CBSE Class 11 Geography NCERT Solutions: Chapter 3 - Drainage System

Solution: The correct option is (d) The Damodar. The Damodar River has historically been referred to as the 'Sorrow of Bengal' because its erratic flow and frequent, devastating floods caused significant damage and hardship to the region for many years.

Solution: The correct option is (c) The Ganga. The Ganga River system possesses the largest river basin in India, covering a vast geographical area and supporting a significant portion of the country's population.

Solution: The correct option is (c) The Indus. The term 'Panchnad' refers to the confluence of the five major rivers of the Punjab region (Jhelum, Chenab, Ravi, Beas, and Sutlej) before they merge with the Indus River. The Indus itself is a separate and larger river system.

Solution: The correct option is (b) The Narmada. The Narmada River is a prominent example of a river that flows through a rift valley, a geological feature formed by tectonic activity where the land between two parallel faults subsides.

Solution: The correct option is (d) Deva Prayag. Deva Prayag is the sacred location in Uttarakhand where the Alaknanda River and the Bhagirathi River meet. This confluence marks the formation of the main Ganges River.

Solution:

The primary difference between a river basin and a watershed lies in their scale and the rivers they encompass:

• River Basin: This term is used to describe the entire area drained by a large river and its tributaries. It includes all the land from which water flows into the main river. River basins are typically extensive geographical regions.
• Watershed: A watershed refers to a smaller area of land where all the surface water converges to a single point, such as a larger river, lake, or ocean. It is often used for smaller streams, rivulets, or rills. Watersheds are smaller in scale compared to river basins.

In essence, a river basin is a macro-level concept covering a large river system, while a watershed is a micro-level concept often applied to smaller drainage areas.

Solution:

Dendritic and Trellis are two distinct types of drainage patterns observed in river systems, differing in their formation and appearance:

• Dendritic Drainage Pattern: This pattern develops when the river's tributaries spread out and join the main river in a manner that resembles the branches of a tree. It typically forms in areas where the underlying rock structure is uniform and offers little resistance to erosion. The drainage pattern of the Great Plains of North India is a classic example of a dendritic pattern.
• Trellis Drainage Pattern: A trellis drainage pattern is formed when the river and its tributaries are influenced by structural controls, such as folded mountains, where the tributaries flow roughly parallel to each other and join the main river at nearly right angles. This creates a net-like or lattice-like structure. Examples can be found in the older folded mountains of regions like Singhbhum and in the upper reaches of the Himalayan rivers.