Annals of Glaciology 50(52) 2009
41
Glacier velocities across the central Karakoram
Luke COPLAND,1 Sierra POPE,1 Michael P. BISHOP,2 John F. SHRODER, Jr,2
Penelope CLENDON,3 Andrew BUSH,4 Ulrich KAMP,5 Yeong Bae SEONG,6
Lewis A. OWEN7
1
Department of Geography, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
E-mail: luke.copland@uottawa.ca
2
Department of Geography and Geology, University of Nebraska at Omaha, Omaha, NE 68182-0199, USA
3
Department of Geography, University of Canterbury, Private Bag 4800, Christchurch, New Zealand
4
Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta T6G 2E3, Canada
5
Department of Geography, University of Montana, Missoula, MT 59812-1018, USA
6
Department of Geography Education, Korea University, Seoul 136-701, Korea
7
Department of Geology, University of Cincinnati, Cincinnati, OH 45221-0013, USA
ABSTRACT. Optical matching of ASTER (Advanced Spaceborne Thermal Emission and Reflection
Radiometer) satellite image pairs is used to determine the surface velocities of major glaciers across the
central Karakoram. The ASTER images were acquired in 2006 and 2007, and cover a 60 120 km region
over Baltoro glacier, Pakistan, and areas to the north and west. The surface velocities were compared
with differential global position system (GPS) data collected on Baltoro glacier in summer 2005. The
ASTER measurements reveal fine details about ice dynamics in this region. For example, glaciers are
found to be active over their termini even where they are very heavily debris-covered. The
characteristics of several surge-type glaciers were measured, with terminus advances of several
hundred meters per year and the displacement of trunk glaciers as surge glaciers pushed into them. This
study is the first synthesis of glacier velocities across this region, and provides a baseline against which
both past and future changes can be compared.
1. INTRODUCTION
2. STUDY AREA AND PREVIOUS MEASUREMENTS
The Karakoram is situated at the western end of the transHimalaya and is one of the largest glaciated areas
outside of the polar regions, with nine glaciers >50 km in
length. Rapid uplift is occurring in this region, with evidence that this is largely driven by rapid surface erosion
caused by processes such as landsliding and fluvial and
glacial action (Burbank and others, 1996; Seong and
others, 2008). Estimated exhumation rates are 3–6 mm a–1
over the past 5 Ma (Foster and others, 1994). However, as
there are currently few direct measurements of surface
processes in this region, it is hard properly to evaluate
their relative importance in driving tectonic uplift. This
study provides the first comprehensive determination of
glacier surface velocities across the entire central Karakoram, a critical first step in the investigation of erosion
rates by glaciers.
The velocities we report were derived for a wide range of
glacier sizes and extents, mainly via optical image
matching of satellite scenes. Clear-sky ASTER (Advanced
Spaceborne Thermal Emission and Reflection Radiometer)
scenes provided the main data source and velocities were
derived for the period between summer 2006 and summer
2007. The image-based velocity calculations were compared with differential global positioning system (GPS)
measurements made in summer 2005 and with data
provided in previously published field reports. Patterns of
spatial variability in measured ice velocities allow for firstorder determination of the importance of basal sliding vs
internal deformation in glacier motion in this region,
knowledge of which is important when quantifying likely
basal erosion rates.
This study focuses on Baltoro glacier, Pakistan, and areas to
the north and west of it, close to the border between Pakistan
and China (Fig. 1). The glaciers in this area are some of the
longest mid-latitude ice masses in the world: Siachen glacier
is 72 km, Hispar glacier is 61 km, Biafo glacier is
60 km, and Baltoro and Batura glaciers are both 58 km
long. These glaciers are located within the central Karakoram, which is the highest, and one of the remotest and
least accessible, mountain ranges on Earth (Searle, 1991). As
such, little is known about many of even the most basic
glaciological processes in this region.
Existing observations of glacier processes in the Karakoram are biased towards areas that are relatively accessible
on the ground, such as traditional trading routes, mountain
passes, and climbing routes towards major peaks such as K2.
Much of the previous glaciological work has focused on the
characteristics of unusual features, such as catastrophic
glacier advances and outburst floods, as well as terminus
advance and retreat patterns (e.g. Hayden, 1907; Mason,
1935; Desio, 1954; Hewitt, 1969; Mayewski and Jeschke,
1979; Goudie and others, 1984). In large part, previous work
was driven by the particularly large concentration of surging
glaciers that occur in the Karakoram (Hewitt, 1969, 1998,
2007, http://www.agu.org/eos_elec/97106e.htm).
