CBSE Class 9 - Social Science - Geography - Chapter Drainage (Q and A) (#cbseNotes)

Drainage (Q and A)

CBSE Class 9 - Geography Notes

Question: Name the four groups of river systems found in India?

Answer:

① Himalayan rivers,
② Deccan rivers,
③ Coastal rivers and
④ Rivers of the inland drainage basin.


Question: Distinguish between rivers of the North and South of India.

Answer:  See answer in this post (Drainage -Peninsular and Himalayan rivers.)




Question: Name the different drainage patterns formed by the streams.

Answer: The streams within a drainage basin form certain patterns, depending on the slope of the land, rock structure and the climatic conditions of the area.

Drainage patterns are divided into four categories:

① Dendrite pattern
② Trellis pattern
③ Radial pattern
④ Rectangular pattern

Drainage Patterns (Image credits: wikipedia)

① Dendrite pattern:
It consists of a single main stream with tributaries resembling the branches of a tree. It develops when the river channel follows the slope of the terrain. e.g. Ganga

② Trellis Pattern:
When tributaries join the main stream at right angles, a pattern is called trellis. A trellis drainage pattern develops where hard and soft rocks exist parallel to each other. For example the Narmada.

③ Radial Pattern:
In this pattern, the streams flow in different directions from a central peak or dome like structure forming a radial pattern.

④ Rectangular Pattern:
It develops on a strongly joint rocky terrain. In this, the main stream and its tributaries join at right angles.


Question: Name the two Himalayan river systems.

Answer: Indus and the Ganga-Brahmaputra-Meghna system


Question: Write a short note on the Indus River system.

Answer:

The Indus River system

Indus River System (Image modified to highlight river system)
original image credits: By Kmhkmh (Own work) [CC BY 3.0 ], via Wikimedia Commons

Location:
A little over a third of the Indus basin is located in India in the states of Jammu and Kashmir, Himachal Pradesh and Punjab and the rest is in Pakistan.

Origin/ Source:
The river Indus rises in Tibet near Lake Mansarovar.

Tributaries:
The Zaskar, the Nubra, the Shyok and the Hunza join it in the Kashmir region.
The Sutlej, the Beas, the Ravi, the Chenab and Jhelum join together to enter the Indus near Mithankot in Pakistan.

Mouth
Beyond this, the Indus flows southwards eventually reaching the Arabian Sea, east of Karachi.

Gradient
The Indus plain has a very gentle slope.

Length
The total length is 2900 kilometre. It is one of the longest rivers of the world.

Feature
It forms a picturesque of a gorge in the Ladakh district of Jammu and Kashmir. The depth of Indus gorge near Bunji (J & K) is 5200 metres.


Question: Write a short note on the Ganga River system.

Answer:

The Ganga River system

Image Credits: By Pfly (Own work), CC BY-SA 3.0 via Wikimedia Commons

⑴ Source:
The headwaters of the Ganga is the Bhagirathi. It is fed by the Gangotri Glacier and joined by the Alaknanda and Devprayag in Uttaranchal.

At Haridwar, Ganga emerges from the mountains to the plains.

⑵ Himalayan tributaries:
The Jamuna, the Ghagra, the Gandak, and the Kosi.

These rivers cause widespread floods in the Northern Plains every year and cause widespread damage to life and property. But the rivers also enrich the soil for agriculture.

⑶ Peninsular tributaries:
Chambal, Betwa and the Son rise from semi-arid areas and have short courses. They do not carry much water with them.

⑷ The Ganga flows eastwards till Farakka in West Bengal, which is the northern most point of the Ganga delta.

⑸ The main stream flows southwards into Bangladesh and is joined by the Brahmaputra.

⑹ The Ganga and the Brahmaputra flow into the Bay of Bengal and form the world's largest and fastest growing Delta known as the Sundarbans delta.

⑺ The length of the Ganga is over 2500 km. Ambala is located on the water divide between the Indus and the Ganga river systems.

⑻ The gradient slope of the river is very gentle, a fall off just 1 metre for every 6 km. Therefore the river develops large meanders.


Question: Write a short note on the Brahmaputra River system.

Answer: 

The Brahmaputra River System

⑴ The Brahmaputra rises in Tibet east of Mansarovar Lake very close to the source of Indus and Sutlej.

⑵ It flows eastward parallel to the Himalayas. On reaching Namcha Barwa (7757 meters), it takes a U turn and enters India in Arunachal Pradesh through a gorge.

Here it is called the Dihang.

⑶ The Dibang, the Lohit and many other tributaries join the Dihang to form the Brahmaputra in Assam.

⑷ InTibett, the river carries a small volume of water and less tilt as it is a cold and dry area.

⑸ In India, it passes through a region of high rainfall. Here, the river carries a large volume of water and a considerable amount of silt.

⑹ The Brahmaputra has a braided channel in its entire length in Assam and forms many riverine islands.

⑺ It causes widespread devastation due to floods in Assam and Bangladesh.

⑻ Unlike the other Indian rivers of North, this river is marked by huge deposits of silt on its bed causing the river bed to rise.

⑼ The river also shifts its channel frequently.


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