The cryosphere constitutes an important subset of the hydrosphere. The Himalayan cryosphere is a significant contributor to the hydrological budget of a large river system such as the Ganges. Basic data on the cryosph...The cryosphere constitutes an important subset of the hydrosphere. The Himalayan cryosphere is a significant contributor to the hydrological budget of a large river system such as the Ganges. Basic data on the cryosphere in the Himalaya is inadequate and also has large uncertainties. The data on glacial melt component in the Himalayan rivers of India also shows high variability. The Gangotri glacier which constitutes nearly a fifth of the glacierized area of the Bhagirathi basin represents one of the fastest receding, large valley glaciers in the region which has been surveyed and monitored for over sixty years. The availability of measurement over a long period and relatively small glacier-fed basin for the Bha- girathi river provides suitable constraints for the measurement of the glacial melt fraction in a Himalayan river. Pre- and post-monsoon samples reveal a decreasing trend of depletion of 0180 in the river water from glacier snout （Gaumukh） to the confluence of the Bhagiratbi river with the Alaknanda river near Devprayag. Calculations of existing glacial melt fraction （-30% at Rishikesh） are not consistent with the reported glacial thinning rates. It is contended that the choice of unsuitable end-members in the three component mixing model causes the overestimation of glacial melt component in the river discharge. Careful selection of end members provides results （-11% at Devprayag） that are consistent with the expected thinning rates.展开更多
基金Science and Engineering Research Board,Department of Science and Technology,Government of India is acknowledged for funds for the project entitled"Finger printing of glacial melt water in the Ganga basin-implications for modeling of hydrological cycle in a Himalayan river system"grant number NO.SR/DGH-46/2012 which supported work for this paper
文摘The cryosphere constitutes an important subset of the hydrosphere. The Himalayan cryosphere is a significant contributor to the hydrological budget of a large river system such as the Ganges. Basic data on the cryosphere in the Himalaya is inadequate and also has large uncertainties. The data on glacial melt component in the Himalayan rivers of India also shows high variability. The Gangotri glacier which constitutes nearly a fifth of the glacierized area of the Bhagirathi basin represents one of the fastest receding, large valley glaciers in the region which has been surveyed and monitored for over sixty years. The availability of measurement over a long period and relatively small glacier-fed basin for the Bha- girathi river provides suitable constraints for the measurement of the glacial melt fraction in a Himalayan river. Pre- and post-monsoon samples reveal a decreasing trend of depletion of 0180 in the river water from glacier snout （Gaumukh） to the confluence of the Bhagiratbi river with the Alaknanda river near Devprayag. Calculations of existing glacial melt fraction （-30% at Rishikesh） are not consistent with the reported glacial thinning rates. It is contended that the choice of unsuitable end-members in the three component mixing model causes the overestimation of glacial melt component in the river discharge. Careful selection of end members provides results （-11% at Devprayag） that are consistent with the expected thinning rates.