Given the interest in surging glaciers in this region, many
measurements of surface motion have been made on such
glaciers. For example, Desio (1954) reported that Kutiûh
glacier moved at a mean speed of 113 m d–1 based on
terminus advance rates during a 3 month surge in 1953.
Gardner and Hewitt (1990) measured mean surface velocities
of 7.59 m d–1 (2.77 km a–1) from a cross-glacier profile during
42
Copland and others: Glacier velocities across the central Karakoram
Fig. 1. Map of study area, with main features and locations labeled. The red box in the main panel indicates outline of ASTER imagery used
in the feature tracking calculations.
a 1986 surge of Bualtar glacier, compared with 146 m a–1
during the previous summer. Although these velocities are
useful in understanding the dynamics of surging glaciers,
extrapolating these findings to the many other glaciers in this
region that do not surge is problematic. In addition, terminus
advance rates do not equate directly to ice-surface velocities
because they are influenced by, among other factors, the
balance between forward ice flow and surface melting.
There have been a few previous measurements of the
surface motion of non-surging glaciers in the Karakoram. The
Batura Glacier Investigation Group (1979) measured velocities across Batura glacier in the mid-1970s and found an
overall average of 100 m a–1, with a general peak at the firn
line and a decrease towards the glacier terminus. Summer
speed-ups were generally <20% of the total annual motion.
Young and Schmok (1989) measured summer motion of 124–
208 m a–1 across a transect on Miar (Barpu) glacier in the
summers of 1986 and 1987. Mayer and others (2006) used
differential GPS to measure 32 stakes across Baltoro glacier in
summer 2004, immediately upstream of our feature-tracking
measurements. They recorded maximum velocities of
214 m a–1 close to the equilibrium line at Concordia, with
velocities around 100 m a–1 across most of the rest of the
glacier. However, Mayer and others (2006) state that
comparisons with velocities that they derived from manual
feature tracking of satellite imagery indicate that mean
annual velocities are approximately half of those measured
by GPS in the summer. They therefore concluded that basal
sliding is the dominant motion mechanism for Baltoro
glacier, at least during the summer melt season.
Within the region covered by this study, the only previous
velocity measurements on a non-surging glacier were made
on Biafo glacier by Hewitt and others (1989), who recorded
summer velocities between 128 and 226 m a–1 close to the
midpoint of the ablation area, although winter velocities
were approximately half those in the summer. Direct
comparison of these velocities with the feature-tracking
results is presented below in section 5.
Examples of recent glaciological applications of the
image-pair correlation method include the studies by
Berthier and others (2005) and Kääb (2005). Berthier and
others (2005) cross-correlated Système Probatoire pour
l‘Observation de la Terre (SPOT)-5 satellite images to
determine the flow of mountain glaciers in the Swiss Alps,
whereas Kääb (2005) used ASTER images to derive alpine
glacier flow velocities in the Bhutan Himalaya. Both groups
found that the feature-tracking method provided a successful
alternative to synthetic aperture radar (SAR) interferometry,
requiring no ground control points and enabling measurement of surface velocities in regions and over periods not
covered by radar satellite missions. In the Himalaya,
Luckman and others (2007) provided one of the most
detailed image correlation studies to date, using satellite
radar feature tracking. Using European Remote-sensing
Satellite (ERS) SAR images, they determined glacier velocities and flow directions in the Everest region, and
concluded that the debris cover of Himalayan glaciers
makes them particularly favorable for feature tracking due to
the surface patterning produced.
3. METHODS
In this study, ice motion was derived from feature tracking
performed on pairs of clear-sky visible satellite images.
These measurements were compared against velocities
recorded from differential GPS measurements where available.
3.1. Field measurements
In summer 2005, GPS measurements of surface motion were
made at six locations on lower Baltoro glacier (Fig. 2).
Locations were marked with a pole drilled into the ice, or
with paint on large boulders, and their position surveyed
with a Trimble R7 differential GPS. Occupation times at
each location were 30 min, and the time between surveys
varied between 14 and 22 days (Table 1). The data were
Copland and others: Glacier velocities across the central Karakoram
43
Fig. 2. Velocity patterns across Baltoro glacier and its northern tributaries derived from feature tracking. Velocity cross-profiles are shown for
locations A–A0 and B–B0 . Numbered points indicate differential GPS measurement locations (Table 1). Arrows indicate location of featuretracking match points, and calculated flow direction. Velocities not shown where <15 m a–1 or where feature tracking was not successful.
differentially corrected using a semi-permanent base station
in Skardu (80 km southwest of Baltoro glacier), temporary
base stations at camp sites off the edges of the glacier, or the
Precise Point Positioning (PPP) solution provided by Natural
Resources Canada (http://www.geod.nrcan.gc.ca/productsproduits/ppp_e.php). Positions are considered accurate to
within 0.05 m horizontally and 0.10 m vertically. Note
that these GPS measurements were collected prior to the
2006–07 period over which the feature-tracking measurements were made. However, they still provide the best
available information concerning summer velocity patterns
in the absence of any coincident field measurements from
the feature-tracking period itself.
