The net volumetric loss of glacier cover within the Bow Valley above Banff, 1951-1993

Three methods have been used to explore the volumetric change of glaciers in the Bow Basin above Banff forthe years 1951 to 1993. Using aerial photography, the extent of glacier covers for the two years were mapped at a scale of 1 :50,000. The first volumetric calculation of glacier loss was based on inventory criteria (Stanley, 1970); the second a hypsographic curve method based on Young's investigations in Mistaya Basin (1991) and the third; stereo air photogrammetry and DEM comparisons using the computer software package Surfer. These methods were applied to the highly glacierized Hector Lake catchment within the Bow Valley and then extrapolated up to the whole basin above Banff. Reasonable agreement was achieved between the methods and the magnitude of net glacier loss from 1951 to 1993 is estimated to be 1100 to 1650 m³ x 10^6. The true value for volumetric change is considered to be towards the upper end of the range given, due to the likelihood for systematic underestimation during the extrapolation up to the basin above Banff.