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Title: Changes in volume and extent of NW Svalbard glaciers using airborne lidar and digital photogrammetry
Author: Barrand, Nicholas Edward
Awarding Body: Swansea University
Current Institution: Swansea University
Date of Award: 2007
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Monitoring fluctuations in the mass of the Earth's ice-sheets, ice-caps and glaciers is of fundamental societal importance due to their direct and measurable effects on global sea-levels. Uncertainty in the sea-level rise contribution from small glaciers and ice-sheets exists in part due to problems of sample size, distribution and scaling of long-term mass balance measurements. Photogrammetric processing of aerial photography archives offers the opportunity to reconstruct historical mass changes for regions where no such data are available. The ability to derive DEM measurements of glacier volume from photogrammetry is dependent on image texture for surface-matching and good quality, well-distributed ground reference data, which are often difficult to acquire. The aim of this research was to examine the quality (vertical elevation accuracy) of airborne laser scanning (lidar) data in order to utilise raw point data as ground control in historical photogrammetric models. This technique was then used to measure volume changes at NW Svalbard glaciers, thus circumventing the need to measure control in the field. Precision and accuracy of lidar data were found to vary both within and between the lidar swaths, and large numbers of raw lidar points were successfully used to control photogrammetric models. DEMs produced using lidar-derived points were optimised to produce volume change measurements comparable to those from lidar-lidar model differencing. Poorly controlled photogrammetry was shown to overestimate changes in glacier volume by as much as 50%. Two glaciers in NW Svalbard were shown to be losing mass at an accelerating rate, since 1966 and 1990 respectively, in response in increases in average summer air temperatures. Average present-day mass loss was greater than previously estimated, suggesting an increased contribution to sea-level rise from Svalbard glaciers. This method provides a powerful tool for exploiting image archives and may be used in the future to generate high-quality measurements of glacier mass balance.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available