3.2. Feature tracking
Surface velocities were derived from pairs of clear-sky
satellite scenes by automated tracking of surface features
such as crevasses and surface debris between scenes. The
feature tracking was undertaken with VisiCORR Windowsbased software (Dowdeswell and Benham, 2003), which is
based on the IMCORR image cross-correlation software
developed by Scambos and others (1992). This method
enables velocities to be determined to the sub-pixel level.
Georectified ASTER L1B scenes were used as input for the
analyses, downloaded from NASA’s Earth Observing System
Data Gateway. These images have a pixel size of 15 m in the
visible and near-infrared bands used, and summer images
Table 1. Comparison between velocities derived from GPS vs feature-tracking (F-T) measurements on Baltoro glacier. All velocities are
standardized to units of m a–1. The F-T velocities (from 2006–07) are provided from the closest match point to the GPS measurements (from
summer 2005), within a maximum of four pixels (60 m) horizontal distance
Point
1
2
3
4
5
6
GPS
latitude
GPS
longitude
GPS
elevation
8
8
m
35.69366
35.72106
35.72472
35.71891
35.73274
35.73558
76.16118
76.23045
76.23064
76.23159
76.28443
76.28507
3483.5
3816.4
3835.2
3810.5
3991.2
3995.8
GPS survey 1
(2005)
25 June
28 June
28 June
28 June
30 June
01 July
GPS survey 2
(2005)
17
16
16
16
15
15
July
July
July
July
July
July
GPS
velocity
GPS
direction
F-T
velocity
F-T
direction
Velocity
difference
m a–1
8
m a–1
8
%
10.3
38.3
44.9
19.7
91.5
117.1
242
242
246
235
252
256
7.6
34.2
46.1
23.5
81.2
86.3
223
236
238
222
253
252
–26.0
–10.7
+2.7
+19.3
–11.3
–26.3
44
were chosen to reduce the presence of snow cover. Images
were also chosen based on their contrast and exposure
quality, cloud cover, and acquisition characteristics; midday
images from near-identical overlapping passes are most
conducive to correlation processing. Ultimately, two pairs of
scenes were used in the analysis: two scenes from adjacent
acquisitions on 26 July 2006 (at 05:52:31 UTC and 05:52:40
UTC), and two scenes from adjacent acquisitions on 27 June
2007 (at 05:52:52 UTC and 05:53:01 UTC). Each scene
covers a ground area of 60 60 km.
Initial processing involved image co-registration, followed by de-rotation of the images in ENVI software and
extraction of band 3N in GeoTIFF format. Selected image
sections, ranging from individual tributaries to full drainage
basins, were then exported as eight-bit grayscale scenes and
processed using VisiCORR. The main user-set parameters in
VisiCORR are the search and reference chip sizes for the
image cross-correlation calculations; after extensive testing,
the optimal sizes were found to be 64 and 32 pixels,
respectively. A grid spacing of eight pixels between adjacent
correlation attempts was found to provide the best balance
between processing speed and accurate velocity determinations. The final results from the feature-tracking calculations
were output as a text file from VisiCORR, corrected to values
of m a–1, imported into ArcGIS software, and plotted on top
of the original ASTER satellite imagery.
An assessment of the errors in the feature-tracking results
was undertaken via an analysis of: (1) internal consistency of
the velocity magnitudes (i.e. velocities should decrease in
speed towards the glacier margins); (2) internal consistency
of the velocity directions (i.e. glaciers should move in a
generally downhill direction); and (3) the apparent movement of non-glaciated areas surrounding the glaciers (i.e.
there should be no apparent motion in these regions). These
checks indicated that the feature-tracking results generally
produced realistic ice-motion patterns, with estimated errors
in the velocity derivations being approximately 1 pixel
between scenes. As the ASTER scenes were acquired around
1 year apart, only ice motion >15 m a–1 is plotted here to
remove any ambiguity in the results. In addition, velocities
are not plotted where matches were not possible or where
there were obvious mismatches that produced anomalously
different velocities (in either magnitude or direction) from
expected and/or from surrounding points.
