CHAPTER 3 : Drainage System NCERT SOLUTION CLASS 11TH Indian Physical Environment | EDUGROWN NOTES

SHORT ANSWER TYPE QUESTION:

Q1. 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
Answer
(i) River Basin and Watershed

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

(ii) Dendritic and Trellis drainage pattern

Dendritic drainage pattern	Trellis drainage pattern
The drainage pattern resembling the branches of a tree is known as dendritic.	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.
The drainage pattern of Northern plain is the example of such pattern.	The drainage pattern of Himalayan mountain is the example of such pattern.

(iii) Radial and Centripetal drainage pattern

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

(iv) Delta and Estuary

Delta	Estuary
A Delta is a triangular landmass formed at the mouth of the river.	An Estuary is a funnel shaped formed at the mouth of the river.
It is formed in the regions of low tides and coastal plains.	It is formed in the regions of high tides and rift valleys.
These are extremely fertile and support agriculture.	They provide fishing ground and support inland transportation.
The rivers like Ganga and Brahmaputra form deltas.	The rivers like Narmada and Tapi form estuaries.

Q2.What are the socio-economic advantages of inter-linking of rivers in India?

Answer

The socio-economic advantages of inter-linking of rivers in India are:
• The problems of floods and drought will get solved as excess water from an area can be transferred to water deficit areas.
• The inland waterway transportation will improve which will make the transportation of materials across the country easier.
• It will also help in imporving irrigational facilities which will increase the productivity.dro-electricity and fisheries activities.

Q3. Write three characteristics of the Peninsular river.

Answer

Three characteristics of the Peninsular river are:
• These rivers originate in Peninsular plateau and central highland.
• These are seasonal and dependent on monsoon rainfall.
• These rivers are smaller having fixed course with well adjusted valleys.

Q4. What are the important characteristic features of north Indian rivers? How are these different from Peninsular rivers?

Answer

The important characteristic features of north Indian rivers are:
• They originate in Himalayan mountain covered with glaciers.
• These rivers are perennial in nature because they receive water from glacier and rainfall.
• These rivers form deep gorges and V-shaped valleys in mountainous areas.
• It has long course, flowing through the rugged mountains experiencing headward erosion and river capturing.
• These rivers are young and youthful, active and deepening in the valleys.

These are different from peninsular rivers because of these reasons:
• The north Indian rivers have very large basins while peninsular rivers have relatively smaller basin.
• The north Indian rivers are perennial as they receive water from glaciers and rainfall while peninsular rivers receive their water only from monsoon rains.
• The north Indian rivers are antecedent and consequent leading to dendritic pattern in plains while peninsular rivers are super imposed, rejuvenated resulting in trellis, radial and rectangular patterns.
• The north Indian rivers are young and youthful, active and deepening in the valleys while peninsular rivers are old with graded profile, and have almost reached their base levels.

Q5.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.

Answer

If we are travelling from Haridwar to Siliguri along the foothills of the Himalayas we will come across Gomti, Ramganga, Rapti, Gandak, Kosi, Kamla, Saryu, Sharda, Ghaghra, Mahanadi and Ganga.
The characteristics of Gandak:
• It rises in the Nepal Himalayas between the Dhaulagiri and Mount Everest and drains the central part of Nepal
• It comprises two streams, namely Kaligandak and Trishulganga
• It enters the Ganga plain in Champaran district of Bihar and joins the Ganga at Sonpur near Patna.
• Its length is 630 Km.

Long Answer Type Questions:

Q1.How are rivers of India useful for India?
Answer:
Rivers are useful for us because:

• Water: Rivers carry water and nutrients to areas all around the earth. They play a very important part in the water cycle, acting as drainage channels for surface water. Rivers drain nearly 75% of the earth’s land surface.
• Habitats: Rivers provide excellent habitat and food for many of the earth’s organisms. Many rare plants and trees grow by rivers. Ducks, voles, otters and beavers make their homes on the river banks. Reeds and other plants like bulrushes grow along the river banks. Other animals use the river for food and drink. Birds such as kingfishers eat small fish from the river.
• Delta: River deltas have many different species of wildlife. Insects, mammals and birds use the delta for their homes and for food.
• Transport: Rivers provide travel routes for exploration, commerce and recreation.

Q2.Explain about Indus River System.
Answer:
The Indus System

• It is one of the largest river basins of the world, covering an area of 11,65,000 sq. km (in India it is 321, 289 sq. km) and a total length of 2,880 km (in India 1,114 km). The Indus also known as the Sindhu, is the westernmost of the Himalayan rivers in India.
• It originates from a glacier near Bokhar Chu (31°15′ N latitude and 81°40′ E longitude) in the Tibetan region at an altitude of 4,164 m in the Kailash mountain range.
• The Indus receives a number of Himalayan tributaries such as the Shyok, the Gilgit, the Zaskar, the Hunza, the Nubra, the Shigar, the Gasting and the Dras. It finally emerges out of the hills near Attock where it receives the Kabul river on its right bank. The other important tributaries joining the right bank of the Indus are the Khurram, the Tochi, the Gomal, the Viboa and the Sangar.
• They all originate in the Sulaiman ranges. The river flows southward and receives ‘Panjnad’ a little above Mithankot. The Panjnad is the name given to the five rivers of Punjab, namely the Satluj, the Beas, the Ravi, the Chenab and the Jhelum.
• It finally discharges into the Arabian Sea, east of Karachi.
• The Indus flows in India only through the Leh district in Jammu and Kashmir.

Q3.Explain about Ganga River System.
Answer:

The Ganga System:

1. The Ganga is the most important river of India both from the point of view of its basin and cultural significance. It rises in the Gangotri glacier near Gaumukh (3,900 m) in the Uttarkashi district of Uttarakhand. Here, it is known as the Bhagirathi. It cuts through the Central
and the Lesser Himalayas in narrow gorges.

