Surface water resources are highest in

Surface water resources in India are primarily concentrated in the northern river basins. The Ganga, Brahmaputra, and Barak river systems collectively account for approximately 60 percent of the total surface water resources of the country [3]. The Ganga basin alone is characterized by vast surface water bodies and significant annual flow, supported by high precipitation in its Himalayan catchment areas [3]. While the Brahmaputra has the highest discharge, the Ganga plains represent the most extensive region with high surface water availability and the richest underground water resources, containing about 44% of India's groundwater [4]. In contrast, although south Indian rivers like the Godavari and Krishna have been more extensively harnessed, their total volume remains lower than the northern perennial systems [3]. The Indus plains (eastern rivers) contribute a smaller fraction, with an average annual availability of approximately 47.30 BCM .

Sources

1. [3] Geography of India ,Majid Husain, (McGrawHill 9th ed.) > Chapter 3: The Drainage System of India > 7. The Ganga Brahmaputra Alluvial Province > p. 44
2. [1] Geography of India ,Majid Husain, (McGrawHill 9th ed.) > Chapter 3: The Drainage System of India > Inland Water Resources of India > p. 33
3. [4] https://cwc.gov.in/sites/default/files/reportwaterresourcesassessmentofindia2024_1.pdf