Drainage SystemClass 11 India Physical Environment NCERT Solutions
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Solution 1 of 5
Q1EXERCISES_
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 Kosi
(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 Alaknanda and the Bhagirathi?
(a)
Vishnu Prayag
(b)
Rudra Prayag
(c)
Karan Prayag
(d)
Deva Prayag
Solution
(i)
(d) The Damodar - The text states, "Once known as the 'sorrow of Bengal', the Damodar has been now tamed by the Damodar Valley corporation, a multipurpose project."
(ii)
(c) The Ganga - According to the source, "The Ganga basin covers about 8.6 lakh sq. km area in India alone. The Ganga river system is the largest in India..."
(iii)
(c) The Indus - The text defines the Panjnad as "the name given to the five rivers of Punjab, namely the Satluj, the Beas, the Ravi, the Chenab and the Jhelum." The Indus is the main river that the Panjnad joins, but it is not part of the group of five rivers.
(iv)
(b) The Narmada - The text describes the Narmada as "Flowing in a rift valley between the Satpura in the south and the Vindhyan range in the north..."
(v)
(d) Deva Prayag - As mentioned in the chapter, "At Devprayag, the Bhagirathi meets the Alaknanda; hereafter, it is known as the Ganga."
Q2EXERCISES_
State the differences between the following.
(i)
River Basin and Watershed
(ii)
Dendritic and Trellis drainage pattern
(iii)
Radial and Centripetal drainage pattern
(iv)
Delta and Estuary
Solution
(i) River Basin and Watershed
- River Basin: A river basin, also called a drainage basin, is a large area of land drained by a major river and its tributaries. For example, the Ganga basin includes the area drained by the Ganga and all its tributaries like the Yamuna, Ghaghara, and Son.
- Watershed: A watershed is also an area of land that drains into a common water body, but it typically refers to a much smaller area, such as that of small rivulets and rills. The boundary separating one drainage basin from another is also known as a watershed. In essence, the main difference is one of scale: basins are large, while watersheds are small.
(ii) Dendritic and Trellis drainage pattern
- Dendritic Pattern: This drainage pattern resembles the branches of a tree. It develops where the river channel follows the slope of the terrain. The tributaries join the main river at acute angles. The rivers of the northern plains are good examples of this pattern.
- Trellis Pattern: This pattern develops in regions of parallel, elongated landforms. The primary tributaries flow parallel to each other, and the secondary tributaries join them at right angles, creating a trellis-like appearance.
(iii) Radial and Centripetal drainage pattern
- Radial Pattern: In a radial pattern, rivers originate from a central high point, like a hill or volcano, and flow outwards in all directions. The rivers originating from the Amarkantak range are a good example of this pattern.
- Centripetal Pattern: This is the opposite of the radial pattern. In a centripetal pattern, rivers flow from all directions into a central depression or a lake. The water is collected in a central basin.
(iv) Delta and Estuary
- Delta: A delta is a triangular-shaped depositional feature formed at the mouth of a river where it enters a sea or ocean. It is formed by the deposition of sediments carried by the river. The Ganga-Brahmaputra delta is a prominent example.
- Estuary: An estuary is a deep, funnel-shaped valley at the mouth of a river where freshwater from the river mixes with saltwater from the sea. They are formed where rivers flow through rift valleys and do not carry a large load of sediment. The Narmada and Tapi rivers form estuaries where they meet the Arabian Sea.
Q3EXERCISES_
Answer the following questions in about 30 words.
(i)
What are the socio-economic advantages of inter-linking of rivers in India?
(ii)
Write three characterstics of the Peninsular river.
Solution
(i) What are the socio-economic advantages of inter-linking of rivers in India?
The primary socio-economic advantage of inter-linking rivers is the mitigation of regional imbalances in water availability. It aims to transfer surplus water from flood-prone areas to water-deficit and drought-prone regions. This can help in controlling floods, reducing droughts, increasing the area under irrigation, providing water for drinking and industrial purposes, and improving inland navigation.
(ii) Write three characterstics of the Peninsular river.
Three main characteristics of the Peninsular rivers are:
- Fixed Course: They flow through hard, rocky terrain, which results in well-defined, fixed courses with very few meanders.
- Non-Perennial Flow: These rivers are rain-fed, and their flow is dependent on monsoon rainfall. Therefore, they have a reduced flow of water during the dry season.
