Using multi-beam RADARSAT-1 imagery to augment mapping surficial geology in northwest Alberta, Canada

Abstract

This paper evaluates the applicability of multi-beam RADARSAT-1 satellite imagery for mapping surficial sediments in northwest Alberta, Canada, using simple arithmetic algorithms. The goal is to make the RADARSAT-1 imagery acquired by the Alberta Geological Survey (AGS) usable to common users who have no access to complex image classification software and (or) expertise. Unlike the Canadian Shield, northern Alberta is mantled with much thicker glacial deposits that are covered by the Northern Boreal Forest. This limits the use of conventional image classification techniques, as there is not a one-to-one relationship between vegetation and the underlying surficial sediments. The RADARSAT-1 data utilized consists of RADARSAT-1 imagery acquired using Standard Beam 1 and 7 in both ascending and descending passes. Moisture and surface roughness information can be extracted by applying algorithms that calculate the differences between images acquired from different incidence angles and look directions (ascending versus descending looks). The image created using different incidence angles highlights flat surfaces, including wetlands, agricultural areas, and forest fire scars. The image generated using opposing look directions enhances geomorphologic features, including ice flow features, meltwater channels, till hummocks, and sand dune ridges. In addition, the enhanced RADARSAT-1 imagery (includes integration of topographic information provided by a digital elevation model (DEM)) provides an additional level of confidence to the air photo interpretation conducted in regions with little or no ground access and also provides a regional perspective on large-scale subtle surface morphological elements (e.g., ice flow patterns) that might be overlooked in individual aerial photographs.