Drainage System in India

India’s river systems are primarily divided into two main categories: the Himalayan River System and the Peninsular River System, each with distinct origins, characteristics, and drainage areas.

The Himalayan Rivers

• Perennial rivers flow year-round, sourced from glaciers and rainfall.
• Young, erosive rivers cut through mountains, creating gorges.
• Predate Himalayas formation and drain southern and northern mountain ranges.
• Create features like floodplains, meanders, oxbow lakes, and other depositional landforms.

Three main river systems form the Himalayan drainage system:

1. Indus River System
2. Ganga River System
3. Brahmaputra River System

Indus River System

• The Indian subcontinent’s westernmost river system is 2880 km long.
• It rises 5,180 meters from a glacier close to Lake Mansarovar and is known in Tibet as Sing Khamban.
• flows across Ladakh and Baltistan in a northwesterly direction between the Zaskar and Ladakh peaks.
• The principal tributaries are Chenab, Sutlej, Beas, and Ravi.
• India and Pakistan’s water sharing is governed under the 1960 Indus Water Treaty.

Tributaries of the Indus:

• Jhelum: Originates from Sheshnag Lake in Kashmir, flows through Wular Lake near Srinagar, and enters Pakistan, where it joins the Chenab.
• Chenab: The largest tributary, rising at Bara-Lacha La pass, formed by the Chandra and Bhaga streams.
• Ravi: Originates near the Rohtang Pass in Himachal Pradesh, flowing through the Chambal Valley before joining the Chenab.
• Beas: Begins from Beas Kund near Rohtang Pass, flows through Kullu valley, and joins the Sutlej.
• Sutlej: Originates from the Rakas Lake near Mansarovar Lake in Tibet, enters India through Shipki La Pass.

The Ganga River System

The Ganga River originates from the Gangotri Glacier near Gaumukh in Uttarakhand at an altitude of 3900 meters. The river begins as two headstreams, the Alaknanda and Bhagirathi, which converge at Devprayag.

The Ganga travels through Uttarakhand, Uttar Pradesh, Bihar, and West Bengal, covering a distance of about 2,525 kilometers in India, and ends at Farraka, the northernmost point of the Ganga delta. The Bhagirathi-Hooghly, a distributary of the Ganga, flows southward through the deltaic plains to the Bay of Bengal. The Padma Ganga branch, entering Bangladesh, merges with the Brahmaputra River at Goalundo, forming the Yamuna downstream.

Tributaries of the Ganga:

• Yamuna: The longest and most important tributary, originating from Yamunotri Glacier in the Uttarkashi district. It flows parallel to the Ganga and joins it at Allahabad (Prayag).
  • Major tributaries of the Yamuna include Chambal, Sind, Betwa, and Ken.
• Gandak: Originates near the Sino-Nepal border, draining central Nepal and entering India.
• Kosi: Rising from the Nepal Himalayas, it includes the Sunkosi, Tamakoshi, Arun, and Tamor Kosi tributaries.
• Damodar: Flows along the eastern boundary of the Chhotanagpur Plateau, joining the Ganga distributary Hooghly after passing through Jharkhand and West Bengal. The Damodar Valley Corporation has been managing the area, previously known as the “Sorrow of Bengal,” through dam projects.
• Son: Originates from the Amarkantak Plateau and is a significant south bank tributary of the Ganga, joining the Ganga at Arrah in Bihar.
• Mahananda: A tributary from the Darjeeling hills, joining the Ganga as its last left bank tributary in West Bengal.
• Rāmgangā: A left bank tributary that rises near Nainital and joins the Ganga near Farrukhabad.
• Gomati: Originates from the Gomati Fall in the Pilibhit district of Uttar Pradesh and joins the Ganga at Ghazipur.

Each of these rivers contributes significantly to the water system of the Ganga, supporting agriculture and sustaining millions of people living in its basin.

The Brahmaputra River System

• The Brahmaputra River originates in the Chemayungdung glacier of the Kailash range near Lake Mansarovar in Tibet. 
• TsangPo River Overview
• Flows eastward across dry, flat southern Tibet.
• Divided from Lake Mansarovar by Mariam La Pass.
• Major tributary: Raga Tsangpo, Tibet.

• In Assam, braid channels generate a number of river islands, the greatest of which is Majuli.
• After Namcha Barwa, does a U-turn and enters India via the Dihang Gorge at Sadiya.
• It is joined by the Dihang and Lohit rivers, which contribute to the creation of the Brahmaputra in Assam.
• Travels 750 kilometres in the Assam Valley, receiving water from Subansiri, Manas, and Sankosh.
• Carries a considerable amount of water and silt, and is recognised for its high flow and wide channel.
• A major tributary of the Brahmaputra is the Tista River.

The Peninsular Rivers

The rivers of the Peninsular India, unlike the Himalayan rivers, have mature drainage systems that reflect their age. The region is characterized by broad, graded, shallow valleys and rivers that have fixed courses and minimal meandering. These rivers also have non-perennial flows. The Western Ghats act as the water divide between the East and West flowing rivers of Peninsular India.

Peninsular rivers are classified into two categories based on the direction of their flow:

1. West Flowing Rivers: These rivers flow towards the Arabian Sea.
   • They include the Narmada, Tapi, Mahi, and smaller streams such as Sabarmati and Periyar. These rivers typically flow through rift valleys, creating estuaries due to their fast flow and steep slopes.
     • The Narmada flows through a rift valley between the Vindhya and Satpura mountain ranges and drops in height to create the famous Dhuandhar Falls.
     • The Tapi rises from the Satpura range and flows westward into the Gulf of Khambat.
     • The Mahi flows from the Vindhyas and enters the Gulf of Khambat.
     • The Sabarmati originates in the Aravallis and flows into the Arabian Sea.
2. East Flowing Rivers: These rivers flow towards the Bay of Bengal, forming deltas at their mouths.
   • Major East-flowing rivers include the Mahanadi, Godavari, Krishna, and Cauvery, along with smaller rivers such as the Brahmani, Subarnarekha, and Pennar. These rivers flow across gentler landscapes, contributing to delta formation.
     • The Godavari is the largest East-flowing river, originating in the Western Ghats and passing through Maharashtra, Madhya Pradesh, Chhattisgarh, Odisha, and Andhra Pradesh. It is known as the “Dakshin Ganga” or “Vridha Ganga” and has numerous tributaries.
     • The Krishna rises in the Mahabaleshwar hills and flows through Maharashtra, Karnataka, and Andhra Pradesh before reaching the Bay of Bengal.
     • The Cauvery is a major river in Karnataka and Tamil Nadu, originating in the Western Ghats and flowing towards the Bay of Bengal.
     • The Mahanadi rises in Madhya Pradesh and flows through Odisha and Chhattisgarh, forming an important river basin.