3.3. Determination of ice-motion mechanisms
The relative importance of basal sliding vs internal deformation in accounting for observed surface motion can be
determined from the spatial variability in velocities across
transverse profiles. In areas where basal sliding dominates,
ice tends to move en masse, with high but relatively constant
velocities in the glacier center and rapid reductions close to
the margins. This has been termed blockschollen (or plug
flow) motion by some, particularly in relation to Karakoram
glaciers (e.g. Finsterwalder, 1937; Kick, 1962), and is
believed to represent a slab-like movement. By contrast,
velocities that are generally low and increase gradually from
the edges to the center of a glacier in a parabolic pattern are
more likely to represent motion dominated by internal ice
deformation. The surge of Variegated Glacier, Alaska, USA,
provides an excellent example of the contrast between these
motion types. Pre- and post-surge velocities are relatively
low (0.10–0.20 m d–1) and have a parabolic profile during
periods dominated by deformational flow, whereas profiles
Copland and others: Glacier velocities across the central Karakoram
at the same location during surges show high and constant
motion (2.5–13 m d–1) across almost the entire glacier
when basal sliding is dominant (Kamb and others, 1985,
their fig. 7). Transverse profiles have been used to infer the
importance of basal sliding vs internal deformation from
remote-sensing measurements on other glaciers (e.g. Fatland
and others, 2003), and here we use them to make a general
assessment of their relative importance on central Karakoram glaciers.
4. RESULTS AND DISCUSSION
Image matching was undertaken for the entire region
covered by the ASTER satellite scenes, with good results
produced for the ablation areas of all the major glaciers. The
discussion here focuses first on the characteristics of
individual drainage basins and glaciers, before presenting
a regional synthesis.
4.1. Baltoro glacier
The ASTER imagery covered the lowermost 13 km of Baltoro
glacier and associated tributaries. These areas tend to be
heavily covered in debris, and their distinctive surface
patterning makes them ideal for image matching. The
velocity directions show fine details as the tributary glaciers
round corners to join the main Baltoro glacier, and as the ice
is channeled by the surrounding topography (Fig. 2). There is
a general decrease in velocity towards the margins and
termini of the glaciers, with the highest velocities reaching
>200 m a–1 on icefalls in the upper parts of Uli Biaho and
Trango glaciers. Velocities on the main Baltoro glacier
average 50 m a–1, ranging from 75 m a–1 in the upper part
of the study area to <15 m a–1 within the lowermost 2–3 km
of the glacier.
As a check on the accuracy on the feature-tracking
results, comparisons are made with the GPS-derived velocities from summer 2005 (Table 1; Fig. 2). In general, there
is a close correspondence between the velocities measured
at the six GPS locations and the feature-tracking results,
particularly in relation to direction, with <5% variation in
measured direction between the two methods. There is
greater variability in the magnitudes of the velocities, these
being on average higher in the GPS measurements than in
the feature-tracking results. However, most of the recorded
differences are within the estimated feature-tracking error
limits of 15 m a–1. The only exception is point 6, which
was significantly faster in the GPS measurements. Mayer and
others (2006) also recorded GPS (summer) velocities that
were greater than the annual average derived from manual
feature tracking on Baltoro glacier; summer motion was up
to 100% higher than winter motion in the upper parts of the
ablation area (above the region shown in Fig. 2). We did not
see such dramatic summer increases in velocity in this study,
however, probably because the position of the highestelevation GPS points in this study (5 and 6) is where the
lowest-elevation GPS points started in the study undertaken
by Mayer and others (2006).
These results indicate that Baltoro glacier experiences
spatial and temporal variations in ice motion, but that these
variations are not necessarily synchronous across the glacier.
Higher summer velocities are commonly observed on
temperate and polythermal glaciers, and are usually
attributed to basal lubrication caused by subglacial water
flow (Paterson, 1994). This seems likely at Baltoro glacier, as
Copland and others: Glacier velocities across the central Karakoram
45
Fig. 3. (a) Velocity patterns across South Skamri and Skamri glaciers derived from feature tracking (current boundary between glaciers
marked with red line). Inset shows velocity long-profile marked by white line. Arrows indicate location of feature-tracking match points and
calculated flow direction. Velocities not shown where <15 m a–1 or where feature tracking was not successful. (b) Landsat image (18 July
1978) of the same region. (c) ASTER image (27 June 2007) used in (a), but without superimposed velocities.
there are many moulins and crevasses across the ablation
area where meltwater can reach the glacier interior and bed,
and surface melting is widespread in the summer. In summer
2005, for example, surface melt rates of 6.5 cm d–1 were
recorded close to GPS point 4, and 5.9 cm d–1 2 km
upstream of GPS point 6. The cross-profile B–B0 shows a
rapid increase in velocity away from both margins, which
suggests that basal sliding is the dominant motion mechanism in this part of the glacier (Fig. 2). Profile A–A0 shows
quite a different pattern, however, with a more parabolic
shape as velocities gradually rise to a peak in the center of
the glacier (Fig. 2). This suggests that ice deformation is a
more dominant motion mechanism close to the terminus,
although basal sliding could still be important in the center
of the glacier where subglacial water flow would presumably concentrate and increase basal lubrication. The very
low velocities close to the margin at location A probably
represent the influence of Trango glacier entering the main
valley and slowing the ice immediately upstream. The
greater importance of internal deformation towards the
glacier terminus ties in with the GPS observations (described
above) that significant increases in summer motion only
occur in the upper part of our study area, and in the regions
above it recorded by Mayer and others (2006).
