B D Dhawan The Gangetic basin accounted for two thirds of the tubewell irrigation of the country in 1972-73. Together with the Indus basin, the share was 95 per cent of the national tubewell-irrigated area. Within these two basins, covering the vast plains of the north, the development of tubewell irrigation diminishes in force and concentration as one moves from Punjab, Haryana, and west UP in the west to east UP, Bihar and West Bengal in the eastern plains.