Hydrological control of the surging behaviour of the Ghujerab River Head Glacier, Karakoram (2019-2023): Insights from high-temporal-resolution remote sensing monitoring

Study region: The northern region of the Karakoram Range. Study focus: Karakoram is a region in High Mountain Asia with many surge-type glaciers. This study employed over 200 high-temporal-resolution remote sensing images and investigated the variations in elevation and velocity of the Ghujerab River Head Glacier (GRHG) from 2019 to 2023. Furthermore, we elucidated the potential controlling mechanisms. New hydrological insights for the region: Our findings revealed that the GRHG, akin to typical surgetype glaciers in Karakoram, started to surge in the spring and finished surging in the summer, with a duration of less than two years. Throughout the surging process, the glacier transferred a mass of 0.11 +/- 0.003 km3 from the reservoir area to the receiving area, resulting in a thickening of 91.59 +/- 1.04 m at the glacier terminus and thinning of 11.78 +/- 1.04 m in the upper glacier. By analysing the mass balance and glacier surface albedo during surging, we proposed that climatic disturbances in the glacier region provided essential material inputs for the surge. Additionally, based on the seasonal evolution pattern of glacier flow velocity, we inferred a close correlation between surging and variations in subglacial hydrology. The duration of acceleration and deceleration during glacier surging, as well as a comparison with existing studies, further support our conclusion. Future research integrating multi-source remote sensing and onsite observations can support numerical simulations to quantitatively reveal the key processes occurring beneath and within glaciers during surge events.