Input by Indian rivers into the world oceans

Abstract

The chemical, sediment and total load carried by the major river basins in India—Ganges, Brahmaputra, Indus (Jhelum), Godavari, Krishna, Narmada, Tapti, Mahnadi and Cauvery have been calculated, based partly on new set of data and partly on existing data. There is a significant amount of chemical load transported by all the Indian rivers, and for global mass transfer calculation, these cannot and should not be ignored. The chemical mass transfer during the monsoon is not surprisingly small, as would be expected for excess discharge and dilution controlled run-off. The sediment mass transfer from non-Himalyan rivers, all within the same range of magnitude, accounts for less than a tenth of that of the Ganges but during the monsoon, except for Cauvery, all the Indian rivers carry a sediment load of greater than 1000 ppm. The total mass transfer from the Indian subcontinent accounts for 6·5 per cent of the global transfer.

Except for the Ganges and the Brahmaputra, the erosion rates are similar for all Indian basins, independent of their size and these rates are agreeable with the continental earth average. The Ganges-Brahmaputra basin erosion rates are highest on the continental earth. Based on the average rate of denudation of the Indian subcontinent, the mean elevation of this landmass will be that of the present day mean sea level in 5 million years from now. The average denudation rate of 2·1 cm/100 years is different from the calculated average sedimentation rate of 2·1 cm/100 years is different from the calculated average sedimentation rate of 6·7 cm/100 years in the Bay of Bengal suggesting that an accurate erosion rate in the continent is needed to determine sedimentation rate in the oceans.

The chemical and sediment mass transfer rates appear to have a logarithmic linear relationship on a global scale, as against the reported negative logarithmic trend for North America alone.