Overall, the GPS observations indicate that the featuretracking results provide a realistic estimate of annual
velocity patterns, both in terms of direction and magnitude.
This gives confidence in the application of the technique to
the other glaciers in this region.
4.2. South Skamri glacier
South Skamri glacier is located 30 km north of the Baltoro
glacier drainage basin. It is a tributary of Skamri (Yengisogat)
glacier (Fig. 3a). Historical Landsat imagery indicates a
complex flow history between these glaciers. In 1978, the
distortion of surface moraines suggests that Skamri glacier
was surging, or had recently surged, and that it was the
dominant flow unit in the basin (Fig. 3b). At this time, it
46
pushed aside most of South Skamri glacier, effectively
cutting it off from its lower terminus.
By 2007, it had become clear that South Skamri glacier
has surged, pushing Skamri glacier aside and now making
South Skamri the dominant ice-flow unit in the basin
(Fig. 3c). The feature-tracking results indicate that South
Skamri glacier was active throughout its ablation area at this
time, with velocities >250 m a–1 over an icefall in the upper
part of its ablation area (Fig. 3a). The entire lower glacier is
heavily debris-covered, with the velocities gradually decreasing in an along-glacier direction and towards the
margins. In general, there are high and constant velocities
over most of the upper ablation area where the ice flow is
channelized, with a rapid reduction in flow (from >200 m a–1
to <100 m a–1 over a horizontal distance of 1 km) as the ice
exits the main channel and spreads out over the wider lower
valley (Fig. 3a inset).
An interesting feature of the velocity patterns shown in
Figure 3a is that the boundary between South Skamri and
Skamri glaciers occurs several kilometers upstream of the
current end of the actively flowing ice (>15 m a–1). The
velocity magnitudes and directions suggest that ice input
from South Skamri glacier is now causing Skamri glacier to
move downstream of where the glaciers join, as there is little
evidence for current inputs from the main Skamri valley.
When comparison is made with earlier imagery, it is clear
that Skamri glacier provided the main driver of ice flow over
much of the terminus prior to 1978 (Fig. 3b), but that the
main flow driver has now switched to South Skamri glacier.
Beyond the currently active ice shown in Figure 3a is a large
area of stagnant ice at the glacier snout. This was derived
originally from South Skamri glacier, but was effectively cut
off by the 1978 (or earlier) surge of Skamri glacier.
In terms of the dominant ice-motion mechanism, the
rapid increase in velocities away from the glacier margins
and towards the glacier center in the upper part of South
Skamri glacier is suggestive of basal sliding in this area. By
contrast, the gradual reduction in velocities across the lower
ablation area is more suggestive of deformation flow. This
ties in with the large, dead ice areas in front of the existing
active ice front, which are currently receiving insufficient
mass to drive ice flow in that area.
4.3. Choktoi/Panmah glacier
Choktoi glacier forms the upper part of Panmah glacier, and
their combined ablation area extends 20 km (Fig. 4a). The
ice velocities derived from feature tracking along Choktoi
glacier average 100 m a–1 over the central part of the
ablation area, with a gradual decrease to zero over the
lowermost 8 km where it forms Panmah glacier (Fig. 4a
inset). Velocity estimates for the upper 5 km of the D–D0
profile shown in Figure 4a have a high degree of uncertainty
due to the limited number of match points over this region,
with the dotted purple line providing a best estimate of
velocities over this area. The overall average velocity for the
18 km profile shown in Figure 4a is 80 m a–1, which suggests
an average residence time of 225 years for the ice passing
through the ablation area of the Choktoi/Panmah basin. Ice
velocities increase rapidly away from the margins across the
central part of Choktoi glacier, which suggests that basal
sliding (blockschollen) is the dominant motion mechanism
for this basin.