2.  At Devaprayag, the Bhagirathi meets the Alaknanda; hereafter, it is known as the Ganga. The Alaknanda has its source in the Satopanth glacier above Badrinath. The Alaknanda consists of the Dhauli and the Vishnu Ganga which meet at Joshimath or Vishnu Prayag.

3. The river has a length of 2,525 km. It is shared by Uttarakhand (110 km) and Uttar Pradesh (1,450 km), Bihar (445 km) and West Bengal (520 km). The Ganga basin covers about 8.6 lakh sq. km area in India alone.

4. The Ganga river system is the largest in India having a number of perennial and non-perennial rivers originating in the Himalayas in the north and the Peninsula in the south, respectively. The Son is its major right bank tributary.

5. The important left bank tributaries are the Ramganga, the Gomati, the Ghaghara, the Gandak, the Kosi and the Mahananda. The Yamuna, the westernmost and the longest tributary of the Ganga, has its source in the Yamunotri glacier on the western slopes of Banderpunch range (6,316 km).

6. The river finally discharges itself into the Bay of Bengal near the Sagar Island.

Q4.What factors determine volume of water in a river?
Answer:
Factors affecting the volume of water in a river:

1. An important factor affecting the volume of water in a river is the size of the drainage basin. A drainage basin in an area drained by one main river and its tributaries. If the drainage basin is large, the volume of water in the river will be more. When the drainage basin is large the surface run off flourished the river is more runoff in the amount of rainwater that flows on the ground and ultimately into the river or lake. On the other hand, if the drainage basin is small volume of water in the river will be less because there is less surface area for the rain to fall on.

2.Vegetation is also an important factor. Leaves of tress intercept rainwater and allow more water to sweep into the ground in groundwater. As a result, the amount of surface runoff reduces. Therefore, the volume of water in the river is less where vegetation is dense. Spare vegetation prevents rainwater from getting trapped in the leaves and
branches, thereby allowing more water to flow through as surface runoff. So, in areas with less vegetation volume of water is more.

3. Permeability of rocks: In area with permeable or porous rocks, much of the rainwater sweeps through the pores in the rocks into the ground. In such areas, surface run off is less and water flowing into the river channel will also be less.

4. Climate: In areas with hot and wet climate such as equatorial area, volume of water rivers will be high. However, the amount of water will be less in areas with dry climate receiving less rainfall. In areas with prominent wet or dry seasons, volume of water in the river will vary according to the amount of rainfall received.

Q5.Explain the different drainage patterns formed by rivers. Draw diagram of each drainage pattern with two examples of each.
Answer:
The drainage pattern formed by rivers are:
(a) Dendritic:
The drainage resembling, the branches of a tree is known as ‘dendritic’ the examples of which are the rivers of northern plains like Ganga, Yamuna, etc.

(b) Radial: When the rivers originate from a hill and flow in all directions, the drainage pattern is known as ‘radial’ or the dome-shaped pattern. The river originating from the Amarkanta range and central highlands present a good example of it.

(c) Trellis: When the primary tributaries of rivers flow parallel to each and secondary tributaries join them at right angles, the pattern is known as ‘trellis’ e.g. Peninsular river such as Godavari, Krishna etc.

(d)Centripetal: When the rivers discharge their waters from all directions in a lake or in depressions, it is known as ‘centrifugal’. These rivers form cascades/rapids and waterfalls.

Q6.Differentiate between:
(a) Himalayas rivers and the Peninsular rivers.
Answer:
Difference between Himalayas Rivers and the Peninsular rivers.

Aspects	Himalayan rivers	Peninsular rivers
Place of origin	Himalayan mountains covered with glaciers	Peninsular plateau and central highland
Nature of flow	Perennial; receive water from glacier and rainfall	Seasonal, dependent on monsoon rainfall
Type of drainage	Antecedent and consequent leading to dendritic pattern in plains.	Super imposed : rejuvenated resulting in trellis and rectangular pattern
Nature of river	Long course, flowing through the mountains. Experiencing headwater erosion and river capturing in plains meandering and shifting of course.	Smaller, fixed course with well adjusted valleys.
Catchment area	Very large basins	Relatively smaller basin
Area of river	Young and youthful, active and deepening of the valleys.	Old rivers with graded profile, and have almost reached their base levels
Examples	Indus, Ganges and Brahmaputra and their tributaries.	Peninsular Plateau Chambal, Betwa, Central Highlands, Godavari, Krishna, etc.

(b) Consequent rivers and Antecedent rivers
Answer:
Difference between Consequent rivers and Antecedent rivers

Basis	Consequent rivers	Antecedent rivers
Shape	These rivers maintain their original shapes, deposits, the rise of land due to folding. The rivers keep on following in the same direction.	It is an uplift area the rivers flow in the direction resulting as consequent of the slope
Age	These rivers are older than the old mountain.	These rivers are formed after the uplift of an area.

Gorges	These rivers cut deep gorges due to down cutting.	These rivers do not form gorges.
Examples	Trans- Himalayan rivers such as Indus, Satluj, represent consequent rivers.	The eastward flowing river of peninsular plateau which flow according to the slope are antecedent rivers.

Q7.Differentiate between canyon, gorge and river valley.
Answer:
A canyon is a deep valley with steep sides, think of the grand canyon most famously to visualise what this is. A gorge is a deep ravine, which usually has a river running through it—though this doesn’t have to be the case. Finally a valley is any depression, usually of a certain length, in the surface of the land and often contains a river. So, a canyon is a specific type of valley, with particularly steep sides. A gorge is a particularly deep depression, and will usually contain a river.