Use of historical elevation data to calculate surface-elevation and volume changes of Ha-lltzuk Icefield, southwest British Columbia, Canada, 1970 to mid-1980s

摘要

Investigations into glacial changes, including understanding variations in the rates of glacial volume and surface-elevation changes, have increased over the past decade. This study uses historical glacier elevation data in the form of topographic maps from 1970 and a digital elevation model from the mid-1980s to calculate surface-elevation and volume changes for Ha-lltzuk Icefield, southwest British Columbia, Canada. Results indicate that the icefield thinned at an average rate of 0.76 ± 0.25 m a~(-1) during this period. A previous study of Ha-lltzuk Icefield also using the geodetic method found a thinning rate of 1.0 ± 0.20 m a~(-1) between the mid-1980s and 1999, indicating a slight increase in the amount of icefield thinning. Within the ablation zone, thinning increased with decreasing elevation at a rate of 1.9 ± 0.68 m a~(-1) km~(-1) between these two periods (1970 to mid-1980s versus mid-1980s to 1999). Analysis of meteorological data suggests that increases in both temperature and rainfall, as well as decreases in snowfall, likely contributed to the increased thinning rate.