GEOMORPHOMETRIC ANALYSIS OF TOPOGRAPHY FOR UNDERSTANDING ALPINE GLACIER DYNAMICS IN THE HIMALAYA

Recent controversy regarding climate change and glacier recession, coupled with new data showing advancing and surging glaciers in the western Himalaya, has revealed the complexity related to the coupling of climate and mountain geodynamic systems. There is a paucity of field data regarding glacier ablation and accumulation rates, ice-flow velocities, debris-cover variations, and mass balance data from benchmark glaciers. Little is known about these complexities and the spatial variability of glacier dynamics, although climate-topography-glacier feedback mechanisms are thought to play a role in glacier fluctuations that have been observed across regions and the entire Himalaya. Consequently, our research objective is to examine the spatial variations of multi-scale topographic parameters that regulate supra-glacial debris production, surface irradiance and ablation, and glacial geomorphological conditions. Satellite imagery and digital elevation data (STRM 90 m and ASTER G-DEM 30 m) were used to assess alpine glaciers conditions such as estimates of glacier retreat/advance rates, glacier ice-velocity profiles, and glacier geometry. Analysis of the topography was used to generate local and multi-scale topographic parameters that regulate the direct and diffuse-skylight irradiance components. Results indicate that unique spatio-temporal patterns of direct irradiance and meso-scale topographic shielding are related to glacier debris-load conditions, the presence of ice-flow velocity anomalies, and glacial histories of erosion and relief production. Collectively, these results demonstrate that topography can explain the high-frequency spatial variability of various aspects of glacier dynamics, and that microclimatic conditions in the Himalaya must be considered when interpreting glacier fluctuations as a signal of regional climate change. More research is required to quantify the magnitude of topographic forcing.