DRAINAGE

Chapter 3 


EXERCISE


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

(i) In which of the following states is the Wular lake located?

(a) Rajasthan                 (c) Punjab

(b) Uttar Pradesh          (d) Jammu and Kashmir

Ans:  (d) Jammu and Kashmir

(ii) The river Narmada has its source at

(a) Satpura                   (c) Amarkantak

(b) Brahmagiri            (d) Slopes of the Western Ghats

Ans: (c) Amarkantak

(iii) Which one of the following lakes is a salt water lake?

(a) Sambhar                 (c) Wular

(b) Dal                          (d) Gobind Sagar

Ans: (a) Sambhar.

(iv) Which one of the following is the longest river of the Peninsular India?

(a) Narmada                   (c) Godavari

(b) Krishna                     (d) Mahanadi

Ans:   (c) Godavari

(v) Which one amongst the following rivers flows through a rift valley?

(a) Mahanadi                 (c) Krishna

(b) Tungabhadra           (d) Tapi

Ans:  (d) Tapi   

2. Answer the following questions briefly.

(i) What is meant by a water divide? Give an example.

Ans: A water divide, also known as a drainage divide, ridgeline, watershed, water parting, or height of land, is a topographical feature that separates neighboring drainage basins. On rugged land, the divide lies along topographical ridges, and may be in the form of a single range of hills or mountains, known as a dividing range. On flat terrain, especially where the ground is marshy, the divide may be difficult to discern.

Here are some examples of water divides:

*The Continental Divide in North America separates the watersheds of the Pacific Ocean from those of the Atlantic Ocean and the Gulf of Mexico.

*The Great Dividing Range in Australia separates the watersheds of the Pacific Ocean from those of the Indian Ocean.

*The Alps Mountains separate the watersheds of the Danube River from those of the Po River.

*The Himalayas Mountains separate the watersheds of the Indus River, the Ganges River, and the Brahmaputra River.

*The Andes Mountains separate the watersheds of the Amazon River from those of the Paraná River.

(ii) Which is the largest river basin in India?

Ans: The largest river basin in India is the Ganga basin, also known as the Ganges basin. It covers an area of approximately 1,080,000 square kilometers (417,000 square miles), making it the fifth largest river basin in the world by discharge and the tenth largest by area.

(iii) Where do the rivers Indus and Ganga have their origin?

Ans: The rivers Indus and Ganga both originate in the Himalayas, but in different parts of the mountain range. The Indus River originates in Tibet, near Mount Kailash, and flows westward through the mountains into Pakistan. The Ganga River originates in the Gangotri Glacier in the Himalayas, and flows eastward through India into the Bay of Bengal. Here is a more detailed description of the origins of each river:

*Indus River: The Indus River originates near Lake Manasarovar in Tibet, at an elevation of about 5,150 meters (16,900 feet). It flows westward through the Tibetan Plateau, then turns southward into Kashmir. From there, it flows through Pakistan, eventually emptying into the Arabian Sea near Karachi. The Indus River is the longest river in Pakistan, and the seventh longest river in Asia. It is also the most important river in Pakistan, providing irrigation for agriculture and supporting a large population.


*Ganga River: The Ganga River originates in the Gangotri Glacier in the Himalayas, at an elevation of about 7,000 meters (23,000 feet). It flows eastward through the Himalayas, then turns southward into the plains of India. From there, it flows through the states of Uttar Pradesh, Bihar, and West Bengal, eventually emptying into the Bay of Bengal near Kolkata. The Ganga River is the longest river in India, and the third longest river in Asia. It is also the most important river in India, providing irrigation for agriculture and supporting a large population.

Here is a table summarizing the origins of the Indus and Ganga Rivers:




(iv) Name the two headstreams of the Ganga. Where do they meet to form the Ganga?

Ans: The two headstreams of the Ganga are the Bhagirathi and the Alaknanda. They meet to form the Ganga at Devprayag, a town in the state of Uttarakhand, India. The Bhagirathi originates in the Gangotri Glacier, and the Alaknanda originates in the Satopanth Glacier. From Devprayag, the Ganga flows eastward through the plains of India, eventually emptying into the Bay of Bengal near Kolkata.

