Studies of glacier mass balance processes and the climate response of glacier fed rivers in the himalaya

Abstract

The climate change impact on the water security of the glacierised catchments of High Mountain Asia can potentially be amplified by the shrinkage of snow and ice reserve However uncertainties in quantitative descriptions of cryospheric processes those of input data and a serious lack of field observations compromise the predictability of Himalayan glaciers and glacier fed rivers In order to address some of the aspects of the broader issues we choose specific problems related to the mass balance processes of glaciers and the climate response of glacier fed rivers in the Himalaya In the thesis we develop modelling and field based novel methods to quantify important processes related to the accumulation and ablation of ice on debris covered Himalayan glaciers As changing glacier runoff is the key to understanding the future changes in Himalayan rivers we analyse the climate response of the runoff of glacier fed rivers The major outcomes of the thesis are the following 1 Avalanching is a significant contributor to the accumulation of snow and ice on a large class of Himalayan glaciers Field based glaciological mass balance measurement ignores the avalanche contribution No attempts have been made to quantify the net avalanche contribution to mass balance in the Himalaya We first discuss diagnostic criteria to identify strongly avalanche fed glaciers and then develop an approximate method to quantify the magnitude of the avalanche contribution to the accumulation Our simulations show that in three well studied Himalayan glaciers 95 of the total accumulation is controlled by avalanches This study led to the first quantification of avalanches and the associated biases in the glaciological mass balance of these glaciers Also point out the strong control of avalanches on the dynamics of these glaciers 2 Sub seasonal ablation measurement by glaciological method involves tremendous human effort and often poses serious logistical challenges on debris covered Himalayan glaciers Measurement of vertical temperature p