Drainage

Q59. How is Sunderban delta formed?

Ans. Enlarged with the waters from its right and left bank tributaries, the Ganga flows eastwards till Farakka in West Bengal. This is the northernmost point of the Ganga delta. The river bifurcates here; the Bhagirathi-Hooghly (a distributary) flows southwards through the deltaic plains to the Bay of Bengal. The mainstream, flows southwards into Bangladesh and is joined by the Brahmaputra. Further down stream, it is known as the Meghna. This mighty river, with waters from the Ganga, and the Brahmaputra, flows into the Bay of Bengal. The delta formed by these rivers is known as the Sunderban delta.

Q60. How lakes are formed?

Ans. Lakes are formed in the following ways:

                        i.        Most of the fresh water lakes are formed when glaciers dug out a basin, which was later filled with snowmelt.

                       ii.        The Wular lake in Jammu and Kashmir, in contrast, is the result of the tectonic activity. The Dal lake, Bhimtal, Nainital, Loktak and Barapani are some other important fresh water lakes.

                      iii.        Apart from natural lakes, the damming of the rivers for the generation of hydel power has also led to the formation of Lakes such as Guru Gobind Sagar (Bhakra Nangal Project).

Q61. What types of lakes are found in India? Give suitable examples.

Ans. Types of lakes found in India

                        i.        Fresh water lakes - Most of the fresh water lakes are in the Himalayan region. They are of glacial origin. The Dal lake, Bhimtal, Nainital, Loktak and Barapani are some other important fresh water lakes.

                       ii.        Salt water lake - Example, the Sambhar lake in Rajasthan, which is a salt water lake. Its water is used for producing salt.

                      iii.        Man-made lakes - Apart from natural lakes, the damming of the rivers for the generation of hydel power has also led to the formation of Lakes such as Guru Gobind Sagar (Bhakra Nangal Project).

Q62. Name the three Himalayan river systems. Write two tributaries of each.

Ans. The three Himalayan river systems are:

The Indus River System

The Ganga River System

The Brahmaputra River System

Tributaries

The Indus River System – Satluj and Beas

The Ganga River System – Yamuna and Ghaghara

The Brahmaputra River System – Lohit and Dibang

Q63. Write some features of lakes.
Or
Mention some characteristics of lakes.

Ans. Characteristics of lakes

                        i.        India has many lakes. These differ from each other in the size, and other characteristics.

                       ii.        Most lakes are permanent; some contain water only during the rainy season, like the lakes in the basins of inland drainage of semi-arid regions.

                      iii.        There are some of the lakes which are the result of the action of glaciers and ice sheets, while the others have been formed by wind, river action, and human activities.

Q64. Write a short note on the Brahmaputra River System.

Ans. The Brahmaputra rises in Tibet east of Mansarowar lake. It flows eastwards parallel to the Himalayas. On reaching the Namcha Barwa (7757 m), it takes a ‘U’ turn and enters India in Arunachal Pradesh through a gorge. Here, it is called the Dihang and it is joined by the Dibang, the Lohit, and many other tributaries to form the Brahmaputra in Assam. In Tibet the river carries a smaller volume of water and less silt as it is a cold and a dry area. In India it passes through a region of high rainfall. Here the river carries a large volume of water and considerable amount of silt. The Brahmaputra has a braided channel in its entire length in Assam and forms many riverine islands.