(v) Why does the Brahmaputra in its Tibetan part have less silt, despite a longer course?

Ans:  The Brahmaputra River carries less silt in its Tibetan part, despite its longer course, due to several factors:

1. Climate: The Tibetan Plateau is a cold and dry region, with low rainfall and limited vegetation cover. This results in less erosion of the land and less sediment being carried by the river.

2. Gradient: The Brahmaputra River flows through a steeper gradient in its Tibetan part, which causes the water to flow faster and with more turbulence. This turbulence helps to suspend sediment in the water, but it also prevents much of the sediment from settling on the riverbed.

3. Glacial Meltwater: A significant portion of the Brahmaputra River's flow in its Tibetan part comes from glacial meltwater. Glacial meltwater is typically very clear and contains little sediment.

4. Lack of Tributaries: The Brahmaputra River has few tributaries in its Tibetan part. Tributaries are smaller rivers or streams that join a larger river, and they can contribute significant amounts of sediment to the main river.

    In contrast, when the Brahmaputra River enters India, it flows through a warmer, wetter region with more vegetation cover and a more gentle gradient. This leads to increased erosion of the land, more sediment being carried by the river, and more sediment settling on the riverbed. As a result, the Brahmaputra River carries much more silt in its Indian part than in its Tibetan part.

(vi) Which two Peninsular rivers flow through trough?

Ans: The two peninsular rivers that flow through a trough are the Narmada and Tapi rivers. They flow through a rift valley that is known as the Narmada-Tapi rift valley. The rift valley is a long, narrow depression in the Earth's crust that was formed by the pulling apart of two tectonic plates. The Narmada and Tapi rivers both originate in the Satpura Mountains and flow westward through the rift valley before emptying into the Gulf of Khambhat in Gujarat.

(vii) State some economic benefits of rivers and lakes.

Ans: Rivers and lakes provide a wide range of economic benefits to society. These benefits include:

1. Irrigation: Rivers and lakes are essential sources of water for irrigation, which is vital for agriculture. Irrigation allows farmers to grow crops in areas that would otherwise be too dry for agriculture, and it helps to increase crop yields in areas that have adequate rainfall.

2. Hydropower: Rivers and lakes can be harnessed to generate hydropower, a clean and renewable source of energy. Hydropower plants use the energy of moving water to generate electricity, which can be used to power homes, businesses, and industries.

3. Navigation: Rivers and lakes provide important waterways for transportation. Boats and ships can transport goods and people between different parts of a country or region, which can help to reduce transportation costs and promote trade.

4. Tourism: Rivers and lakes are popular tourist destinations. People enjoy fishing, boating, swimming, and other recreational activities on and around rivers and lakes. Tourism can generate significant economic benefits for local communities.

5. Water supply: Rivers and lakes are important sources of water for drinking, sanitation, and industrial use. Water treatment plants draw water from rivers and lakes and purify it for use in homes, businesses, and industries.

6. Flood control: Rivers and lakes can be managed to reduce the risk of flooding. Dams and reservoirs can store excess water during floods, and floodplains can be used to provide space for floodwaters to spread out.

7. Ecosystem services: Rivers and lakes provide a variety of ecosystem services, such as water filtration, nutrient cycling, and habitat for fish and other wildlife. These ecosystem services are essential for the health and well-being of human societies.

    In addition to these direct economic benefits, rivers and lakes also provide indirect economic benefits by supporting a wide range of industries, including agriculture, tourism, and manufacturing. They also contribute to the overall quality of life by providing recreational opportunities and enhancing the beauty of the natural landscape.

