Chapters :
______________________________________
Introduction :
Drainage system: Refers to the river system of an area, where small streams from various directions converge to form a main river, eventually draining into a large water body like a lake, sea, or ocean.
Drainage basin: The area drained by a single river system, encompassing all the land and waterways that contribute to the flow of a particular river.
Water divide: An elevated area such as a mountain or upland that separates two drainage basins, serving as a boundary where water flows in opposite directions.
Drainage systems in India :
Drainage systems of India are influenced by the broad relief features of the subcontinent, leading to two major groups of rivers: Himalayan rivers and Peninsular rivers.
Himalayan rivers: Mostly perennial, with continuous water flow throughout the year, receiving water from rain and melted snow from the mountains. Major rivers like the Indus and Brahmaputra originate from the north of the mountain ranges, cutting through the mountains to form gorges. They exhibit intensive erosional activity in their upper courses and form depositional features like meanders, oxbow lakes, and deltas in their floodplains.
Peninsular rivers: Many are seasonal, with flow dependent on rainfall, leading to reduced water flow during the dry season. These rivers have shorter and shallower courses compared to Himalayan rivers. Some originate in the central highlands and flow westward. Most rivers of peninsular India originate in the Western Ghats and flow towards the Bay of Bengal
NCERT Class 9 Geography | Chapter 3 | Drainage
Ganga River System:
Tributaries: Joined by several tributaries from the Himalayas, including major rivers like the Yamuna, Ghaghara, Gandak, and Kosi.
Yamuna: Rises from the Yamunotri Glacier, flows parallel to the Ganga, and meets it at Allahabad.
Himalayan Tributaries: Ghaghara, Gandak, and Kosi originate in Nepal Himalaya, causing annual floods in the northern plains.
Peninsular Tributaries: Chambal, Betwa, and Son rise from semi-arid areas and join the Ganga.
Course: Flows eastwards till Farakka in West Bengal, where it bifurcates into the Bhagirathi-Hooghly and the mainstream, which later joins the Brahmaputra in Bangladesh to form the Meghna.
Delta: Sundarban Delta, formed by the Ganga and Brahmaputra, flows into the Bay of Bengal.
Length: Over 2500 km.
Brahmaputra River System:
Origin: Rises in Tibet, flows parallel to the Himalayas, and enters India through Arunachal Pradesh.
Tributaries: Joined by the Dibang, Lohit, and other tributaries to form the Brahmaputra in Assam.
Characteristics: Carries less water and silt in Tibet, but in India, carries a large volume of water and silt, resulting in a braided channel and numerous riverine islands in Assam.
Floods: Causes widespread devastation during the rainy season in Assam and Bangladesh due to annual floods.
Riverine Island: Majuli, the world's largest riverine island formed by the Brahmaputra.
Channel Shifting: Frequently shifts its channel, depositing huge amounts of silt on its bed.
The Peninsular Rivers :
Water Divide in Peninsular India:
Formed by the Western Ghats, running from north to south, close to the western coast.
Major rivers like Mahanadi, Godavari, Krishna, and Kaveri flow eastwards into the Bay of Bengal.
Rivers Flowing Eastwards:
Mahanadi Basin:
Origin: Amarkantak Hills in Madhya Pradesh.
Characteristics: Flows westward, creating picturesque locations like Marble Rocks and Dhuadhar Falls.
Basin: Covers parts of Madhya Pradesh and Gujarat.
Tapi Basin:
Origin: Satpura ranges in the Betul district of Madhya Pradesh.
Characteristics: Flows in a rift valley parallel to Narmada but shorter in length.
Basin: Covers parts of Madhya Pradesh, Gujarat, and Maharashtra.
Godavari Basin:
Origin: Slopes of Western Ghats in Nasik district of Maharashtra.
Characteristics: Largest Peninsular river, draining into the Bay of Bengal.
Tributaries: Purna, Wardha, Pranhita, Manjra, Wainganga, Penganga.
Basin: Covers parts of Maharashtra, Madhya Pradesh, Odisha, and Andhra Pradesh.
Mahanadi Basin:
Origin: Highlands of Chhattisgarh.
Characteristics: Flows through Odisha to reach the Bay of Bengal.
Basin: Shared by Maharashtra, Chhattisgarh, Jharkhand, and Odisha.
Krishna Basin:
Origin: Spring near Mahabaleshwar.
Characteristics: Flows for about 1400 km, reaching the Bay of Bengal.
Tributaries: Tungabhadra, Koyana, Ghatprabha, Musi, Bhima.
Basin: Shared by Maharashtra, Karnataka, and Andhra Pradesh.
Kaveri Basin:
Origin: Brahmagri range of the Western Ghats.
Characteristics: Flows about 760 km, reaching the Bay of Bengal.
Tributaries: Amravati, Bhavani, Hemavati, Kabini.
Basin: Drains parts of Karnataka, Kerala, and Tamil Nadu.
West Flowing Rivers:
Narmada and Tapi are the only long rivers flowing west and forming estuaries.
Coastal Plains:
Coastal rivers Sabarmati, Mahi, Bharathpuzha, and Periyar flow west and have short courses.
Lakes :
Importance of Lakes:
Lakes play a crucial role in attracting tourists to various destinations.
They offer recreational activities like boating, swimming, and water games.
Lakes contribute to the aesthetic appeal of tourist spots like Srinagar and Nainital.
Variety of Lakes in India:
Vary in size and characteristics; some are permanent while others are seasonal.
Formation: Glacial action, river meandering, coastal processes, and human activities.
Types of Lakes:
Glacial Lakes: Formed by glaciers digging out basins later filled with snowmelt.
Oxbow Lakes: Formed by meandering rivers across floodplains.
Coastal Lagoons: Formed by spits and bars along coastal areas.
Significant Lakes in India:
Wular Lake: The largest freshwater lake in India, formed by tectonic activity.
Dal Lake, Bhimtal, Nainital, Loktak, Barapani: Important freshwater lakes.
Man-Made Lakes:
Formed by damming rivers for hydel power generation, e.g., Guru Gobind Sagar.
Value of Lakes:
Regulate river flow, preventing flooding during heavy rains and maintaining even flow during the dry season.
Potential for hydel power generation.
Moderate local climate, enhance natural beauty, support aquatic ecosystems, and promote tourism and recreation.
Roles of river in economy :
Rivers have played a crucial role throughout human history, providing essential water resources for various activities.
Settlements along riverbanks have evolved into major cities over time.
Utilizing rivers for irrigation, navigation, and hydro-power generation holds special importance, especially in countries like India, where agriculture is the primary livelihood for most of the population.
River Pollution :
Growing demands for water from rivers due to domestic, municipal, industrial, and agricultural needs impact water quality.
Increased water extraction reduces river volume.
Untreated sewage and industrial effluents further degrade water quality and impair the self-cleansing capacity of rivers.
Urbanization and industrialization exacerbate pollution, hindering natural dilution processes.
Various action plans have been launched to address rising river pollution.
Pollution in rivers affects human health and can lead to various illnesses.
Consider the consequences of life without access to fresh water.
Organize a classroom debate on the topic to explore different perspectives and solutions