Drainage System

Questions and Answers | Class 11 | Indian Physical Environment | Chapter 3 | AHSEC

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

(i) Which one of the following rivers was known as the “Sorrow of Bengal”?

(a) The Gandak

(b) The Son

(c) The Koci

(d) The Damodar

(ii) Which one of the following rivers has the largest river basin in India?

(a) The Indus

(b) The Brahmaputra

(c) The Ganga

(d) The Krishna

(iii) Which one of the following rivers is not included in “Panchnad’?

(a) The Ravi

(b) The Chenab

(c) The Indus

(d) The Jhelum

(iv) Which one of the following rivers flows in a rift valley?

(a) The Son

(b) The Narmada

(c) The Yamuna

(d) The Luni

(v) Which one of the following is the place of confluence of the Alakananda and the Bhagirathi?

(a) Vishnu Prayag

(b) Rudra Prayag

(c) Karan Prayag

(d) Deva Prayag

2. State the differences between the following.

(i) River Basin and Watershed

River Basin	Watershed
The catchments of large rivers are called river basins. River basins are larger in area.	Catchments of small rivulets and rills are often referred to as watersheds. Watershed are smaller in area.

(ii) Dendritic and Trellis Drainage Pattern

Dendritic drainage pattern	Trellis drainage pattern
The drainage pattern that resembles the branches of a tree is known as ‘dendritic’. Example is drainage pattern of Northern plain.	When the primary tributaries of rivers flow parallel to each other and secondary tributaries join them at right angles, the pattern is known as ‘trellis’. Example is drainage pattern of Himalayan mountains and the eastern ranges.

(iii) Radial and Centripetal Drainage Pattern

Radial drainage pattern	Centripetal drainage pattern
When the rivers originate from a hill and flow in all directions, then the drainage pattern is known as radial. The rivers originating from the Amarkantak range is a good example of this.	When the rivers discharge their waters from all directions into a lake or depression, the pattern is known as ‘centripetal’. Sambhar Lake of Rajasthan is the good example of it.

(iv) Delta and Estuary

Delta	Estuary
It is a triangular land mass formed by depositional alluvium at the mouth of river. They are rich agriculture ground. Rivers like Kaveri, Krishna, Mahanadi and Godavari form deltas.	It is the sunken mouth of the river where the river meets the sea forming the tunnel shaped zone where saline and fresh water mix. They are rich fishing ground and are suitable for inland transportation. Narmada and Tapti form estuaries.

3. Answer the following questions in about 30 words.

(i) What are the socio-economic advantages of inter-linking of rivers in India?

Indian rivers are of two types – Perennial rivers in which water is there throughout the year and Peninsular rivers in which water is there in rainy seasons only. Rivers of India bear a large amount of water every year. But with respect to time and place, its distribution is uneven. Most of the water gets wasted in the floods during rainy seasons. It also causes loss of life and property. It damages agriculture as well. In some places, drought occurs.

Therefore, if the rivers are connected through canals, then the problems of floods and droughts will get solved. It will also solve the problem of drinking water and millions of rupees will be saved. It will improve the economic condition of farmers by increasing their productivity.

(ii) Write 3 characteristics of the Peninsular rivers.

• These rivers originate in peninsular plateau and central highland. These are smaller rivers having fixed course with well-adjusted valleys.
• These are seasonal as they depend on monsoon rainfall.
• They reflect superimposed type of drainage pattern and rejuvenated resulting in trellis, radial and rectangular patterns.