The 2015 Surge of Hispar Glacier in the Karakoram

Abstract

Abstract:The Karakoram mountain range is well known for its numerous surge-type glaciers of which several have recently surged or are still doing so. Analysis of multi-temporal satellite images and digital elevation models have revealed impressive details about the related changes (e.g., in glacier length, surface elevation and flow velocities) and considerably expanded the database of known surge-type glaciers. One glacier that has so far only been reported as impacted by surging tributaries, rather than surging itself, is the 50 km long main trunk of Hispar Glacier in the Hunza catchment. We here present the evolution of flow velocities and surface features from its 2015/16 surge as revealed from a dense time series of SAR and optical images along with an analysis of historic satellite images. We observed maximum flow velocities of up to 14 m d −1 (5 km a −1 ) in spring 2015, sudden drops in summer velocities, a second increase in winter 2015/16 and a total advance of the surge front of about 6 km. During a few months the surge front velocity was much higher (about 90 m d −1 ) than the maximum flow velocity. We assume that one of its northern tributary glaciers, Yutmaru, initiated the surge at the end of summer 2014 and that the variability in flow velocities was driven by changes in the basal hydrologic regime (Alaska-type surge). We further provide evidence that Hispar Glacier has surged before (around 1960) over a distance of about 10 km so that it can also be regarded as a surge-type glacier.

Brief communication: The Khurdopin glacier surge revisited – extreme flow velocities and formation of a dammed lake in 2017

“…Future field observations should focus on finding possible evidence for these processes and possible feedback processes, especially related to the deformation of water-saturated granular base material that could explain these extreme acceleration rates and peak velocities (Damsgaard et al, 2015). The surface velocities observed during the peak surge in May 2017 on Khurdopin Glacier are, together with the recently observed surge on the neighbouring Hispar Glacier (Paul et al, 2017), the fastest so far reported for the region. In their magnitude and rapid acceleration and deceleration they are comparable to similar bursts at the closely investigated Variegated Glacier (Kamb et al, 1985), where observations with even higher temporal resolution were available.…”

Extracting recent short-term glacier velocity evolution over Southern Alaska from a large collection of Landsat data

“…Georeference errors are compensated by the estimation of a polynomial bias 25 surface through areas outside glaciers (i.e., assumed stable). The glacier mask used for that purpose is from the Randolph Glacier Inventory (RGI) (Pfeffer et al, 2014). The resulting grids come in Universal Transverse Mercator (UTM) projection and if orthorectification errors are minimal, displacements for precise georeferencing require only horizontal movement of a few meters (generally <10 m).…”

“…Up to now, most studies of glacial velocity have had an emphasis on either spatial or temporal detail. When temporal detail 20 is present, studies focus on a single or a handful of glaciers (Scherler et al, 2008;Quincey et al, 2011;Paul et al, 2017). On the other hand, when regional assessments are the focus, the temporal resolution ranges from a single time stamp up to annual resolution (Copland et al, 2009;Dehecq et al, 2015;Rosenau et al, 2015).…”

“…for strong spatial velocity gradients), the smoothing can be supported by a glacier mask. In our case, this mask is a rasterization of the Randolph Glacier Inventory (Pfeffer et al, 2014), with an additional dilation operation, to take potential advance or errors in the inventory into account. The difference in result for this masking procedure is shown 10 in Figure 7, with some highlights.…”

Spatial-Temporal Characteristics of Glacier Velocity in the Central Karakoram Revealed with 1999–2003 Landsat-7 ETM+ Pan Images

“…Glacier dynamics in the Central Karakoram have a significant influence on the hydrological cycle, especially hydrological planning and water resource management. As one of the crucial factors in mass balance and glacier dynamics [14], the glacier surface velocity provides an indicator of glacier recession or advance/surge [15][16][17] and has been used to interpret glacier dynamics [18]. Therefore, the spatial-temporal characteristics of the glacier velocity in this region are essential to improve our understanding of glacier dynamics and the glacier responses to climate change and influences on regional water sources.…”