DETECTING GLACIAL OUTBURST FLOODS ON LEMON GLACIER, SOUTHEASTERN ALASKA: A PAIRED WATERSHED APPROACH

A time-series discharge comparison of two watershed, one glaciated, one non-glaciated, in southeastern Alaska yielded a possible means of remotely detecting drainage of glacial impounded water-bodies. In 1956 the Juneau Icefield Research Program (JIRP) discovered a system of lakes, caves, and sub/englacial cavities on Lemon Glacier that seasonally fill with water and drain into Lemon Creek during mid to late summer. Because there are very few measurements of these glacial outbursts, the behavior, mechanisms, and changes in this system are not well understood. Discharge from Lemon Creek watershed (area 32.6 km2) was compared to that from a nearby, similarly sized, non-glaciated watershed, Gold Creek, (area 23.8 km2), ~ 8 km SE of Lemon Creek. The U.S. Geological Survey has been gauging these two watersheds since the mid-1950. Lemon Creek’s glacial outbursts were observed during the 1967 and 2001 field seasons. Using a variety of comparative watershed techniques, probable dates on which glacial outbursts occurred were determined throughout the discharge record. The outburst dates indicated by comparing paired watershed discharge generally agreed with observed dates. This type of analysis may provide insights into the evolution of seasonally draining glacial impounded water-bodies.