NCERT Solutions for Class 11 Geography Chapter 3 - Drainage System

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    76. Choose the right answer from the four alternatives given below.

    (i) Which of the following rivers was known as the ‘Sorrow of Bengal’?

    (a) The Gandak

    (b) The Son

    (c) The Kosi

    (d) The Damodar

    Ans. (d) The Damodar

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

    (a) The Indus

    (b) The Brahmaputra

    (c) The Ganga

    (d) The Krishna

    Ans. (c) The Ganga

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

    (a) The Ravi

    (b) The Chenab

    (c) The Indus

    (d) The Jhelum

    Ans. (c) The Indus

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

    (a) The Son

    (b) The Narmada

    (c) The Yamuna

    (d) The Luni

    Ans. (b) The Narmada

    (v) Which 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

    Ans. (d) Deva Prayag

    77. State the differences between the following.

    (i) River Basin and Watershed


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

    (ii) Dendritic and Trellis drainage pattern


    Dendritic Drainage Pattern Trellis Drainage Pattern
    Dendritic drainage system is a 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 the Northern plain is an example of such a pattern. This pattern is found in the 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, 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’.
    Example: The rivers originating from the Amarkantak range. Example: Sambhar Lake of Rajasthan.

    (iv) Delta and Estuary


    Delta Estuary
    Delta is a triangular land mass formed by depositional alluvium at the mouth of river. Estuary is the sunken mouth of the river where the rivers meets the sea forming the tunnel shaped zone where saline and fresh water mix.
    They develop close to the river mouth on the tideless sea shore, where silt from the rivers is deposited. At the river mouth, where no deposition occurs, they are the result of intense currents and high tides.
    They are rich agricultural grounds. They are rich fishing grounds and are suitable for inland transportation.
    Rivers like Krishna, Kaveri, Mahanadi, Godavari form deltas. Narmada and Tapi form estuaries.

    78. Answer the following questions in about 30 words.

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

    Ans. Indian rivers are divided into two categories: Perennial rivers, where water is present yearround, and Peninsular rivers, where water is present only during rainy seasons. India’s rivers carry a lot of water each year. But when looking at time and location, its distribution is not equal. During the rainy season, the majority
    of the water is lost in floods. It also results in human and material loss. Additionally, it harms agriculture. There is a drought scenario in other regions.

    Therefore, the issues of floods and drought will be resolved if rivers are connected to one another by canals. Millions of rupees will be saved, and the drinking water issue will also be resolved. Additionally, it will result in higher production. The economic situation of farmers will improve.

    (ii) Write three characterstics of the Peninsular river.

    Ans. Three characteristics of peninsular rivers are as follows:

    (a) These rivers have their source in the central highlands and peninsular plateau. These depend on monsoon rainfall. Thus, they are seasonal.

    (b) They reflect a form of a drainage pattern that is superimposed, and when they are regenerated, they produce trellis, radial, and rectangular patterns.

    (c) These rivers have well-aligned valleys and a set route. Their basin’s catchment area is comparatively smaller. Old rivers having a sloped profile, these rivers have nearly reached their base levels.

    79. 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?

    Ans. Important characteristics of north Indian rivers are as follows:

    (a) Origin: They emerge from the glaciercovered Himalayan mountains.

    (b) These are perpetual because they receive water from rains and glaciers.

    (c) Drainage pattern: These are prerequisites, which, in turn, cause a dendritic pattern in plains.

    (d) River characteristics include a lengthy course, headward erosion from the mountains it flows through, river capture, and meandering on the plains.

    (e) Very large basins are included in its catchment regions.

    (f) These rivers are young and vibrant in age. In the valleys, these are active and getting deeper.

    These are different from peninsular rivers because peninsular rivers have the following features:

    (a) The peninsular plateau and central highlands are the regions of their origin.

    (b) They are seasonal in nature since they are reliant on monsoon rainfall.

    (c) Drainage style: Superimposed, revitalised, producing trellis, radial, and rectangular patterns.

    (d) Smaller, fixed-course rivers with wellaligned valleys.

    (e) Basin’s catchment area is rather limited. 

    (f) Older rivers have a sloped profile and they have nearly reached their base levels.

    (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.

    Ans. We will come across the rivers Tons, Gomti, Saryu, Ramganga, Sharda, Gandak, Old Gandak, Kamla, Bagmati, Kosi, and Ganga as we travel from Haridwar to Siliguri through the foothills of the Himalayas.

    In terms of its basin and cultural significance, the Ganga is the most significant river in India. In the Uttarkashi district of Uttarakhand, at the height of 3,900 m above sea level, it rises in the Gangotri glacier next to Gaumukh. In this area, it is referred to as the Bhagirathi. At Devaprayag, the Bhagirathi meets the Alaknanda; hereafter, it is known as the Ganga. The Ganga enters the plains at Haridwar. From here, it flows first to the south, then to the south¬east and east before splitting into two distributaries, namely the Bhagirathi and the Hugli. In India alone, the Ganga basin spans an area of around 8.6 lakh sq. km. The Ganga river system, which includes several perennial and non-perennial rivers, is the biggest in India.

    Yamuna joins the Ganga at Prayag (Allahabad). It is joined by the Chambal, the Sind, the Betwa and the Ken on its right bank, which originates from the Peninsular plateau, while the Hindan, the Rind, the Sengar, the Varuna, etc. join it on its left bank.

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