Science Service System

Summary of Proposal GEO1546

TitleQuantifying the flow of Karakoram glaciers
Investigator Quincey, Duncan - University of Leeds, School of Geography
Team Member
Dr Luckman, Adrian - Swansea University, Department of Geography
SummaryThe primary aim of this project is to quantify recent changes in the surface dynamics of glaciers in the Karakoram region of Pakistan. Recent high-impact publications (Scherler et al., 2011; Berthier et al., 2012; Bolch et al., 2012) have highlighted that many Karakoram glaciers have advanced and thickened in recent years in response to local increases in winter precipitation. Other work (Quincey et al., 2011) has highlighted that some Karakoram glaciers have advanced periodically during surges, when velocities increase rapidly to rates between one and two orders of magnitude greater than during quiescence. Sudden changes in glacier flow have significant impact on landscape evolution, with short, intense periods of glacier erosion and sediment transport interspersed with longer periods of relative stability. They also impact on local populations, who frequently harvest glacier meltwater for sanitation and drinking purposes, and can be the source of outburst floods, often associated with the termination of surge events and the blockage of main rivers by advancing glacier ice. Yet still relatively little is known about the factors controlling glacier flow in the region, or the rapidity with which the glaciers may respond to climatic changes. The relatively small amount of data relating to Karakoram surges suggests that they are controlled by basal thermal rather than hydrological conditions, coinciding with high-altitude warming from long-term precipitation and accumulation patterns (Quincey et al., 2011), although other studies have invoked a change in hydrological conditions as the main trigger mechanism in the region (Mayer et al., 2011). Studies in Svalbard and Alaska have demonstrated that the dynamic evolution of the surge can be a strong indicator of the dominant controlling mechanism however, with thermal and hydrological surges characterised by different seasons of initiation, rapidity of onset, and longevity of accelerated flow. Surface velocity data from before, during and after surges, can therefore be extremely useful in understanding the controlling parameters of surging in the region. The objectives of the investigation are thus as follows: 1. To derive surface velocity fields for Karakoram glaciers, both surge- and non-surge type. 2. To characterise Karakoram glacier surges in relation to their dynamic evolution. Methods: Multi-temporal velocity fields will be extracted using cross-correlation feature tracking. Our research on Karakoram glaciers thus far has shown that this technique enables velocities to be quantified over two-weekly, monthly and annual time periods using time-series of Envisat ASAR, ALOS PALSAR, Landsat and SPOT data. The use of TerraSAR-X data will provide a much finer spatial resolution with which we can study the spatial and temporal changes in flow over seasonal time-periods and through the onset of a surge event. We have already identified at least two glaciers that surged during the period of the TSX archive available through this AO and anticipate identifying further flow instabilities through the derivation of surface displacements over other glaciers. To sufficiently sample the temporal evolution of changes in flow we require sequences of Stripmap-mode imagery for each glacier, and therefore request access to ~50 images. The key deliverable from this project will be multiple surface velocity fields characterising glacier dynamics in the Karakoram. In particular, surge velocity data are extremely limited in all glacierised regions of the world, so these velocity fields will provide an unprecedented insight into surging glacier evolution. Results will be published in appropriate high-impact journals (JGR, Global and Planetary Change) and presented at international conferences. Funding for this work is provided by our respective institutions (Leeds and Swansea Universities).

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