AN EVALUATION OF SRTM DIGITAL ELEVATION DATA FOR GLACIAL LANDFORM MAPPING IN NEWFOUNDLAND, CANADA

The availability of Shuttle Radar Topography Mission (SRTM) digital elevation models (DEMs) has the potential to revolutionize glacial landform mapping and eliminate many of the shortcomings of more traditional methods, such as aerial photograph interpretation. Although widely used, there has been limited testing of the suitability of SRTM data for such an application. This presentation describes a comparative study of glacial landform mapping from northeast Newfoundland, Canada, using aerial photographs and SRTM DEMs. It forms part of a larger study aimed at identifying sectors of fast flow (ice streams) within the former Newfoundland Ice Cap from their geomorphic footprint.

The study assessed the amount and type of overlap between derived landform data and explored systematic mapping biases that may negatively affect data quality. Results indicated that interpretation from 1:50,000 aerial photographs produced the most detailed landform maps. This was likely the result of large differences in horizontal resolution between mapping sources (≤10 m for aerial photographs and 90 m for SRTM DEMs). The SRTM data permitted identification of larger-scale landforms, particularly ribbed moraine, which were only selectively recorded on aerial photographs. Analysis of landform distribution and surficial geology provided similar results for the two datasets: mapped landform concentrations were highest in areas of thick till and lower in till veneer and bedrock. SRTM DEMs were successful in the identification of regional ice-flow trends and landform patterns. The use of multiple illumination angles avoided biasing in the mapping of linear features in SRTM DEMs, while the integration of supplemental data, such as bedrock and surficial geology, improved overall mapping quality, particularly for flow parallel landforms. Although lacking the finer detail of aerial photographs, the efficiencies offered by SRTM DEMs for reconnaissance mapping of glacial landforms are confirmed.