Heterogeneity in glacio-hydrological processes and estimation of different components in streamflow from central Himalayan glaciers

Abstract

Study regionThe study region includes two glaciers from Alaknanda and Bhagirathi river basins in Central Himalaya. Study focusThe study focuses on the analysis of high-resolution isotopic data sets of different components of the streamflow with ground-based meteorological observations from Automatic Weather Stations (AWSs) at two glaciers (∼4000 m asl). New hydrological insights for the regionThe glaciers in the Himalaya are difficult to access due to their topography and climate and require complicated logistics to work in the region. Hence, the understanding of hydrological processes in this region is limited. The debris cover (sublimation of surface ice), orientation and microclimatic conditions (temperature, wind and rain) of the two glaciers control the isotope signatures of the glacier surface ice in the Himalayan region, indicating heterogeneity and complexity in the isotopic compositions. The studies estimating the contribution of different components to the streamflow downstream using generalized values of stable isotopes (glacier ice, snow) are complicated, as several glaciers contribute to the total runoff in large basins. The stable isotopes of streamflow indicate the contribution of snow and ice melt during early ablation (May-Jun.); rainfall and ice melt during the ISM (Jul.-Aug.) and ice melt during late ablation (Sep.-Oct.). The contribution of snow-glacier melt and rainfall for the ablation season (Jun.-Oct.) was 89% and 11%, respectively. The separation of the hydrograph is complex, site and time-specific, which needs attention.