Assessing glacier retreat and morphometric change at

Kvíárjökull, Iceland

Georgie BennettMSc by research

Unrealised potential of aerial photography archive

1964 20031945 1964 1980 1998 2003

a) How much ice has been lost between 1945 and 2003?

b) What is the temporal pattern of retreat?

Hypothesis 1Kvíárjökull advanced between 1980 and 1998 in response to increased winter precipitation

Hypothesis 2 Glacier retreat accelerated into the 21st C in response to increased air temperature

Research question 1: What is the nature of glacier retreat:

1945

2003

Research question 2: How is moraine development

‘controlled’ by glacial dynamics:

Hypothesis 3Moraine linearity is inherited from debris bands in the parent ice

Ice marginal pushing?

Transverse margin parallel debris bands

?Process FormForm

Stereophotography 58 year period: 1945, 1964, 1980, 1998, 20039 ground control points (GCPs) on stable points… not ice!!

Methods

1. DEM production and quality assessment Digitally using Leica Photogrammetry Suite 9.1. Accuracy assessed against GCPs

Methods

2. Volume change analysis Sequential DEMs subtracted: volume change maps

Volume change map 1945 – 2003

-

1945

2003

=

Methods3. Surface change analysis

Down glacier profiles New innovative visualization technique: Meshed

temporal profiles4. Error assessment

50 checkpoints extracted from 2003 DEM (RMSE of 0.39) from stable points around the glacier

DEMs compared with 2003 DEM.Vertical accuracy of DEMs compared to GCPs Vertical accuracy compared to 2003

checkpointsYear RMSE Mean error

2003 0.39 0

1998 0.7 0.75

1980 1.38 2.2

1964 1.03 2.36

1945 7.74 -3.11

Results

Total ice loss 1945 - 2003 = 1.8x108 cubic meters from the glacier snout= 75 % of 1945 snout volume

Spatially variable

Research Question 1a:How much volume loss has there been?Volume change map 1945 – 2003

Research Question 1b:What is the temporal pattern of retreat?

Greatest elevation loss from 1998 – 2003

Positive elevation change in 1980 - 1998

Volume change map 1945 – 2003

Red area = ice cored moraine complex has increased in elevation and volume

Ice-marginal pushing

Glacier advance

Volume change map of N snout area 1980 – 1998

1980 – 1998 = increase in volume of glacier snout and ice cored moraine complex

Animation of hillshaded DEMs

1945196419801998200319451964198019982003

4. Ice-cored morainecomplex

-Glacier snout has retreated ~500m and surface has lowered by ~70m -Advance between 1980 and 1998 of ~200m

-Downwasting particularly rapid from 1998- 2003

-Glacier retreat accelerating

2. Glacier snout gradient has downwasted 1. Glacier surface has lowered

3. Deep moulins have developed between 1998 and 2003

Latero-frontal moraine

1945

1964

19801998

2003

Animation of downglacier profiles

4. Ice cored moraine complex has emerged

New innovative visual technique: Meshed temporal profiles

Transect across ice- cored moraine complex

Meshed temporal profile:Large changes in relief across profile between 1945 and 2003

Time

1945

2003

19451964

19801998

2003

Topographic inversion cycles in ice cored moraineSediment redistributed from peaks to troughs

Differential melting of ice coresTopography reversed

1945

1964

1980

1998

2003

Fine linear features destroyed Larger linear features may survive

Evolution of linearity in ice cored moraine

Ice marginal pushing Brings bands of debris to the surface Ice marginal pushing enhances linearity in moraine

Conclusions1. Use of digital photogrammetry has unlocked the

archive of photography enabling quantification of change over a 58 year time period.

Visualization techniques have been invaluable in revealing processes of moraine construction

1964 20031945 1964 1980 1998 2003

Conclusions2. Kvíárjökull retreated between 1945 and 2003

interrupted by an advance between 1980 and 1998

3. Linearity in the outer moraines is the result of a combination of inheritance of former linear debris concentrations in parent ice and ice marginal pushing.

Conclusions

3. 75% of the 1945 snout ice volume was lost by 2003 with the most rapid volume loss occurring between 1998 and 2003.

ICE LOSS IS ACCELERATING

Conclusions

Thank you

Questions?