Short & Long Question Answer: Drainage

Q1: Why are the Peninsular rivers seasonal in nature?
Ans: The Peninsular rivers are seasonal because their flow depends mainly on monsoon rainfall rather than on melted snow. They rise on the old, weathered Peninsular plateau and have shorter, shallower courses with limited groundwater recharge. During the rainy season these rivers carry a lot of water, but in the dry season their flow reduces greatly, and some may even dry up in stretches. These factors make Peninsular rivers largely dependent on seasonal rains.

Q2: Give the features of the Himalayan rivers.
Ans: Most Himalayan rivers are perennial, carrying water throughout the year because they are fed by both glacial melt and the monsoon rainfall. They have long courses from the mountains to the sea and perform strong erosional activity in their upper reaches, carrying large loads of silt and sand. In their middle and lower courses they show depositional features such as meanders and ox-bow lakes and build extensive floodplains and well-developed deltas near their mouths.

Q3: Give some of the similarities between the Himalayan rivers and Peninsular rivers.
Ans: Although Himalayan and Peninsular rivers differ in many ways, they share some features:

• Both systems have large drainage basins that collect water from wide areas.
• Many rivers in both systems form deltas or depositional features at their mouths where they meet the sea.
• Rivers in both regions receive water from several tributaries, which help increase the volume of the main river and bring silt.

Q4: Describe the following drainage patterns of streams:
(i) Radial
(ii) Dendrite
(iii) Trellis
(iv) Rectangular
Ans:

• Radial: Streams flow outward in different directions from a central peak or dome, producing a pattern like the spokes of a wheel.
• Dendritic: The drainage resembles the branches of a tree. This pattern develops where the river channel follows the general slope of a uniform surface or rock type.
• Trellis: Occurs where alternate bands of hard and soft rocks lie parallel. Main streams run along the valleys while tributaries join at near right angles, producing a garden-trellis-like pattern.
• Rectangular: Develops on strongly jointed or faulted rocks, where channels follow the joints and meet at sharp angles, creating a rectangular pattern.

Q5: Which three river systems form the Himalayan river system? Describe briefly any one of them.
Ans: The three river systems that form the Himalayan river system are:

• The Indus river system
• The Ganga river system
• The Brahmaputra river system
• The Brahmaputra rises in Tibet, east of Mansarovar Lake, close to the sources of the Indus and the Satluj. Most of its course lies outside India; it flows eastwards parallel to the Himalayas and enters India in Arunachal Pradesh through a gorge. In India it is joined by tributaries such as the Dibang and the Lohit, and in Assam it carries a large volume of water and silt. Throughout its course in Assam it often has a braided channel and forms many riverine islands. During the rainy season it frequently overflows its banks, causing widespread flooding in Assam and downstream in Bangladesh.

Q6: Where does river Brahmaputra rise? Where does it enter into India? Name two of its tributaries.
Ans: River Brahmaputra rises in Tibet, east of Mansarovar Lake, close to the sources of the Indus and the Satluj. It enters India in Arunachal Pradesh through a gorge. Two of its important tributaries are the Dibang and the Lohit.

Q7: What is the difference between tributary and distributary? Write any three points of distinction.
Ans:

• A tributary is a stream or river that flows into a larger river, thereby increasing the volume of the main river.
• A distributary is a branch that flows away from the main river, usually in the lower course or delta, and thus reduces the volume of the main channel at that point.
• Example: The Yamuna is a tributary of the Ganga, whereas the Hooghly is a distributary of the Ganga.

Q8: Describe three important characteristics of Sundarbans Delta.
Ans:

• It is the world's largest delta, formed mainly by the deposition of sediments brought down by the Ganga-Brahmaputra river system.
• It is a vast mangrove forest and is the natural habitat of the Royal Bengal tiger and many other species.
• The name Sundarbans comes from the Sundari tree, which grows well in the marshy, tidal land of the delta.

Q9: Describe the three main features of the Narmada basin.
Ans:

• The Narmada flows westward through a rift valley formed by faulting, creating scenic gorges and valleys.
• Most of its tributaries are short and many join the main stream at or near right angles, reflecting the structural control on drainage.
• The basin extends over parts of Madhya Pradesh and Gujarat, bounded by the Vindhyas to the north, Maikala range to the east, the Satpuras to the south and the Arabian Sea to the west.