- Mature Valleys: The Peninsular drainage system is older than the Himalayan system, which is evident from their broad, largely-graded, and shallow valleys.
Q4EXERCISES_
Answer the following questions in not more than 125 words.
(i)
What are the important characteristic features of north Indian rivers? How are these different from Peninsular rivers?
(ii)
Suppose you are travelling from Haridwar to Siliguri along the foothills of the Himalayas. Name the important rivers you will come across. Describe the characteristics of any one of them.
Solution
(i) What are the important characteristic features of north Indian rivers? How are these different from Peninsular rivers?
North Indian rivers, also known as Himalayan rivers, originate from the snow-capped Himalayan mountains. Their key features include:
- Perennial Flow: They are fed by both melting snow and precipitation, ensuring a continuous flow of water throughout the year.
- Youthful Stage: In their mountainous course, they flow through deep gorges, V-shaped valleys, and form rapids and waterfalls, indicating a youthful and erosional stage.
- Depositional Features: Upon entering the plains, they form extensive depositional features like floodplains, ox-bow lakes, braided channels, and large deltas at their mouths. They have a strong meandering tendency and often shift their courses.
These rivers differ significantly from Peninsular rivers:
| Feature | Himalayan Rivers (North Indian) | Peninsular Rivers |
|---|---|---|
| Origin | Himalayan glaciers and ranges | Peninsular plateau and central highlands |
| Nature of Flow | Perennial (snow-fed and rain-fed) | Non-perennial/Seasonal (mostly rain-fed) |
| Course | Long courses, meandering in plains | Shorter and shallower courses, mostly straight |
| Drainage Basin | Very large basins | Comparatively smaller basins |
| Valley Type | Deep gorges, V-shaped valleys | Broad, shallow, and graded valleys |
| Age | Young and in an active stage of erosion | Old rivers with a mature profile |
(ii) Suppose you are travelling from Haridwar to Siliguri along the foothills of the Himalayas. Name the important rivers you will come across. Describe the characteristics of any one of them.
Traveling from Haridwar in the west to Siliguri in the east along the Himalayan foothills would involve crossing several major rivers that flow down from the mountains to the Gangetic plain. The important rivers encountered on this journey, in order from west to east, would be the Ramganga, Gomati, Ghaghara, Gandak, Kosi, and finally the Mahananda near Siliguri.
Characteristics of the Kosi River:
The Kosi is an antecedent river, meaning it has maintained its course despite the uplift of the Himalayas. Its source is north of Mount Everest in Tibet. The river is notorious for its destructive nature and is often called the 'sorrow of Bihar'. This is because it brings a huge quantity of sediment from its upper reaches and deposits it in the plains. This deposition blocks its course, causing the river to frequently and drastically change its path, leading to devastating floods over vast areas. In Nepal, after its main stream Arun is joined by the Son Kosi and Tamur Kosi, it is known as the Sapt Kosi.
Q1Project/Activity
Study the Appendix III and answer the following questions.
(i)
Which river has the largest proportion of catchment area in the country?
(ii)
Make a comparative bar diagram on a graph paper to show the length of the courses of the rivers.
Solution
(i) Which river has the largest proportion of catchment area in the country?
Based on the information provided in the chapter, the Ganga river has the largest river basin and catchment area in India. The text explicitly states, "The Ganga basin covers about 8.6 lakh sq. km area in India alone. The Ganga river system is the largest in India...".
(ii) Make a comparative bar diagram on a graph paper to show the length of the courses of the rivers.
This is a practical activity that requires creating a bar diagram. The data for the diagram can be sourced from the chapter, which provides the lengths of major Indian rivers. A bar diagram would visually represent these lengths for easy comparison.
Data for the bar diagram from the chapter:
- Indus: 2,880 km (1,114 km in India)
- Ganga: 2,525 km
- Godavari: 1,465 km
- Krishna: 1,401 km
- Narmada: 1,312 km
- Chenab: 1,180 km
- Mahanadi: 851 km
- Kaveri: 800 km
- Tapi: 724 km
To create the diagram, one would draw a horizontal axis (X-axis) for the names of the rivers and a vertical axis (Y-axis) for the length in kilometers. A rectangular bar would be drawn for each river, with its height corresponding to its length on the vertical axis.