Unit Test (Solutions): Drainage | Social Studies (SST) Class 9 PDF Download

Time: 1 hour
M.M. 30
Attempt all questions.
Question numbers 1 to 5 carry 1 mark each.
Question numbers 6 to 8 carry 2 marks each.
Question numbers 9 to 11 carry 3 marks each.
Question numbers 12 & 13 carry 5 marks each.

Q1. Which of the following is the largest drainage basin in the world? (1 Mark) 
(a) Ganga 
(b) Amazon 
(c) Indus 
(d) Brahmaputra 

Ans: (b) Amazon
The Amazon River in South America has the largest drainage basin in the world, covering about 7 million sq km.

Q2. Which river is known as the ‘Dakshin Ganga’ ? (1 Mark) 
(a) Krishna 
(b) Godavari 
(c) Kaveri 
(d) Mahanadi 

Ans: (b) Godavari
The Godavari River is called the ‘Dakshin Ganga’ because of its large size and importance in the Peninsular region.

Q3. Which lake is the largest freshwater lake in India? (1 Mark) 
(a) Dal 
(b) Wular 
(c) Chilika 
(d) Sambhar 

Ans: (b) Wular
The Wular Lake, located in Jammu and Kashmir, is the largest freshwater lake in India and is of tectonic origin.

Q4. Which Peninsular river flows through a rift valley? (1 Mark) 
(a) Mahanadi 
(b) Narmada 
(c) Godavari 
(d) Krishna 

Ans: (b) Narmada
The Narmada River flows westwards through a rift valley formed due to faulting.

Q5. What is the name of the world’s largest riverine island formed by the Brahmaputra? (1 Mark) 
(a) Majuli 
(b) Sundarban 
(c) Loktak 
(d) Dhuadhar 

Ans: (a) Majuli
Majuli in Assam is the world’s largest riverine island, formed by the Brahmaputra River.

Q6. What is a water divide? Give an example. (2 Marks) 

Ans: A water divide is an elevated area, like a mountain or upland, that separates two drainage basins. 
Example: Ambala, separating the Indus and Ganga river systems.

Q7. Why does the Brahmaputra carry less silt in Tibet compared to India? (2 Marks) 

Ans: 

• In Tibet, the Brahmaputra (called Tsang Po) flows through a cold, dry region, resulting in less water and silt.

• In India, it flows through areas of heavy rainfall, increasing both water volume and silt load.

Q8. State two economic benefits of rivers. (2 Marks) 

Ans: 

• Provide water for irrigation, supporting agriculture.

• Generate hydroelectric power for industries and domestic use.

Q9. Describe the key features of the Indus River System. (3 Marks) 

Ans: 

• Originates near Lake Mansarovar in Tibet and flows westwards into India through Ladakh, forming a gorge.

• Tributaries in Kashmir: Zaskar, Nubra, Shyok, Hunza; further joined by Satluj, Beas, Ravi, Chenab, and Jhelum.

• Total length: 2,900 km; drains into the Arabian Sea.

• Under the Indus Water Treaty (1960), India can use only 20% of its water.

Q10. Compare the Himalayan and Peninsular rivers in terms of their flow and origin. (3 Marks) 

Ans: 

• Himalayan Rivers: Perennial, fed by rain and snowmelt; long courses; originate in the Himalayas (e.g., Indus, Ganga, Brahmaputra).

• Peninsular Rivers: Mostly seasonal, rain-fed; shorter and shallower; originate in Western Ghats or central highlands (e.g., Godavari, Krishna).

Q11. Explain the formation of the Sundarban Delta. (3 Marks) 

Ans: 

• Formed at the confluence of the Ganga and Brahmaputra in Bangladesh.

• The Ganga splits into the Bhagirathi-Hooghly and joins the Brahmaputra to form the Meghna.

• Heavy silt deposition creates the Sundarban Delta, the largest and fastest-growing delta in the world, named after the Sundari tree.

Q12. Discuss the characteristics and significance of the Godavari Basin. (5 Marks) 

Ans: 

• Largest Peninsular river; originates in Nasik district, Maharashtra; length about 1,500 km.

• Basin covers Maharashtra, Madhya Pradesh, Odisha, and Andhra Pradesh.

• Major tributaries: Purna, Wardha, Pranhita, Manjra, Wainganga, Penganga.

• Known as ‘Dakshin Ganga’ for its size and utility.

• Significance: Supports agriculture through irrigation, provides water for industries and hydropower, sustains fisheries, and boosts the economy of the region.

Q13. Analyze the role of lakes in India’s economy and tourism. (5 Marks) 

Ans: 

• Economic Role:

  • Regulate river flow, prevent floods, and supply water in dry seasons.

  • Provide water for irrigation, hydropower generation (e.g., Guru Gobind Sagar), and fishing.

• Tourism Role:

  • Attract tourists with natural beauty (e.g., Dal Lake for shikara rides).

  • Promote local economies through hospitality and recreation activities.

• Ecological Role:

  • Maintain aquatic ecosystems and moderate climate.

  • Support biodiversity and improve the environment.