Drainage
**1. Define the term drainage. Describe the four drainage patterns.
Answer: The Drainage means an area of a river system.
There are basically four types of drainage pattern .these include-
Dendritic pattern : A river with its tributaries provides a tree like pattern known as dendritic. The dendritic pattern develops where a river channel follows the slope of the terrain. For example the Ganga basin .
Trellis pattern : A river joined by its tributaries, at approximately right angle, develops a trellis pattern. Where hard and soft rock lies parallel to each other this pattern develops on that area.
Rectangular drainage pattern: These forms in the strong and jointed rocky terrain area.
Radial pattern : A radial pattern develops when streams flow in different directions from a central peak or dome like structure.
***2. State the similarities and differences between Himalayan rivers and Peninsular rivers.
There are several similarities and difference between Himalayan rivers and Peninsular rivers. These are:
Similarities
i.Both the Himalayan and peninsular river systems forms delta.
ii. Himalayan and peninsular rivers both have their large drainage pattern.
iii. The river of both the regions is joined by several tributaries which increase the volume of the water.
Differences
| Peninsular rivers | Himalayan rivers |
| These rivers are comparatively short. | These rivers are comparatively long. |
| The peninsular rivers are joined by comparatively shorter tributaries. | The Himalayan rivers are joined by large tributaries. |
| They form both deltas and estuaries. Their deltas are smaller. | They carry more silt and form the large delta. For example: Sunderban delta. |
| The peninsular rivers flow into the Bay of Bengal as well as the Arabian sea. | The Himalayan rivers in India flow into the Bay of Bengal. |
| The major peninsular rivers like the Mahanadi, the Godavari, the Krishna and the Kaveri. | The Himalayan rivers like the Ganga, the Indus and the Brahmaputra. |
**3.Which river is known as ‘Dakshin Ganga’? Explain the basic features.
The river Godavari is known as ‘Dakshin Ganga’. The basic features of this river are:
i. The Godavari is the largest peninsular river.
ii. It is the largest basin are among the peninsular rivers. It covers M.P., Odisha, Andhra Pradesh, Maharashtra etc.
iii. The Godavari is joined by a number of tributaries such as the Purna, the Wardha etc.
iv.It is known as ‘Dakshin Ganga’ because of its length and the area it covers
**4.Explain any five features of India’s longest river.
The Ganga river is the longest river of India. The basic features of Ganga river are:
i.The Ganga river basin has many tributaries joining it from both side forming a Dendritic drainage pattern .
ii. The Ganga rises in Himalayas from the Gangotri glacier. It’s main headstream ‘Bhagirathi’ is joined by Alaknanda at Devaprayag in Uttaranchal.
iii. At Haridwar, the Ganga emerges from the Himalayas flowing through Uttar Pradesh, Bihar, West Bengal, it falls in the Bay of Bengal.
***5.How does river play an important role in an agricultural economy in India?
Water from river is a basic natural resource, essential for various human activities. Therefore, the river banks attracted settlers from the ancient times.
Using rivers for irrigation, navigation, hydro– power generation is of special significance, particularly to a country like India, where agriculture is the major source of the majority of its population.
***6.What is the basic cause behind river pollution?
The growing domestic, municipal, industrial and agricultural demand for water from rivers naturally affects the quality of water and also reduces the volume of the water.
On the other hand, a heavy load of untreated sewage and industrial effluents are emptied into the river. This affects both the quality of water and the self- cleaning capacity of the river.
***7. What is watershed or a water divide?
Answer: Water divide means a mountain or it may be a highland, which divide a river basin into two part.
***8.Mention difference between east flowing and west flowing rivers of Peninsular India:
| West Flowing Rivers | East Flowing Rivers |
| Form Estuary | Form Delta |
| Flow through rift valleys.These rivers are short and swift. | Flow through shallow or natural valleys. |
| Drain in Arabian sea | Drain in Bay of Bengal |
| Example: Narmada, Tapi | Example: Mahanadi,Godavari |
8. Give any two reasons - Why are the Peninsular rivers not navigable?
Answer: Peninsular rivers are not navigable because:
• These all are seasonal rivers and generally dries up in summer.
• River beds are uneven, rocky and have sharp slopes.
9. What are the different types of lakes found in India?
Answer: The types of lakes found in India.
• Freshwater lake: Most of the freshwater lakes are in the Himalayan region. They are of
glacial origin. They formed when glaciers dug out a basin, which was later filled with
snowmelt.
• Salt water lake: India’s famous salt water Lake is the Sambhar Lake, found in Rajasthan. It
is a salt water lake and its water is used for producing salt.
10. What is ‘Drainage’?
What is a ‘Drainage Basin’?
Answer: The river system of an area called drainage.
The area drained by a single river system is called a drainage basin.
11. What is meant by a water divide? Give an example.
Answer: Any elevated area, such as a mountain or an upland, which separates two drainage basins is
called an upland. Such an upland is also known as a water divide. For example, the water
divide between the Indus and the Ganga River Systems.
12.