Revision notes class 9th S.st (Geography) Ch:3 Drainage
Drainage
Water Divide
A Gorge
Major Rivers and Lakes
Confluence of Bhagirathi and Alaknanda at Devaprayag
Loktak Lake
Chapter 3
✳️Introduction
💢The area drained by a single river system is called a drainage basin.
💢A closer observation on a map will indicate that any elevated area, such as a mountain or an upland, separates two drainage basins. Such as upland is known as a water divide.
✳️Drainage Systems In India
💢The drainage systems of India are mainly controlled by the broad relief features of the subcontinent.
✴️The Indian rivers are divided into two major groups:
✳️:The Himalayan rivers
✳️:The Peninsular rivers
💢The two major physiographic regions of India, the Himalayan and the Peninsular rivers are different from each other in many ways.
💢Most of the Himalayan rivers are perennial.
💢The two major Himalayan rivers, the Indus and the Brahmaputra originate from the north of the mountain ranges. They have cut through the mountains making gorges.
💢The Peninsular rivers have shorter and shallower courses as compared to their Himalayan counterparts.
💢They perform intensive erosional activity in their upper courses and carry huge loads of silt and sand. In the middle and the lower courses, these rivers from meanders, oxbow lakes, and many other depositional features in their floodplains.
💢Some of them originate in the central highlands and flow towards the west.
💢Most of the rivers of peninsular India originate in the Western ghats and flow towards the Bay of Bengal.
✳️The Himalayan Rivers
💢The major Himalayan rivers are the Indus, the Ganga and the Brahmaputra. These rivers are long, and are joined by many large and important tributaries. A river alongwith its tributaries may be called a river system.
✳️The Indus River System
💢The river Indus rises in Tibet, near Lake Mansarowar. flowing West, it enters India in the Ladakh district of Jammu and Kashmir.
💢The zaskar, the Nubra, the shyok and the hunza, are the tributaries in Kashmir.
💢The Indus flows through Baltistan and Gilgit and emerges from the mountains at Attock.
💢The satluj, the beas, the Ravi, the Chenab, and the Jhelum join together to enter the Indus near Mithankot in Pakistan.
💢With a total length of 2900 km, the Indus is one of the longest rivers of the world.
✳️The Ganga River System
💢The headwaters of the Ganga, called the 'Bhagirathi' is fed by the Gangotri Glacier and joined by the Alaknanda at Devaprayag in Uttarakhand.
💢Ganga meets the tributaries from the Himalayas such as Ghaghara, Gandak and kosi.
💢A major river Yamuna, arising from yamunotri glacier in the Himalayas, joins Ganga at Allahabad.
💢The Ghaghara, the Gandak and the Kosi rise in the Nepal Himalaya.
💢Other tributaries- Chambal, Betwa and Son- come from Peninsular uplands to join Ganga.
💢Farakka in West Bengal is the northernmost point of the Ganga Delta.
💢Ganga is joined by Brahmaputra and forms river Meghna which flows through Bangladesh to reach the Bay of Bengal.
💢The delta formed when the Ganga and the Brahmaputra flows into the Bay of Bengal is known as the Sunderban Delta.
💢The length of the Ganga is over 2,500 km and it develops large meanders in the downstream plain areas.
💢The Plains from Ambala to the Sunderban stretch over nearly 1800 km , but the fall in its slope is hardly 300 metres.
✳️The Brahmaputra River System
💢The Brahmaputra rises in Tibet east of Mansarowar Lake very close to the sources of the Indus and the satluj.
💢Most of its course lies outside the India.
💢On reaching the Namcha Barwa (7757m), it takes a 'U' turn and enters India in Arunachal Pradesh through a Gorge.
💢The tributaries that join Brahmaputra are Dibang, Lohit, and Kenula.
💢The Brahmaputra has a braided channel in its entire length in Assam to form many riverine islands. World's largest riverine Island is found in Brahmaputra.
💢Unlike other north Indian rivers, the Brahmaputra is marked by huge deposits of silt on its bed, causing the riverbed to rise.
✳️The Peninsular Rivers
💢The main water divide in Peninsular India is formed by the Western Ghats.
💢The major rivers of the Peninsular, such as the Mahanadi, the Godavari, the Krishna and the Kaveri flow eastwards and drain into the Bay of Bengal.
💢These rivers make deltas at their mouths.
💢The Narmada and the Tapi are the only long rivers, which flow west and make esturies.
💢The drainage basins of the peninsular rivers are comparatively smaller in size.
✳️The Narmada Basin
💢Rising in the Amarkantak hills, Narmada flows to create a gorge in marble rocks of Madhya Pradesh.