Nobande Sobonde glacier, to the north of Panmah glacier,
is largely inactive over the area shown in Figure 4a, except
Copland and others: Glacier velocities across the central Karakoram
where tributaries join the main trunk. As discussed by
Hewitt (2007), all of these tributaries have surged in the
recent past. Chiring glacier surged in 1995, whereas the
adjacent South Chiring (Maedan) glacier surged sometime
between 2002 and 2005. South Chiring glacier still eclipses
the flow from Chiring glacier, with measured velocities of up
to 60 m a–1 over its terminus region. However, velocities
could not be derived for the upper ablation areas of Chiring,
South Chiring and Second Feriole glaciers due to the low
surface debris cover and few crevasses in these regions that
precluded the finding of feature-tracking match points.
Second Feriole (Shingchukpi) glacier started surging in
the fall or winter of 2004/05, and the velocity vectors in
Figure 4a indicate that this surge pushed the ice of Nobande
Sobonde glacier to the side (as also discussed by Hewitt,
2007). The measured velocities on Second Feriole glacier
are very similar to those on South Chiring glacier, suggesting
that the surging had probably stopped by 2006–07.
Unlike the relatively low velocities measured for the
tributaries discussed above, the Drenmang and First Feriole
glaciers showed very high local velocities of >200 m a–1 at
their termini over 2006/07. Hewitt (2007) states that
Drenmang glacier probably started surging in fall or winter
2004/05, with the glacier in summer 2005 overriding lateral
moraines that had been ice-free for decades. Prior to this,
Drenmang glacier last surged in 1977–78, with imagery
from 1993 suggesting that the terminus moved at an average
rate of 500 m a–1 in the 15 years after this event (Hewitt,
2007). From the velocity patterns shown in Figure 4a it is
clear that the current terminus is very active, with Figure 4d
and e showing the advance of Drenmang glacier between
summer 2006 and 2007. Distortion and folding of the
medial moraines is also evident in these images, which
provide further evidence of recent surging. Hewitt (2007)
argues that the 2004–05 surge probably started in the
eastern branch, and today it is this tributary that dominates
flow out of the basin, with the terminus pushing into the
main trunk of Nobande Sobonde glacier and constructing its
flow (Fig. 4d and e). One important distinction to make is
whether the 2006–07 feature-tracking velocities are indicative of a continuing surge of Drenmang glacier that started in
2004–05, or whether they represent a post-surge relaxation
phase of enhanced velocities. The latter explanation seems
more likely, as actual Karakoram surges typically last for
only a few weeks to months (e.g. 3 months for a 12 km surge
of Kutiah glacier (Desio, 1954); 8 days for a 3.2 km surge of
Yengutz glacier; and 2.5 months for a 9.7 km surge of
Hassanabad glacier (Hayden, 1907)). Furthermore, Hewitt
(2007) states that it can take glaciers many years to return to
pre-surge conditions after a surge has occurred. Moreover,
the terminus velocities of 250 m a–1 are in the range likely
for a post-surge slowdown, rather than full surge conditions.
Although a surge has not previously been recorded for
First Feriole glacier, from visual inspection of the ASTER
scenes (Fig. 4b and c), and from the high near-terminus
velocities recorded by the feature tracking (Fig. 4a), it is clear
that the glacier is currently very active. The terminus
advanced 250 m over the 2006–07 measurement period,
was very steep and bulbous, and the ablation area appears
to have thickened during this time (Fig. 4b and c). As
discussed above, the three glaciers immediately to the north
of First Feriole glacier all surged in the previous decade or so
(Hewitt, 2007), and old Landsat imagery (not shown)
indicates that the glacier terminus was 3 km advanced
Copland and others: Glacier velocities across the central Karakoram
47
Fig. 4. (a) Velocity patterns across the Panmah glacier region derived from feature tracking. Arrows indicate calculated flow direction and are
spaced every 25 pixels. Inset shows velocity long-profile marked by D–D0, with dotted purple line indicating average velocity over upper
5 km where fewer feature-tracking match points were found. Velocities not shown where <15 m a–1 or where feature tracking was not
successful. (b, c) Advance of First Feriole glacier, 2006–07. (d, e) Advance of Drenmang glacier, 2006–07.
from its present position in 1978 when surrounding glaciers
were all retreating. These disparate sources of evidence all
point to the fact that First Feriole glacier is likely to be a
surge-type glacier, although we cannot discern whether the
full surge process, or just a portion of it, was captured by the
2006–07 imagery.
