Assessing spatial change of the Kaskawulsh Glacier using historical and repeat oblique photographs

Date

2021-08-10

Authors

Lang, Kristyn

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Abstract

Glaciers offer scientists valuable insights into past, present, and future climates. However, these insights are currently limited by the time depth from which the record of spatial data exists. Methods to track glacial surface area changes date back to the 1950s using aerial photogrammetric surveys. The use of satellite imagery began with the launch of Landsat 1 in 1972 and has since been the dominant source of data. Canada has the world’s largest historical mountain photograph collection dating back as far as 1888 and holds the potential for nearly a century of additional data through the georectification of historical oblique images. In this study, a systematic review and synthesis of available techniques for photographic (i.e., orthographic and oblique) analysis of glacier surface area was conducted. A trial was then run using custom University of Victoria software, the Image Analysis Toolkit, to ascertain the extent to which oblique photography can be used to assess surface area change of valley glaciers. The surface area of the Kaskawulsh Glacier in view of repeat and historical photographs was quantified in 2012 and 1900, respectively. The result from the modern oblique imagery was compared to the classification of ice derived from satellite optical imagery and revealed that the geolocation of clean and debris covered ice was consistent. The historical oblique imagery showed an increase in debris cover over 112 years, which has implications for the rate of ice melt. Further research and application in glacial studies could increase the temporal coverage of available data for improved climate modelling and foster deeper understandings of the future of Canadian alpine regions.

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Keywords

valley glacier, historical photographs, GIS, satellite imagery, land cover change

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