DRAINAGE SYSTEMS TEXT BOOK QUESTIONS AND ANSWERS - #CLASS9#GEOGRAPHY

 

DRAINAGE SYSTEMS TEXT BOOK QUESTIONS AND ANSWERS - #CLASS9#GEOGRAPHY

 (i) What is meant by a water divide? Give an example. An elevated area, such as a mountain or an upland, that separates two drainage basins is known as a water divide. An example is Ambala, which is located on the water divide between the Indus and the Ganga river systems.

(ii) Which is the largest river basin in India? The largest river basin in India is that of the Ganga river system. Although the document does not explicitly state the largest river basin in India, it prompts the reader to find out which river has the largest basin in India , and later discusses the Ganga River System and its extensive network of tributaries. The world's largest drainage basin is the Amazon river.

(iii) Where do the rivers Indus and Ganga have their origin? The river Indus rises in Tibet, near Lake Mansarowar. The headwaters of the Ganga, called the 'Bhagirathi', are fed by the Gangotri Glacier.

(iv) Name the two headstreams of the Ganga. Where do they meet to form the Ganga? The two headstreams of the Ganga are the Bhagirathi and the Alaknanda. They meet at Devaprayag in Uttarakhand to form the Ganga.

(v) Why does the Brahmaputra in its Tibetan part have less silt, despite a longer course? In Tibet, the Brahmaputra river carries a smaller volume of water and less silt because it is a cold and dry area. In contrast, in India, it passes through a region of high rainfall and carries a large volume of water and considerable silt.

(vi) Which two Peninsular rivers flow through a trough (rift valley)? The Narmada and the Tapi are the two Peninsular rivers that flow through a rift valley.

(vii) State some economic benefits of rivers and lakes. Rivers and lakes offer several economic benefits:

• Irrigation: Water from rivers is crucial for irrigation, especially in countries like India where agriculture is a primary source of livelihood.
• Navigation: Rivers are used for transportation and navigation.
• Hydel Power Generation: Both rivers and lakes can be used for generating hydroelectric power.
• Moderating Climate: Lakes help moderate the climate of their surroundings.
• Tourism and Recreation: Lakes enhance natural beauty, develop tourism, and provide recreation, attracting thousands of tourists.
• Maintaining Water Flow: Lakes help regulate the flow of rivers, preventing flooding during heavy rains and maintaining an even flow of water during the dry season.
• Source of Natural Resource: Water from rivers is a basic natural resource essential for various human activities.

3. Below are given names of a few lakes of India. Group them under two categories – natural and created by human beings.

Natural Lakes:

• Wular
• Dal
• Nainital
• Bhimtal
• Loktak
• Barapani
• Chilika
• Sambhar
• Pulicat
• Kolleru

Created by Human Beings (Artificial Lakes):

• Gobind Sagar (Bhakra Nangal Project)
• Rana Pratap Sagar (Implied by context of other reservoirs on map)
• Nizam Sagar (Implied by context of other reservoirs on map)
• Nagarjuna Sagar (Implied by context of other reservoirs on map)
• Hirakud (While not explicitly mentioned as man-made in the text, it is a well-known reservoir/dam in India, often associated with human intervention for water management).

4. Discuss the significant difference between the Himalayan and the Peninsular rivers.

Feature	Himalayan Rivers	Peninsular Rivers
Origin	Originate from the Himalayas	Many originate in the Western Ghats or central highlands
Perennial/Seasonal	Perennial (water throughout the year)	Seasonal (flow dependent on rainfall)
Water Source	Rain and melted snow from lofty mountains	Primarily rainfall
Course Length	Long courses from source to sea	Shorter and shallower courses
Erosional/Depositional Activity	Intensive erosional activity in upper courses, form meanders, ox-bow lakes, and deltas in middle/lower courses	Less intensive erosional activity; some form deltas or estuaries
Silt Load	Carry huge loads of silt and sand	Generally carry less silt due to shorter courses
Examples	Indus, Ganga, Brahmaputra	Mahanadi, Godavari, Krishna, Kaveri, Narmada, Tapi
Gorges	Cut through mountains making gorges	Narmada flows through a deep gorge

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5. Compare the east flowing and the west flowing rivers of the Peninsular plateau.

Feature	East Flowing Peninsular Rivers	West Flowing Peninsular Rivers
Direction of Flow	Flow eastwards	Flow westwards
Drainage Basin	Drain into the Bay of Bengal	Drain into the Arabian Sea
Course Length	Generally longer	Generally shorter, especially coastal rivers
Depositional Features	Make deltas at their mouths	Make estuaries (Narmada and Tapi)
Examples	Mahanadi, Godavari, Krishna, Kaveri	Narmada, Tapi, Sabarmati, Mahi, Bharathpuzha, Periyar
Origin	Most originate in the Western Ghats or central highlands	Some originate in the central highlands , or Satpura ranges , or Amarkantak hills
Rift Valley	Do not flow through rift valleys (generally)	Narmada and Tapi flow through rift valleys

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6. Why are rivers important for the country’s economy?

Rivers are fundamentally important for a country's economy due to several reasons:

• Basic Natural Resource: Water from rivers is a basic natural resource essential for various human activities.
• Agriculture: Rivers provide water for irrigation, which is of special significance in countries like India where agriculture is the major source of livelihood for the majority of the population.
• Settlements and Urbanization: Riverbanks have attracted settlers since ancient times, and these settlements have evolved into big cities, highlighting their role in the development of human civilization and urban centers.
• Navigation: Rivers serve as important routes for transportation and navigation, facilitating trade and movement of goods.
• Hydro-power Generation: Rivers are a source for generating hydroelectric power, which is vital for energy needs and industrial development.
• Livelihood: Beyond agriculture, rivers support various livelihoods such as fishing and provide water for industries.