Glacier area variation in Uttarakhand Himalaya: Investigating trends and influencing factors

Understanding the intricate interplay between topography and glacier changes is vital for predicting future water resources and addressing the impacts of climate change. This study examines changes in glacier area in the Uttarakhand Himalayan region, where the River Ganga originates, between 2000 and 2023 using high-resolution satellite imagery. A manual digitization process was employed to delineate the glacier boundaries of 116 glaciers for the years 2000 and 2023. Multivariate regression analysis was then conducted to identify and quantify the controlling topographical and morphological parameters. The analysis revealed significant reductions in total glacier area, decreasing from 979.05 ± 46.89 km2 in 2000 to 957.60 ± 13.67 km2 in 2023, with an overall deglaciation rate of 0.095% per year, highlighting variability in glacier responses. This variability is driven by a complex interplay of mainly slope, shape index, glacier elevation and surface ice velocity. Among these factors, the shape index emerged as the most influential. Glaciers with a higher shape index (more elongated) were found to be more stable than those with a lower shape index (more circular). A 10% difference in shape index results in a glacier with a higher shape index losing 0.112% per year less area compared to a glacier with a lower shape index. The second controlling parameter is glacier slope; glaciers with a 10% steeper slope lost 0.11% per year less area compared to those with a gentler slope. The other two parameters showed some minor impact on glacier area variation in the sample glaciers but not across the entire Uttarakhand region.