two peninsular rivers.
A12.Godavari Basin.
(i)The Godavari in the largest peninsular river.
(ii)It rises from the slopes of the Western Ghats in the Nasik district of
Maharashtra.
(iii)Its length is about 1500Km.
(iv)It drains into the Bay of Bengal
(v)Its drainage basin is the largest among the peninsular rivers. It covers parts of
Maharashtra, Madhya Pradesh, Orissa and Andhra Pradesh.
(vi)Its tributaries are the Purna, the Wardha, the Pranhita, the Manjra, the
Wainganga and the Penganga.
(vii)It is known as the Dakshin Ganga due to its length and the area it covers.
Narmada Basin.
(i)The Narmada rises in the Amarkantak hills in Madhya Pradesh.
(ii)It flows towards the west in a rift valley formed due to faulting.
(iii)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
locations created by the Narmada.
(iv)The Narmada basin covers parts of Madhya Pradesh and Gujarat.
Tapi Basin
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. The Coastal plains between Western Ghats and the Arabian Sea are very
narrow. Hence, the Coastal rivers are short.
4. The main west flowing rivers are Sabarmati, Mahi, Bharathpujha and
Periyar.
Q13.What are the features of Himalayan Rivers?
A13.(i)Most of the Himalayan rivers are perennial .They have water throughout
the year .These rivers receive water from rain as well as from melted snow from
the lofty mountains.
(ii)They flow through narrow gorge like valleys with steep slopes.
(iii)They perform intensive erosion activities in their upper course and carry huge
silt and sand.
(iv)Drainage basin of the Himalayan rivers are large.
(v)In the middle and the lower courses ,the Himalayan rivers form the meanders,
ox bow lakes and many other depositional features in their flood plains.
(vi)They also have well developed deltas.
Q14.What are the features of the peninsular rivers?
A14.(i)A large number of peninsular rivers are seasonal as their flow is dependent
on rainfall. During dry season even the large rivers have reduced flow of water .
(ii)The peninsular river flow through open , shallow valley’s.
(iii)Their intensity of erosional activity is less due to the gentler slope.
(iv) They have shorter and shallower courses.
(v) Most of the rivers of peninsular India originate in the Western Ghats and flow
towards the Bay of Bengal.
Q15.Why does Brahmaputra in its Tibetian part have less silt despite a longer
course?
A15.In Tibet , the Brahmaputra river carries a smaller volume of water and less silt
as it is cold and 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.
Q16.Classify Lakes in three categories and also give examples.
A16.1.Fresh Water Lakes: They are mainly found in Himalayan region. They are of
glacial region. They are formed when glaciers dug out a basin , which are later
filled with snowmelt.The Wular lake is the largest fresh water lake of India. The
Dal lake, Bhimtal, Nainital ,Loktak are also examples of fresh water lakes.
2. Salt water lakes : They are mainly found in Rajasthan. The Sambhar lake in the
desert region is a salt water lake. Its water is used for producing salt.
3. Lagoon:- It is shallow body of water separated from sea by a narrow strip of
land or by a sand bar. The Chilka lake and the Pulicat lake near Chennai are
examples of lagoons.
Q17. Describe the importance of lakes to man?
Answer discussed in class.