💢Narmada flows towards the west in a rift valley formed due to faulting.
💢Near Jabalpur it flows in the form of deep gorge in the marble rocks and Dhaudhar falls are picturesque locations.
💢The Narmada basin covers parts of Madhya Pradesh and Gujarat.
✳️The Tapi Basin
💢The Tapi rises in the Satpura ranges, in the Betul district of Madhya Pradesh.
💢It also flows in a rift valley parallel to the Narmada but it is much shorter in length.
💢Tapi flows through a basin that covers Madhya Pradesh, Gujarat and Maharashtra.
💢The main West flowing rivers are Sabarmati, Mahi, Bharathpuzha and Periyar.
✳️The Godavari Basin
💢Godavari begins in Nasik district of Maharashtra and is the largest peninsular river about 1500 km.
💢Its drainage basin is also the largest among the peninsular rivers.
💢Its basin covers parts of Maharashtra, Madhya Pradesh, Odisha and Andhra Pradesh.
💢The Godavari is joined by a number of tributaries, such as the Purna, the Wardha, the Pranhita, the Manjra, the Wainganga and the Penganga.
💢Because of its length and the area it covers, Godavari is also known as the Dakshin Ganga.
💢Godavari drains into the Bay of Bengal.
✳️The Mahanadi Basin
💢The Mahanadi rises in the highlands of Chhattisgarh. It flows through Odisha to reach the Bay of Bengal.
💢The length of the river is about 860 km. Mahanadi river basin is shared by Maharashtra, Odisha, Chhattisgarh and Jharkhand.
✳️The Krishna Basin
💢The 1400 km long Krishna river rises from a spring near Mahabaleshwar to reach the Bay of Bengal.
💢The Tungabhadra, the Kiyana, the Ghatprabha, the Musi and the Bhima are some of its tributaries.
💢The Krishna basin is shared by Maharashtra, Karnataka, and Andhra Pradesh.
✳️The Kaveri Basin
💢The Kaveri rises in the Brahmagri range of the Western Ghats and it reaches the Bay of Bengal in South of Cuddalore in Tamilnadu.
💢The total length of the river is about 760 km.
💢Its main tributaries are Amravati, Bhavani, Hemavati and Kabini.
💢Its basin drains parts of Karnataka, Kerala and Tamilnadu.
💢Other smaller rivers like the Damoder, the Brahmani, the Baitarni and the Subarnrekha.
✳️Lakes
💢The valley of Kashmir and the famous Dal Lake, the houseboats and shikaras,
which attract thousands of tourists every year.
💢Most lakes are permanent while other contain water only during the rainy season.
💢Some lakes are result of the action of glaciers and ice sheets and some may have been formed by wind, river action and human activities.
💢A meandering river across a floodplain forms cut-offs that later develops into ox-bow lakes.
💢The Sambhar Lake in Rajasthan, which is a salt water lake. Its water is used for producing salt.
💢Glacial lakes are formed when glaciers dig out a basin which is later filled with snowmelt.
💢Some lakes like Wular Lake in Jammu and Kashmir result from tectonic activity.
💢Apart from natural lakes, the damming of the rivers for the generation of hydel power has also led to the formation of lakes, such as Guru Gobind Sagar (Bhakra Nangal Project).
💢Lakes help to regulate river water flow, prevent flooding, aid to develop hydropower, moderate climate, maintain aquatic ecosystem, enhance natural beauty, develop tourism and provide recreation.
✳️Role of Rivers In The Economy
💢Rivers are natural sources of water. Settlements on the river banks have developed into cities.
💢Rivers are used for irrigation, navigation, hydropower generation, all Vital for India, an agricultural economy.
✳️River Pollution
💢Quality of river water is affected by the growing domestic, municipal,industrial and agricultural demand.
💢A heavy load of untreated sewage and industrial effluents are emptied into the river affecting the river's self- cleasing property.
💢Concern over rising pollution in our rivers led to the launching of various action plans to clean the rivers.
✳️Some Important Points
💢The world's largest drainage basin is of the Amazon river.
💢According to the regulation of the Indus Water Treaty (1960) ,India can use only 20% of the total water carried by the Indus river system. This water is used for irrigation in Punjab, Haryana and the southern and the Western parts of Rajasthan.
💢The Namami Ganga programme is an Integrated Conservation Mission approved as a 'flagship' programme by the union Government in June 2014 to accomplish the twin objectives of effective abatement of pollution, conservation and rejuvenation of the national river, Ganga.
💢The Sundarban Delta derived its name from the sundari tree, which grows well in marshland.
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