5. OVERVIEW AND CONCLUSIONS
The feature-tracking calculations discussed here have enabled the production of the first regional map of glacier
velocities across the central Karakoram (Fig. 5). It is clear that
all of the glaciers in this region are active, even over their
terminus regions where there are substantial supraglacial
debris thicknesses (often >1 m). The rapid increase in velocity
away from the margins towards the center of many of the
glaciers suggests that basal sliding is a dominant motion
mechanism, particularly in the middle and upper ablation
areas. Further evidence for this is provided by seasonal
variations in velocity recorded by GPS measurements from
Baltoro glacier, discussed both here and by Mayer and others
(2006). A study by Kääb (2005) in the Bhutan Himalaya
indicated that large differences in dynamics were present
between fast-moving north-facing glaciers and slow-moving
south-facing glaciers, yet there is little evidence for a similar
pattern across the central Karakoram. Instead, velocities
appear to be more influenced by local conditions, with high
velocities where there are icefalls, glacier surges and large
glaciers. Velocities are lower towards glacier termini (where
deformational flow appears to dominate), as well as in
locations where ice input has been constrained or cut off by
the inflow of tributaries or past surges.
Previous velocity measurements on Biafo glacier (Hewitt
and others, 1989) can be used as a check on the featuretracking velocity measurements. Although these were made
over 20 years ago, they provide the only known annual
48
Copland and others: Glacier velocities across the central Karakoram
Fig. 5. Overview of glacier velocities across the central Karakoram derived from feature tracking of ASTER satellite scenes from 26 July 2006
and 27 June 2007 (corrected to values of m a–1). Velocities not shown where <15 m a–1 or where feature tracking was not successful. The red
star on Biafo glacier indicates approximate location of previous velocity measurements made by Hewitt and others (1989).
motion measurements within the current study area. At two
points on a transverse profile, Hewitt and others (1989)
recorded motion of 0.50 and 0.56 m d–1 between 20 July and
12 August 1985; 0.22 and 0.30 m d–1 between 12 August
1985 and 29 May 1986; and 0.63 and 0.60 m d–1 between
29 May and 30 July 1986 (Fig. 5). These equate to velocities
of 108 m a–1 for the point closer to the glacier margin and
131 m a–1 for the point closer to the glacier center. These
compare to velocities of 111 and 145 m a–1, respectively,
calculated from the average of six feature-tracking points
nearest to the locations provided by the map of Hewitt and
others (1989). These are both within the stated 15 m a–1 error
for the feature-tracking method, and suggest that the flow of
Biafo glacier has changed little over the last 20 years. This
is supported by field measurements made by the current
authors in summer 2005, which indicated that the terminus
of Biafo glacier was in the same location, or even slightly
advanced, relative to the 1985 position plotted by Hewitt
and others (1989).
The results presented here indicate that optical image
matching of satellite scenes can allow for regional monitoring of glacier dynamics across remote mountain ranges in
the Himalaya, which are difficult to access on the ground.
The technique is applicable across all glaciers up to their
equilibrium lines, which covers a substantial proportion of
ice in this region due to the relatively confined accumulation areas of many of the larger Karakoram glaciers, in
contrast to their extensive ablation regions. This builds on
the work of Kääb (2005) and Luckman and others (2007),
and provides information required for applications such as
Copland and others: Glacier velocities across the central Karakoram
quantifying water resources and surface denudation rates. In
addition, satellite-derived velocity determinations can improve understanding of the dynamics of glacier surging, as
well as aid in the identification of new surges. The primary
limitation of the optical image-matching method is that it
requires distinctive surface patterning for the correlations to
work. This means that velocities cannot be determined for
the accumulation areas of most glaciers due to their snow
cover. However, the extensive surface debris cover of the
lower parts of most Himalayan glaciers means that these
areas are ideal locations for feature tracking.
ACKNOWLEDGEMENTS
We gratefully acknowledge the K2 2005 medical team,
Nazir Sabir Expeditions, and our dedicated porters and
guides for assistance in the field. Access to VisiCORR
software was kindly provided by T. Benham. ASTER data
courtesy of the NASA Jet Propulsion Laboratory, NASA and
Global Land Ice Measurements from Space, with assistance
from J. Kargel. Funding was provided by the US National
Science Foundation (grant BCS-0242339), the US National
Geographic Society, NASA (grant NNG04GL84G), the
Natural Sciences and Engineering Research Council of
Canada, the Canadian Foundation for Innovation, the
Ontario Research Fund and the University of Ottawa.
Comments from two anonymous reviewers are appreciated
and significantly improved the manuscript.
REFERENCES
Batura Glacier Investigation Group. 1979. The Batura Glacier in
the Karakoram mountains and its variations. Sci. Sin., 22(8),
958–974.
Berthier, E. and 7 others. 2005. Surface motion of mountain glaciers
derived from satellite optical imagery. Remote Sens. Environ.,
95(1), 14–28.
Burbank, D.W. and 6 others. 1996. Bedrock incision, rock uplift
and threshold hillslopes in the north-western Himalayas. Nature,
379(6565), 505–510.
