The Himalayan Rivers: Indus, Ganga and Brahmaputra

Himalayan rivers rise in or near the Himalayas, flow through deep gorges in the mountains, and then spread across the northern plains. They are perennial, because they are fed both by rain and by melting snow and glaciers, and they carry large volumes of water and silt. Their courses are long, their basins are vast, and they cross national borders, so they are at once a source of irrigation and power, a cause of floods, and a subject of diplomacy. The three great systems are the Indus, the Ganga and the Brahmaputra.

The Indus rises in Tibet, flows through Ladakh and then through Pakistan to the Arabian Sea. Within India, its main tributaries are the Jhelum, Chenab, Ravi, Beas and Sutlej, which drain Punjab and surrounding regions. The Indus Waters Treaty of 1960 between India and Pakistan allocated the eastern rivers (Ravi, Beas, Sutlej) largely to India and the western rivers (Indus, Jhelum, Chenab) largely to Pakistan, with limited uses allowed to each side on the other's rivers. The treaty has survived wars and crises, which is why it is often cited as an example of durable river cooperation, even though its interpretation remains contested at times.

The Ganga rises as the Bhagirathi from the Gangotri glacier in Uttarakhand and becomes the Ganga at Devprayag, where it meets the Alaknanda. It flows eastwards through the northern plains, joined by the Yamuna, Ghaghara, Gandak and Kosi, among others, and reaches the Bay of Bengal through a vast delta shared with the Brahmaputra. At about 2,525 kilometres, it is the longest river in India by length within the country. Its plain is among the most densely populated and intensively farmed regions on Earth, and its water supports irrigation, industry, cities and fisheries, while also carrying heavy pollution loads from sewage, industry and agriculture.

The Brahmaputra rises as the Yarlung Tsangpo in Tibet, enters India through Arunachal Pradesh as the Siang or Dihang, and flows through Assam as the Brahmaputra before entering Bangladesh. Its total length is about 2,900 kilometres, of which about 916 kilometres lie in India. In Assam it is a braided river, splitting into many channels around shifting sandbars, and its floods, fed by monsoon rain and Himalayan melt, are among India's most destructive and most fertile, depositing silt across the valley each year. For civil studies, Himalayan rivers show why water policy cannot stop at a state border: the river's geography is international, its floods are regional, and its management needs data, dams, embankments and diplomacy together.