Sean Kraemer
Madson, Austin; Watson, Rachel
Abstract/Description
The Wind River Range of Wyoming, a subrange of the Rocky Mountains, is an alpine region that has seen glacial retreat due to increased temperatures; this retreat has resulted in multiple glacial lake outburst floods (GLOFs). A well-documented example was a GLOF at Grasshopper Glacier in September 2003 that released 3.2 million cubic meters and damaged downstream structures, showing the hazards GLOFs pose to humans. A GLOF that occurred at nearby Mammoth Glacier in 1994 has remained poorly documented, despite the glacier being responsible for a catastrophic GLOF ~260 years before present, which released ~2.2 million cubic meters of water.
This study used imagery from the Landsat series of satellites, which collects earth observation data in the visible and invisible regions of the spectrum, to reveal that the 1994 GLOF is not the only recent GLOF at Mammoth Glacier. In total, this study has identified thirteen GLOFs between 1994 and 2007 using Landsat imagery. Changes in water extents have been quantified with the Normalized Difference Water Index (NDWI), a widely used spectral index for distinguishing surface water extent in satellite images, to identify and date these floods. Combining water extents with elevation datasets has been used to reconstruct the volume of water released during these GLOFs. Additionally, historic newspapers and aerial and ground photography have identified two other likely GLOFs at Mammoth Glacier. Overall, this study has identified fifteen glacier lake outburst floods at Mammoth Glacier; this is the highest concentration of GLOFs in the Rocky Mountains that has been documented since the Missoula floods. Understanding these GLOFs helps protect downstream residents, agriculture, and infrastructure.
