Glacier Changes in the Susitna Basin, Alaska, USA, (1951–2015) using GIS and Remote Sensing Methods

Abstract

The Susitna River draining from the highly glacierized Central Alaska Range has repeatedly been considered a potential hydro-power source in recent decades, raising questions about the effect of glacier changes on the basin’s river runoff. We determine changes in the glacier area (1951–2010), elevation (1951–2010, 1951–2005 and 2005–2010), equilibrium line altitude (ELA, 1999–2015), and accumulation area ratio (AAR, 1999–2015) of the basin’s five largest glaciers covering 587 km² (2010). We use the Landsat time series, as well as digital elevation models (DEMs) from 1951 (United States Geological Survey (USGS) aerial imagery), 2005 (Advanced Spaceborne Thermal Emission and Reflection Radiometer, ASTER), and 2010 (airborne interferometric synthetic aperture radar, IfSAR). The glaciers lost an area of 128 ± 15 km² (16%) between 1951 and 2010. The mean ELA was located at 1745 ± 88 m a.s.l. during 1999–2015. The glacier’s annual ELAs do not show any significant trends. We found a glacier-wide elevation change of −0.41 ± 0.07 m yr−1 for the period 1951–2005 and −1.20 ± 0.25 m yr−1 for 2005–2010. The results indicate that the glaciers are in a state of retreat and thinning, and have been losing mass at an accelerated rate in recent years. The interpretation of the thickness changes is complicated by the glaciers’ surge cycles.

Keywords

• glacier
• geodetic mass balance
• glacier elevation change
• digital elevation model
• equilibrium line altitude
• accumulation area ratio
• glacier surge
• Susitna basin