• Though the river originates in India and flows east, ending its journey in Bangladesh, the Ganga basin is spread over 1,093,400 sq km, picking up water from 4 countries

• The large part of the water is contributed from north by perennial sources in the Himalaya. The catchment on the south and west contribute seasonalyy, during the monsoon. Interesting: note the large catchment Rajasthan and Madhya Pradesh provide.

• 80 per cent of the total run-off in Ganga flows only in four months: June to September. A quick look at the average annual rainfall over different cities in the basin shows its spatial nature.

Annual rainfall: West to east along the Ganga basin