Glacial Velocity Changes of Batura Glacier, Western Karakoram Himalaya
Jordan R. Mertes, Michael P. Bishop, John F. Shroder, Jr, Umesh K. Haritashya, Henry N. Bulley, Jeffrey A. Olsenholler
Department of Geography and Geology, University of Nebraska at Omaha. E-mail: Jordanmertes@hotmail.com
METHODOLOGY
ABSTRACT
Glaciers respond directly and indirectly to climate change. Many glaciers around the world are retreating and downwasting, thereby increasing glacial meltwater, as well as debris cover. These variations can cause variations in glacier-flow dynamics including changes in ice velocity and surging.
Our objective was to evaluate ice-flow velocity variations on the Batura Glacier in the western Karakoram Himalaya by combining historical data and diagrams from the Chinese Batura Investigation
Group of the early 1970s with information gathered from satellite image analysis (ASTER 29/
Oct/2003, 13/Sep/2004). Modern ice-flow velocity estimates were generated utilizing ortho-rectified
satellite imagery and feature tracking to produce an ice-flow velocity field. Feature tracking was accomplished using scale-dependent analysis of the NIR band. We generated an average velocity gradient for the Chinese data (12m/yr/100m) and satellite-derived data (23m/yr/100m) using regression
analysis. The Chinese mapping of Batura Glacier delineated the end of the lowermost (south-side)
white ice stream at ~3.2 km from the Karakoram Highway in 1975. Due to down wasting and increasing supraglacial debris cover the white ice stream has retreated up-ice to ~5.9 km as of 2004. Comparison with historical data shows a possible increase in the annual-velocity gradient yet a decrease in
the overall-velocity magnitude. Changes in meltwater at the base from warmer temperatures, or increased mass flux from increased precipitation at altitude, could both change the velocity gradient but
not decrease the overall velocities. Downwasting and thinning ice could explain overall decrease in
velocities and increased debris loads although attendant frictional increases on sides and base might
have some influence.
-Applying various techniques using ARCGIS we were able to take data from the
Batura Glacier Investigation Group (1974) and register it with satellite imagery.
Hand drawn diagrams were registered using ground control points along the lateral moraines of the glacier. The data points from the 1974 diagram are plotted in
Figure 4.
-Human interpretation was used to match points in two images roughly 1 year
apart. This proved to be difficult as reflectance variations were relatively high in
the multitemporal imagery. We managed to obtain approximately 15 points in
order to estimate ice velocity and direction.
Figure 1. Overlay of 1974-1975 Chinese Batura velocity data for the terminus region. Arrows represent actual Chinese data points while the color-map is a interpolation of the velocity field done using ARCGIS.
Figure 2. Overlay of 2003-2004 GLIMS Batura velocity data for the terminus region. Arrows represent velocity point data calculated using newly developed program.
CONCLUSIONS
STUDY AREA
Aerial view to the W/NW of the Batura
Muztagh using ARCGlobe with ASTER
image draped over DEM. Pink outline
encloses the Batura glacier as determined by GLIMS. Overlay of 2003 velocity at the terminus region. Batura is
one of the worlds largest midlatitude
mountain glaciers outside of the polar
regions.
-We also developed a new automated feature tracking program. This program is
based upon scale-dependent analysis of multitemporal satellite imagery. The program uses correlation analysis of unique spatial information to estimate the flow
velocity and direction at the sub-pixel scale. This approach eliminates the need
for preprocessing of imagery in order to obtain good correlation results. It outputs
diagnostic information to permit post processing.
Figure 3. Enlarged view of terminus region of Batura showing what may be a new terminus boundary. The smaller inset image is from Google Earth (April 2007) showing the
current ice cliff located at ice cliff (a).
Figure 4. Original hand drawn diagram of Batura velocities from the Chinese 1974 Batura
Glacier Investigation Group. The diagram was rectified to fit the image used in this study
and individual data points were plotted.
1. Velocity variations from 1974 to 2003 indicate a decrease in the magnitude of
velocity over much of the terminus region of the Batura Glacier. This could be
due to glacier downwasting.
2. The general lowering in magnitude, however, is not uniform, resulting in
higher velocities in the central and upper portions of the glacier. This generates
an increased altitudinal velocity gradient, compared to the gradient in 1974.
This result could be explained by positive mass balance conditions and increased ablation and downwasting in the lower terminus region. Climate reanalysis results for the region support the interpretation of positive mass balance, with precipitation increasing since the 1960’s.
3.The automated program is capable of performing relative co-registration of
multitemporal imagery to reduce error in generating ice velocity estimates.
REFERENCES
1.Batura Glacier Investigation Group (BGIG). 1980. Professional papers on the
Batura Glacier, Karakorum Mountains. Science Press. Beijing (in Chinese with
English abstracts), 1-271.
2.Shroder, J.F., R. Johnson, M. Saqib Khan, M. Spencer. 1984. Batura Glacier
Terminus, 1984, Karakorum Himalaya, Geol. Bull. Univ. Peshawar, 17, 119126.
AKNOWLEGEMENTS
Figure 5. 1974 Chinese velocity data, interpolated and shown Figure 6. Difference of velocities from 1974 to 2003 as deter- Figure 7. 2003 GLIMS velocity data, interpolated and shown
mined through our program and historical data. The lighter ar- with overlain 20m interval contour lines. Note the general
with 20m interval contour lines.
eas show regions of velocity increase whereas the darker areas agreement between data and the current model of glacial flow.
show decreases in velocity.
1. This research is part of the Global Land Ice Measurements From Space Project. This work was funded by the National Aeronautics and Space Administration (Grant NNG04GL84G) .