Simulating Seasonal Evolution of Subglacial Hydrology at a Surging Glacier in the Karakoram

Neosha Gupta Narayanan, Aleah Nicholson Sommers , Winnie Chu, Jakob Steiner, Muhammad Adnan Siddique, Colin R. Meyer, Brent Minchew

Glacier motion, retreat, and glacier hazards such as surges and glacial lake outburst floods (GLOFs) are likely underpinned by subglacial hydrology. Recent advances in subglacial hydrological modeling allow us to shed light on subglacial processes that lead to changes in ice mass balance and GLOFs in High Mountain Asia (HMA). We present the first application of the SHAKTI subglacial hydrology model on an alpine glacier. Shishper Glacier, our study site, is a surge-type glacier in northern Pakistan that exhibits concurrent GLOFs which endanger local communities and infrastructure. The subglacial hydrological system undergoes transitions between inefficient to efficient drainage and back during spring and fall, supporting previous observations of spring and fall speedups of glaciers in the region. We also conclude that subglacial hydrology, while important in sliding dynamics, cannot provide a standalone explanation for surging, implicating a need for coupled hydrological and ice dynamics modeling of surge conditions. This work demonstrates the potential of using ice sheet models for alpine glaciology and provides a new nucleus for modeling of glacial hazards in alpine environments.