Q10: Define drainage basin and describe two patterns of drainage in India.
Ans:

• Drainage basin: The area drained by a single river system is called a drainage basin.
• Radial: Streams flow in different directions from a central high point such as a dome or peak, producing a pattern like spokes on a wheel.
• Dendritic: This tree-like pattern forms where the river follows the general slope of the land and rock type is relatively uniform; tributaries join the main stream at acute angles.

Q11: Where does the river Narmada originate? Name any two picturesque locations formed by it.
Ans: The Narmada rises in the Amarkantak hills in Madhya Pradesh. Two notable picturesque locations formed by it are the Marble Rocks near Jabalpur, where the river flows through a deep gorge, and the Dhuadhar Falls, where the river plunges over steep rocks to form a dramatic waterfall.

Q12: Where does the river Indus rise from? What is its length? Write any two tributaries of river Indus.
Ans: The river Indus rises near Mansarovar Lake on the Tibetan plateau, on the northern slopes of the Kailash range. Flowing westward, it enters India in the Ladakh district of Jammu and Kashmir. Its total length is about 2,900 km. Two of its tributaries are the Zanskar and the Nubra.

Q13: Where does the river Tapi originate? Write its main features.
Ans:

• The Tapi rises in the Satpura ranges in Betul district of Madhya Pradesh.
• It flows westwards in a rift valley roughly parallel to the Narmada but is considerably shorter in length. Its basin covers parts of Madhya Pradesh, Maharashtra and Gujarat.
• The basin has two main physical regions: hilly, well-forested tracts in the uplands and broad fertile plains suitable for agriculture in the lower reaches.

Q14: Describe important features of the Mahanadi basin. Give three factual pieces of information about the Mahanadi basin.
Ans: The Mahanadi rises in the highlands of Chhattisgarh and flows eastwards through Odisha to reach the Bay of Bengal. Its total length is about 860 km. The drainage basin of the Mahanadi is shared by Maharashtra, Chhattisgarh, Jharkhand and Odisha. The river forms a fertile plain and a delta near its mouth that supports agriculture in the region.

Q15: Where does the river Kaveri originate? What is its total length? Name its main tributaries.
Ans: The Kaveri rises in the Brahmagiri range of the Western Ghats. It flows southeast and reaches the Bay of Bengal south of Cuddalore in Tamil Nadu. Its total length is about 760 km. Major tributaries include the Amravati, Bhavani, Hemavati and Kabini. The Kaveri basin drains parts of Karnataka, Kerala and Tamil Nadu.

Q16: Describe important features of the Krishna basin.
Ans: The Krishna is an important Peninsular river. It rises from a spring near Mahabaleshwar and flows for about 1,400 km to drain into the Bay of Bengal. Its tributaries include the Tungabhadra, Koyana, Ghataprabha, Musi and Bhima. The Krishna basin covers parts of Maharashtra, Karnataka and Andhra Pradesh and supports significant irrigation and agriculture.

Q17: Which two peninsular rivers form estuaries? Name the states in which these rivers drain the water.
Ans: The two peninsular rivers that form estuaries are the Narmada and the Tapi. The Narmada drains through the states of Madhya Pradesh and Gujarat. The Tapi drains parts of Madhya Pradesh, Maharashtra and Gujarat.

Q18: Why do the Himalayan rivers get flooded every year? Mention the main advantages of these rivers.
Ans: The Himalayan rivers are perennial, fed by glacial melt and by heavy monsoon rainfall. During the rainy season, intense precipitation and increased melting of snow and ice cause these rivers to swell and often overflow their banks, resulting in annual floods. Main advantages of Himalayan rivers include:

• They carry large amounts of silt, enriching the soil of the northern plains and making the region extremely fertile for agriculture.
• They provide excellent potential for hydroelectric power, and their waters are used extensively for irrigation and navigation in suitable stretches.

Q19: Why are the peninsular rivers not navigable?
Ans: The peninsular rivers are largely seasonal and their flow depends on the monsoon. In the dry season many of these rivers have very low discharge or may dry up in stretches. Their channels are often shallow, rocky and broken by rapids and waterfalls, which interrupt continuous navigation. These factors make regular navigation difficult on most Peninsular rivers.