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

(a) Wular                             (b) Dal

(c) Nainital                          (d) Bhimtal

(e) Gobind Sagar                 (f) Loktak

(g) Barapani                        (h) Chilika

(i) Sambhar                         (j) Rana Pratap Sagar

(k) Nizam Sagar                  (l) Pulicat

(m) Nagarjuna Sagar         (n) Hirakund

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

Ans: 

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

Ans: Here is a more detailed comparison of the east-flowing and west-flowing rivers of the Peninsular plateau:

Origin: The east-flowing rivers of the Peninsular plateau originate in the Western Ghats, a mountain range that runs along the western coast of India. The west-flowing rivers of the Peninsular plateau originate in the central highlands of India.

Flow direction: The east-flowing rivers flow eastward and eventually empty into the Bay of Bengal. The west-flowing rivers flow westward and eventually empty into the Arabian Sea.

Estuary or delta: The east-flowing rivers typically form deltas at their mouths. A delta is a triangular-shaped deposit of sediment that is formed where a river slows down and spreads out as it enters a larger body of water, such as an ocean or a sea. The west-flowing rivers typically form estuaries at their mouths. An estuary is a partially enclosed coastal body of fresh water that is open to the ocean.

Water volume: The east-flowing rivers carry a larger volume of water than the west-flowing rivers. This is because the east-flowing rivers have a larger catchment area and receive more rainfall.

Examples: Some of the major east-flowing rivers of the Peninsular plateau include the Mahanadi, Godavari, Krishna, and Kaveri rivers. Some of the major west-flowing rivers of the Peninsular plateau include the Narmada and Tapi rivers.

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

Ans: Rivers play a crucial role in the economic development of a country by providing a multitude of resources and supporting various industries. Here's a detailed explanation of the economic significance of rivers:

1. Irrigation: Rivers serve as the primary source of water for agriculture, enabling farmers to cultivate crops in areas with insufficient rainfall. Irrigation ensures consistent crop production, enhances agricultural productivity, and contributes to food security.

2. Hydropower Generation: Rivers are a valuable source of renewable energy through hydropower plants. These plants harness the energy of moving water to generate electricity, which powers homes, businesses, and industries. Hydropower is a clean and sustainable energy source, reducing reliance on fossil fuels.

3. Navigation and Transportation: Rivers provide crucial waterways for transportation, facilitating the movement of goods and people. Ships and boats can transport cargo efficiently between different regions, reducing transportation costs and promoting trade. Rivers also serve as tourist attractions, generating revenue through recreational activities like boating, fishing, and sightseeing.

4. Industrial Water Supply: Rivers provide a continuous supply of water for various industrial processes, including manufacturing, cooling systems, and waste disposal. Industrial water usage is essential for economic growth and development.

5. Domestic Water Supply: Rivers are a vital source of freshwater for drinking, sanitation, and household purposes. Water treatment plants draw water from rivers, purify it, and supply it to homes and communities.

6. Flood Control and Water Management: Rivers can be managed to minimize the risk of floods and droughts. Dams and reservoirs can store excess water during floods, and floodplains can be used to provide space for floodwaters to spread out. Rivers can also be regulated to ensure a steady water supply throughout the year.

7. Ecosystem Services and Biodiversity: Rivers support a diverse range of aquatic ecosystems, providing habitats for fish and other wildlife. These ecosystems play a crucial role in maintaining water quality, nutrient cycling, and overall environmental health.

8. Cultural and Recreational Significance: Rivers hold cultural and recreational significance, providing spaces for leisure activities, religious ceremonies, and traditional practices. They also enhance the aesthetic beauty of landscapes and contribute to the overall quality of life.

    In conclusion, rivers are indispensable resources that contribute significantly to a country's economy by supporting agriculture, generating hydropower, facilitating transportation, providing water for industries and households, and maintaining ecosystems. Their management and conservation are essential for sustainable economic development and environmental well-being.

Map Skills

(i) On an outline map of India mark and label the following rivers: Ganga,

Satluj, Damodar, Krishna, Narmada, Tapi, Mahanadi, and Brahmaputra.

(ii) On an outline map of India mark and label the following lakes: Chilika, Sambhar, Wular, Pulicat, Kolleru.


Questions and Answer Type By : Himashree Bora.

Post ID: DABP002251