Reconstructing morphometric change in a proglacial landscape using historical aerial photography and automated DEM generation

This paper explores the feasibility of using historical aerial photographs and digital photogrammetric procedures to reconstruct morphometric landscape changes in a proglacial setting of the southern Coast Mountains, British Columbia, Canada. The photographic record includes 12 sets of vertical photography, obtained at a range of large to medium nominal scales, for the period 1947 to 1997. An automated procedure of digital elevation model (DEM) extraction was employed and details of morphometric change were assessed by differencing the DEM surfaces obtained for different dates of photography. Results are used to describe terrain surface changes associated with glacier recession, moraine gully erosion, and forest growth in the glacial forefield. Methods are reviewed for the estimation and handling of systematic and random vertical errors in the DEMs that are suitable for this type of environment, where there are no historical surveys or monuments to use as a common benchmark and only natural features are available for establishing ground control. Digital photogrammetry, applied to scanned archived photography, can be used to generate high-resolution (sub-meter) DEM surfaces of proglacial terrain suitable for quantifying decadal-scale morphometric changes that have occurred since the mid-20th century to recent times. Potential applications of these techniques and the associated historical data are discussed.