Desio, A. 1954. An exceptional advance in the Karakoram-Ladakh
region. J. Glaciol., 2(16), 383–385.
Dowdeswell, J.A. and T.J. Benham. 2003. A surge of Perseibreen,
Svalbard, examined using aerial photography and ASTER highresolution satellite imagery. Polar Res., 22(2), 373–383.
Fatland, D.R., C.S. Lingle and M. Truffer. 2003. A surface motion
survey of Black Rapids Glacier, Alaska, U.S.A. Ann. Glaciol., 36,
29–36.
Finsterwalder, R. 1937. Die Gletscher des Nanga Parbat, Glaziologische Arbeiten der Deutschen Himalaya-Expedition 1934
und ihre Ergebnisse. Z. Gletscherkd., 25, 57–108.
Foster, D.A., A.J.W. Gleadow and G. Mortimer. 1994. Rapid
Pliocene exhumation in the Karakoram (Pakistan), revealed by
View publication stats
49
fission-track thermochronology of the K2 gneiss. Geology, 22(1),
19–22.
Gardner, J.S. and K. Hewitt. 1990. A surge of Bualtar Glacier,
Karakorum Range, Pakistan: a possible landslide trigger.
J. Glaciol., 36(123), 159–162.
Goudie, A.S., D.K.C. Jones and D. Brunsden. 1984. Recent
fluctuations in some glaciers of the Western Karakoram
mountains, Hunza, Pakistan. In Miller, K.J., ed. The International
Karakoram Project, Vol. 2. Cambridge, etc., Cambridge University Press, 411–455.
Hayden, H.H. 1907. Notes on certain glaciers in north-west
Kashmir. Rec. Geol. Surv. India, 35(3), 127–137.
Hewitt, K. 1969. Glacier surges in the Karakoram Himalaya
(Central Asia). Can. J. Earth Sci., 6(4, Part 2), 1009–1018.
Hewitt, K. 1998. Glaciers receive a surge of attention in the
Karakoram Himalaya. Eos, 79(8), 104–105.
Hewitt, K. 2007. Tributary glacier surges: an exceptional concentration at Panmah Glacier, Karakoram Himalaya. J. Glaciol.,
53(181), 181–188.
Hewitt, K., C.P. Wake, G.J. Young and C. David. 1989. Hydrological investigations at Biafo Glacier, Karakorum Range,
Himalaya; an important source of water for the Indus River.
Ann. Glaciol., 13, 103–108.
Kääb, A. 2005. Combination of SRTM3 and repeat ASTER data for
deriving alpine glacier flow velocities in the Bhutan Himalaya.
Remote Sens. Environ., 94(4), 463–474.
Kick, W. 1962. Variations of some central Asiatic glaciers. IASH
Publ. 58 (Symposium at Obergurgl 1962 – Variations of the
Regime of Existing Glaciers), 223–229.
Luckman, A., D.J. Quincey and S. Bevan. 2007. The potential of
satellite radar interferometry and feature tracking for monitoring
flow rates of Himalayan glaciers. Remote Sens. Environ.,
111(2–3), 172.
Mason, K. 1935. The study of threatening glaciers. Geogr. J., 85(1),
24–41.
Mayer, C., A. Lambrecht, M. Belò, C. Smiraglia and G. Diolaiuti.
2006. Glaciological characteristics of the ablation zone of
Baltoro glacier, Karakorum, Pakistan. Ann. Glaciol., 43, 123–131.
Mayewski, P.A. and P.A. Jeschke. 1979. Himalayan and transHimalayan glacier fluctuations since A.D. 1812. Arct. Alp. Res.,
11(3), 267–287.
Raymond, C.F. and 7 others. 1985. Glacier surge mechanism:
1982–1983 surge of Variegated Glacier, Alaska. Science,
227(4686), 469–479.
Scambos, T.A., M.J. Dutkiewicz, J.C. Wilson and R.A. Bindschadler.
1992. Application of image cross-correlation to the measurement of glacier velocity using satellite image data. Remote Sens.
Environ., 42(3), 177–186.
Searle, M.P. 1991. Geology and tectonics of the Karakoram
mountains. Chichester, Wiley.
Seong, Y.B. and 8 others. 2008. Rates of bedrock incision within an
actively uplifting orogen: Central Karakoram Mountains, Pakistan. Geomorphology, 97(3–4), 274–286.
Young, G.J. and J.P. Schmok. 1989. Ice loss in the ablation area of a
Himalayan glacier; studies on Miar Glacier, Karakorum Mountains, Pakistan. Ann. Glaciol., 13, 289–293.