River Basin Atlas of India

India, the seventh-largest country in the world, holds four per cent of the world's freshwater resources and supports 17 per cent of the world population. The country receives 4,000 billion cubic meters (BCM) of water annually, with 1,869 BCM being available for use. Utilizable water includes 690 BCM from surface water and 433 BCM from groundwater, totalling 1,123 BCM.

The per capita water availability was 1,588 cubic meters per year in 2010 but was projected to decrease to 1,434 cubic meters by 2025 due to population growth. A significant portion of the water resources is used for irrigation, with India boasting 5,125 large dams and 1,894 major and medium irrigation projects as of 2007.

Initially, water resource projects were planned independently by different states without considering inter-state interactions. With increasing demand for water, integrated development of river basins has become essential, the atlas notes.

Under the India-Water Resource Information System (WRIS), the inland drainage area in Rajasthan is merged with the Indus Basin. The west-flowing rivers from Tapi to Tadri and Tadri to Kanyakumari (counted as separate basins in the Central Water Commissions classification) are combined into a single basin. Similarly, east-flowing rivers between Mahanadi and Godavari, Godavari and Krishna, and Krishna and Pennar, considered one basin by CWC, are treated as separate basins in India-WRIS due to their independent drainage into the Bay of Bengal.

That atlas also categorizes rivers between Pennar and Cauvery and those south of Cauvery as distinct basins. Rivers draining into Myanmar and Bangladesh are also recognized as separate basins. India-WRIS introduces new basins for the areas of north Ladakh, Lakshadweep, and Andaman and Nicobar Islands.

In India, 60 per cent of the Indus basin is found in Jammu and Kashmir, followed by Himachal Pradesh (16 per cent), Punjab (15.96 per cent) and the rest in Rajasthan, Haryana and Chandigarh. Overall, the river basin also spans Tibet, Afghanistan and Pakistan covering 1,165,500 square kilometres (sq. km). Around 321,289 sq. km of this is in India, representing 9.8 per cent of the country's area. The Indus River originates in Tibet near Mansarovar Lake and flows 2,880 kilometres to the Arabian Sea, with 1,114 kilometres in India. Its major tributaries in India include the Jhelum, Chenab, Ravi, Beas, and Satluj. Agricultural land covers 35.8 per cent of the basin. The Indus Water Treaty of 1960 governs water use, granting India unrestricted rights to the Ravi, Beas and Satluj rivers, the atlas notes.

The Ganga basin spans India, Tibet, Nepal and Bangladesh, covering an area of 1,086,000 sq. km. In India, its basin stretches across 861,452 sq. km, representing 26 per cent of the country's total area, and includes the states of Uttar Pradesh, Madhya Pradesh, Rajasthan, Bihar, West Bengal, Uttarakhand, Jharkhand, Haryana, Chhattisgarh, Himachal Pradesh, and Delhi. The Ganga originates from the Gangotri glacier in Uttarakhand and flows 2,525 kilometres to the Bay of Bengal. Key tributaries include the Yamuna, Son, Ramganga, Ghaghra, Gandak, Kosi, and Mahananda. The basin is predominantly covered by agricultural land – around 66 per cent of the total area.

The Brahmaputra basin spans 580,000 sq. km across Tibet, Bhutan, India and Bangladesh. In India, it covers 194,413 sq. km across six states. Originating from the Kailash ranges, the Brahmaputra flows 2,900 kilometres with 916 in India. Key tributaries of the river include the Lohit, Dibang and Teesta among others. The basin is 55.48 per cent forested and covered by water bodies over 5.79 per cent of its area. In terms of area, the basin extends mostly in Arunachal Pradesh (42 per cent) and Assam (36.3 per cent).

The Godavari basin covers 312,812 sq. km across Maharashtra, Andhra Pradesh, Chhattisgarh, Odisha and parts of Madhya Pradesh, Karnataka and Puducherry, making up 9.5 per cent of India's geographical area. The river originates from Trimbakeshwar in Maharashtra and flows 1,465 km to the Bay of Bengal. Key tributaries include the Pravara, Manjra, Purna, Penganga, Wardha, Wainganga, Indravati and Kolab. About 59.57 per cent of the basin is covered by agricultural land and 3.6 per cent by water bodies.

The Krishna basin spans 258,948 sq. km across Andhra Pradesh, Maharashtra, and Karnataka covering nearly 8 per cent of India's geographical area. The basin, bound by the Balaghat range, and the Eastern and Western Ghats, stretches 701 kilometres in length and 672 kilometres in width. The Krishna originates near Jor village in Maharashtra and flows 1,400 km to the Bay of Bengal. Key tributaries of Krishna include the Ghatprabha, Malprabha, Tungabhadra, Bhima, Musi and Munneru. The basin is predominantly agricultural (75.86 per cent) with 4.07 per cent covered by water bodies.

The Tapi basin extends 65,145 sq. km across Madhya Pradesh, Maharashtra and Gujarat. Located in the Deccan Plateau, it is bound by the Satpura range, Mahadev hills, the Ajanta range, Satmala hills and the Arabian Sea. The basin is characterized by forested hills and fertile plains. Tapi, the second-largest westward draining river of the peninsula, originates near in Madhya Pradesh and flows 724 kilometres to the Arabian Sea. Key tributaries of Tapi include the Suki, Gomai, Arunavati, Vaghur, Girna and Purna among others.

The Narmada basin covers 98,796 sq. km across Madhya Pradesh, Gujarat, Maharashtra and Chhattisgarh – roughly three per cent of India's geographical area. It is bordered by the Vindhyas, the Satpuras, the Maikala range and the Arabian Sea. Narmada, the largest west-flowing river in peninsular India, rises near Amarkantak in Madhya Pradesh and flows 1,312 km to the Arabian Sea. Its key tributaries include the Burhner, Banjar, and Shakkar among others.

Focus and Factoids by Arunima Mandwariya.