Q20: Give a brief description of freshwater lakes found in India.
Ans: Many freshwater lakes in India are located in the Himalayan region and are of glacial origin, formed where glaciers dug basins later filled by meltwater. The Wular lake in Jammu and Kashmir is the largest freshwater lake in India and is partly tectonic in origin. Other important freshwater lakes include the Dal lake, Bhimtal, Nainital, Loktak and Barapani.

Q21: Describe how the lakes found in India differ from each other in size, and other characteristics.
Ans:
Lakes in India vary widely in size and origin. Key differences include:

• Some lakes are permanent, while others are seasonal, holding water mainly during the rainy season, especially in semi-arid inland drainage basins.
• Origins differ: some lakes are of glacial origin, others are formed by river action, wind action, tectonic movements or are created by human activity (reservoirs).
• Meandering rivers may form ox-bow lakes where cut-offs of bends become separate waterbodies in floodplains.

Q22: Which is the largest peninsular river? Describe some of its important features.
Ans:
The Godavari is the largest peninsular river. Some important features are:

• It rises in the Western Ghats in the Nasik district of Maharashtra and has a length of about 1,500 km.
• It drains into the Bay of Bengal and has the largest drainage basin among the peninsular rivers.
• The basin covers parts of Maharashtra, Madhya Pradesh, Chhattisgarh, Odisha and Andhra Pradesh.
• It is joined by many tributaries such as the Purna, Wardha, Pranhita, Manjra, Wainganga and Penganga, several of which are large.
• Because it drains much of peninsular India and supports large agricultural tracts, the Godavari is often called the 'Dakshin Ganga' (the Ganga of the South).

Q23: Describe the important characteristics of the Brahmaputra river system.
Ans:
The Brahmaputra rises in Tibet, east of Mansarovar Lake, near the sources of the Indus and the Satluj. It flows eastwards parallel to the Himalayas before entering India in Arunachal Pradesh through a gorge. In India it is joined by tributaries such as the Dibang and the Lohit to form a mighty river in Assam. In the Indian part the river passes through a region of high rainfall and thus carries a large volume of water and silt. The Brahmaputra often has a braided channel in Assam and forms many riverine islands (chars). Every year during the rainy season it frequently overflows its banks, causing widespread flooding in Assam and Bangladesh.

Q24: Give the main features of the Ganga river system.
Ans:
The Ganga river system consists of the main river and many tributaries such as the Yamuna, Ghaghara, Gandak and Kosi. Main features are:

• It drains a very large area including the middle Himalayas in the north, the northern part of the peninsular plateau in the south and the extensive Ganga plain between them; the Ganga plain is one of the most fertile plains in the world.
• The Ganga originates as Bhagirathi from the Gangotri glacier in Uttarkashi district (Uttarakhand) at about 7,010 m; the Alaknanda joins it at Devprayag.
• After leaving the hills at Haridwar, it flows across the plains to Allahabad (Prayagraj), where it is joined by the Yamuna. Enlarged by many tributaries, the Ganga continues eastwards towards Farakka in West Bengal and then flows into Bangladesh, where it is joined by the Brahmaputra and ultimately reaches the Bay of Bengal as a vast river system.
• The total length of the Ganga is over 2,500 km, and its basin is one of the most densely populated regions in the world, supporting more than 400 million people.

Q25: Which are the major Himalayan rivers? Give a brief description of the Indus river system.
Ans:

• The major Himalayan rivers are the Indus, the Ganga and the Brahmaputra.
• The Indus originates near Mansarovar Lake on the Tibetan plateau and flows westward. It enters India in the Ladakh region of Jammu and Kashmir, and thereafter flows into Pakistan through regions such as Gilgit and Baltistan, running southward across Pakistan to join the Arabian Sea east of Karachi.
• Together with its major tributaries - the Satluj, Beas, Ravi, Chenab and Jhelum - the Indus forms a large river system that is vital for irrigation and development in the region. The total length of the Indus is about 2,900 km, and a significant portion of its basin lies in Pakistan while part of it extends into Indian states of Jammu and Kashmir, Himachal Pradesh and Punjab.