Snow and glacier melt contributions and SLA-ELA relationship in himalayan basins

Abstract

Snow and glacier meltwater are critical hydrological components in the glacierized and snow-covered basins of the Himalaya-Karakoram (HK), yet their accurate quantification remains challenging due to limited in-situ observations in this remote and rugged terrain. This thesis aims to advance the understanding of meltwater dynamics, improve modelling approaches, and enhance glacier monitoring techniques using remote sensing to better assess hydrological responses of glacierized basins to climatic variability in the region. The thesis focuses on three glacierized basins situated in distinct climatic regimes of HK. In the western Himalaya, the Snowmelt Runoff Model (SRM) was applied in the Chandra-Bhaga Basin, using a data-rich reference catchment of Chhota Shigri Glacier to constrain key parameters from extensive field observations, while the remaining parameters were calibrated against observed discharge. Daily discharge simulations for 2003–2018 indicated that flow was primarily controlled by summer temperature in the Chhota Shigri Catchment and by summer SCA at the basin scale. Although parameters calibrated in the reference catchment produced good results at the catchment scale, their direct application to the basin scale resulted in substantial overestimation of discharge, indicating that the parameters are not transferable even within the same basin. In the central Himalaya, the long-term melt contributions and their climatic controls in the Gangotri Glacier System (GGS) were examined over 1980–2020, by applying a high-resolution glaciohydrological model Spatial Processes in Hydrology (SPHY) forced with Indian Monsoon Data Assimilation and Analysis reanalysis data.