Drainage – Chapter 3 Geography Class 9 NCERT Solutions

1. Choose the right answer from the four alternatives given below.

(i) Which one of the following describes the drainage patterns resembling the branches of a tree?

(a) Radial (b) Dendritic (c) Centrifugal (d) Trellis

(ii) In which of the following states is the Wular lake located?

(a) Rajasthan (b) Uttar Pradesh (c) Punjab (d) Jammu and Kashmir

(iii) The river Narmada has its source at

(a) Satpura (b) Brahmagiri (c) Amarkantak (d) Slopes of the Western ghats

(iv) Which one of the following lakes is a salt water lake?

(a) Sambhar (b) Dal (c) Wular (d) Gobind Sagar

(v) Which one of the following is the longest river of the Peninsular India?

(a) Narmada (b) Krishna (c) Godavari (d) Mahanadi

(vi) Which one amongst the following rivers flows through a rift valley?

(a) Damodar (b) Tungabhadra (c) Krishna (d) Tapi

2. Answer the following questions briefly.

(i) What is meant by a water divide? Give an example.

Ans. Any elevated area separates two drainage basins. Such upland is called a water divide. Example: Ambala is located on the water divide between The Indus and The Ganga.

(ii) Which is the largest river basin in India?

Ans. The Ganga River Basin is the largest river basin in India

(iii) Where do the rivers Indus and Ganga have their origin?

Ans. The Indus river has its origin in Tibet near the Mansarovar Lake where as the Ganga River originates from the Gangotri Glacier in Uttaranchal.

(iv) Name the two headstreams of the Ganga. Where do they meet to form the Ganga?

Ans. Bhagirathi and Alaknanda are the two headstreams of river Ganga. Both Bhagirathi and Alaknanda meet at Devaprayag to form the Ganga.

(v) Why does the Brahmaputra in its Tibetan part have less silt, despite a longer course?

Ans. The Brahmaputra river is popularly known as Tsangpo in Tibetan part. Tibet is basically a very cold and dry area, thus, the river carries very small amount of water leading to very less silt content, despite having a large course.

(vi) Which two Peninsular rivers flow through trough?

Ans. Narmada and Tapi are the two peninsular rivers flowing through the trough.

(vii) State some economic benefits of rivers and lakes.

Ans. Economic benefits of rivers:-

1. Rivers have been a source of food since pre-history, almost all the civilizations developed along the river banks.

2. Rivers are also used for irrigation, hydro-power generation.

3. Rivers are used for navigation. They provide the cheapest inland means of transport.

4. Water from the river is the basic natural resource essential for various day-to-day activities of human beings.

5. It is also a rich source of fresh water fish.

Benefits of a Lake:

1. A lake helps in preventing flood by regulating the flow of river.

2. During dry seasons, a lake helps to maintain an even flow of the river.

3. Lakes can also be used for generating hydel power.

4. Tourism development.

5. Maintain aquatic ecosystem.

3. Below are given names of a few lakes of India. Group them under two categories – natural and created by human beings.

Ans. Natural Lakes:- Wular, Dal, Nainital, Bhimtal, Loktak, Barapani, Chilika, Sambhar, Pulicat.

Man-made Lakes:- Gobind Sagar, Rana Pratap Sagar, Nizam Sagar, Nagarjuna Sagar, Hirakund.

4. Discuss the significant difference between the Himalayan and the Peninsular rivers.

Ans. Himalayan Rivers:-

  1. These rivers are perennial in nature.
  2. Being in a hilly Rocky Terrain these rivers cause much erosion and have great flow of water.
  3. These rivers meander .
  4. These rivers originate in the Himalayas due to melting of snow and Glacier.
  5. The Himalayan rivers flow towards the northern plains and a very helpful in irrigation.
  6. They make the Northern plains fertile.
  7. The Ganga, the Indus and Brahmaputra river are the major Himalayan rivers.

Peninsular Rivers:-

  1. Peninsular rivers are seasonal in nature they diminish in summer and replenish in monsoon.
  2. These rivers create less erosion and they have weaker flow of water.
  3. Peninsular rivers do not meander much, they are usually straight.
  4. These rivers originate in small hills and plateaus.
  5. These rivers are an essential part of Deccan Plateau’s irrigation projects.
  6. These rivers cover shorter distance before draining into the Arabian Sea or Bay of Bengal.
  7. Narmada, Tapi, Mahanadi, Godavari, Krishna and Kaveri are the major peninsular rivers.

5. Compare the east flowing and the west flowing rivers of the Peninsular plateau.

Ans. West flowing peninsular rivers:-

  1. Narmada and Tapi are the main west flowing peninsular rivers.
  2. These rivers drain into the Arabian Sea.
  3. These rivers make estuaries.
  4. The tributaries of West flowing peninsular rivers are quite small in size.
  5. West flowing peninsular rivers flow in channels.

East flowing peninsular rivers:-

  1. Mahanadi, Godavari, Krishna and Kaveri are the main east flowing peninsular rivers.
  2. These rivers drain into the Bay of Bengal.
  3. These rivers make deltas.
  4. These rivers have a developed, large tributary system.
  5. East flowing rivers do not flow through very deep canals.

6. Why are rivers important for the country’s economy?

Ans. Rivers are the main source of water for irrigation and agricultural purposes. And if you see India is an agrarian country where farming is the largest occupation of the people. Hence, rivers in India play an important role for not just supplying water, but also for transporting goods and people from one place to another. Basically river plays a role of in the supply chain and it is very evident if we looked at many multipurpose projects that are being built on most of the major rivers in India.

Some of the economical benefits of rivers are:-

1. River the used for irrigation, navigation, hydro power generation which is economically beneficial for any country.

2. Rivers are used for navigation. They provide the cheapest inland means of transport.

3. Rivers are a rich source of freshwater fish, therefore the entire fishery industry depends on rivers.

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