Abstract
Supraglacial ponds play a significant role in the mass loss of many debris-covered glaciers in the Himalaya. Glacier surface topography and debris flux conditions are thought to govern supraglacial ponding and drainage. Existing studies, however, have not adequately investigated the relationships and feedbacks between meltwater production, debris transport, topographic evolution and ponding, because field measurements are limited in time and space, and most existing models either neglect these processes or use oversimplified assumptions. Such limitations restrict our understanding of supraglacial hydrology and introduce uncertainties in our assessments of glacier sensitivity to climate forcing. This study develops a more comprehensive numerical model to provide insights into the couplings between topographically-controlled surface ablation, meltwater drainage, ponding, and gravitational debris transport under radiative forcing. We investigate supraglacial ponding and drainage dynamics in response to different topographic and debris flux conditions through numerical simulations based on Baltoro Glacier in the Karakoram and several hypothetical scenarios. Results suggest that: 1) Supraglacial ponds make a significant contribution to the total ice loss (more than 20 %) in the lower-mid ablation zone over one ablation season, which elevates the glacier's nonlinear response to radiative forcing. 2) Gravitational debris transport has a non-negligible control on the growth rate of supraglacial ponds by governing debris thickness and ablation rates on the ice-cliffs around ponds. 3) Glacier surface gradient and local topographic depressions control pond formation by affecting supraglacial water storage and drainage. Our simulations provide a possible explanation to the abundance of ponds in the mid ablation zone where slope is gentle and more local depressions are present. These findings may contribute to more accurate predictions of future glacier changes in response to climate change.
Highlights
Supraglacial ponds play an important role in glacier mass-balance and glacial hydrology (Fountain and Walder, 1998; Sakai 20 et al, 2000; Wessels et al, 2002; Cuffey and Paterson, 2010; Miles et al, 2016, 2018; Huo et al, 2021a), and they are likely to grow rapidly on debris-covered glaciers (DCGs) given projections of atmospheric warming (Benn et al, 2001; Gibson et al, 2017), which will have a significant impact on regional water resources and hydro-power supply (Wessels et al, 2002; Dobreva et al, 2017; Bush et al, 2020)
Results suggest that: 1) Supraglacial ponds make a significant contribution to the total ice loss in the lower-mid ablation zone over one ablation season, which elevates the glacier’s nonlinear response to radiative forcing
Little quantitative knowledge is known about how debris flux and surface topography control the ponding dynamics, as multiple processes and feedback mechanisms associated with pond formation and evolution have not been accounted for in existing glacier models
Summary
Supraglacial ponds play an important role in glacier mass-balance and glacial hydrology (Fountain and Walder, 1998; Sakai 20 et al, 2000; Wessels et al, 2002; Cuffey and Paterson, 2010; Miles et al, 2016, 2018; Huo et al, 2021a), and they are likely to grow rapidly on debris-covered glaciers (DCGs) given projections of atmospheric warming (Benn et al, 2001; Gibson et al, 2017), which will have a significant impact on regional water resources and hydro-power supply (Wessels et al, 2002; Dobreva et al, 2017; Bush et al, 2020). A better understanding of the processes and factors that govern supraglacial pond formation and evolution is critical 30 for a more accurate assessment of regional water resources and geohazard conditions
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
