Using airborne lidar to assess the influence of glacier downwasting on water resources in the Canadian Rocky Mountains

Knowledge of the changing dimensions of alpine glacier surfaces is critical from both a water resources and climate change indication perspective. With the development of airborne light detection and ranging (lidar) technologies with the capability to rapidly map large areas of topography at high resolutions, there is a need to assess the utility of this technology for glacier surface change detection and water resources assessment. The study presented here compares two lidar digital elevation models (DEMs) collected 23 months apart in 2000 and 2002 over Peyto Glacier, Canadian Rocky Mountains, for the purposes of intensity image feature recognition and surface downwasting assessment. The 2002 DEM was subtracted from the 2000 DEM to quantify the total and spatial variability in surface downwasting (or growth) within the glacial and periglacial environments. It was found that there was a reduction in volume totaling 33 x 10(6) m(3) over the Peyto Glacier surface and surrounding ice-cored moraines. This downwasting was estimated to be equivalent to approximately 22 x 106 m3 of water volume and, after extrapolation, 16% of total basin runoff. The water-equivalent contribution from ice-cored moraines was estimated to be 6% of the total glacier runoff contribution, highlighting the importance of monitoring this component of glacial melt.