CHAPTER 3 Drainage

Question 1: Which one of the following describes the drainage patterns resembling the branches of a tree?

(i) (b) Dendritic

Question 2: In which of the following states is the Wular lake located?

(ii) (d) Jammu and Kashmir

Question 3: The river Narmada has its source at

(iii) (c) Amarkantak

Question 4: Which one of the following lakes is a saltwater lake?

(iv) (a) Sambhar

Question 5: Which one of the following is the longest river of Peninsular India?

(v) (c) Godavari

Question 6: Which one amongst the following rivers flows through a rift valley?

(vi) (d) Tapi

Q2 Answer the following questions briefly

Question 1: What is meant by a water divide? Give an example.

(i) Any elevated area such as a mountain or an upland that separates two drainage basins is called a water divide. An example is the Western Ghats.

Question 2: Which is the largest river basin in India?

(ii) The Ganga Basin is the largest river basin in India.

Question 3: Where do the rivers Indus and Ganga have their origin?

(iii) The river Indus rises in Tibet, near lake Mansarovar, and the Ganga originates at the Gangotri Glacier. Both of them have their origin in the Himalayas.

Question 4: Name the two headstreams of the Ganga. Where do they meet to form the Ganga?

(iv) The two headstreams of the Ganga are the Bhagirathi and Alaknanda. They meet at Devprayag in Uttarakhand to form the Ganga.

Question 5: Why does the Brahmaputra in its Tibetan part have less silt, despite a longer course?

(v) In Tibet, the river Indus, known as Tsang Po, carries a smaller volume of water and less silt as it is a cold and dry area. In India, the river carries a large volume of water and a considerable amount of silt because it passes through a region of high rainfall.

Question 6: Which two Peninsular rivers flow through a trough?

(vi) Narmada and Tapi are two peninsular rivers that flow through a trough.

Question 7: State some economic benefits of rivers and lakes.

(vii) Lakes have several economic benefits:

  • Lakes help regulate the flow of rivers.
  • They prevent flooding during the rainy season.
  • Lakes maintain an even flow of water during the dry season.
  • Lakes can be used for developing hydel power.
  • They moderate the climate of the surroundings and maintain the aquatic ecosystem.
  • Lakes enhance natural beauty, help develop tourism, and provide recreation. Examples include Dal Lake and Naini Lake at Nainital.

Q3 Below are given names of a few lakes of India.

Question 3: Group the following lakes of India into natural and manmade categories.

Natural Lakes:

  • Wular
  • Dal
  • Nainital
  • Bhimtal
  • Loktak
  • Barapani
  • Chilka
  • Sambhar
  • Pulicat

Manmade Lakes:

  • Gobind Sagar
  • Rana Pratap Sagar
  • Nizam Sagar
  • Nagarjuna Sagar
  • Hirakud

Question 4: Discuss the significant differences between Himalayan and Peninsular rivers.

Himalayan Rivers:

  • Perennial flow throughout the year.
  • Receive water from rainfall and melting snow of the mountains and glaciers.
  • Long courses.
  • Carry a lot of silt and sand.
  • Originate from the North of the Himalayan mountain ranges.
  • Drainage basins are large.
  • Form big deltas.
  • Useful for irrigation, cultivation, and navigation.

Peninsular Rivers:

  • A large number are seasonal, flowing during a certain period.
  • Receive water mainly from rainfall.
  • Short and shallow courses.
  • Carry very little or no silt and sand.
  • Mainly originate in the Western Ghats.
  • Drainage basins are small.
  • Form small deltas.
  • Seasonal, flow over rocky areas, not useful for cultivation and navigation.

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

East Flowing Rivers:

  • Originate from the Western Ghats and flow eastwards.
  • Flow into the Bay of Bengal.
  • Form deltas at their mouths.
  • Carry a larger amount of water.
  • Examples: Mahanadi, Godavari, Krishna, and Kaveri.

West Flowing Rivers:

  • Originate in central India and flow westwards.
  • Flow into the Arabian Sea.
  • Form estuaries at their mouths.
  • Carry a lesser amount of water.
  • Examples: Narmada and Tapi.

Question 6: Explain why rivers are important for the country's economy.

Rivers are crucial for the country's economy because:

  • They provide water for irrigation.
  • They enhance soil fertility.
  • They facilitate navigation.
  • They contribute to hydro-electricity generation.
  • They promote tourism.
  • They supply water for various domestic uses.
  • They support the livelihood of fishermen.
  • They play a role in moderating the climate and environment of nearby areas.
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