State Water Resources Research Institute Program


Project ID: 2007AK65B
Title: Geomorphic constraints on the configuration, magnitude, and timing of late-Quaternary megafloods from glacier-dammed Lake Atna, Alaska
Project Type: Research
Start Date: 3/01/2007
End Date: 2/28/2008
Congressional District: AK
Focus Categories: Geomorphological Processes, Floods, Climatological Processes
Keywords: Lake Atna, geomorphology, floods, ice-dammed lakes, Quaternary climate, paleohydrology, lacustrine sedimentation
Principal Investigator: Loso, Michael Gregg
Federal Funds: $ 18,124
Non-Federal Matching Funds: $ 36,410
Abstract: There are over 700 glacier-dammed lakes in Alaska. While some are shrinking or disappearing in response to contemporary warming and glacier retreat, surprisingly new lakes are forming as well. Because these lakes typically drain catastrophically on an irregular basis, posing threats to human life, property, and infrastructure, and also because such lakes create and leave behind many landforms and sedimentary deposits that have important and long-lasting effects on landscape hydrology, it is important that we better understand the interrelated geomorphic and climatic factors that govern the formation, catastrophic drainage, and abandonment of glacier dammed lakes. Here, we propose a geomorphic investigation of paleo-Lake Atna, a massive glacier-dammed lake that formed in Alaska's Copper River basin during the latest Pleistocene and early Holocene in response to impoundment by glaciers of the eastern Chugach Mountains. Geologists have long recognized abandoned strandlines, beaches, deltas, and lacustrine sediments in the area as evidence for existence of Lake Atna, but most work on these landforms predated sophisticated survey, mapping, and dating tools. Our work will combine traditional geological fieldwork with sophisticated survey, mapping, and dating tools to provide a new, comprehensive spatial database of previously-identified and new Lake Atna landforms to constrain the configuration, magnitude, and timing of megafloods associated with drainage(s) of the lake. Our analysis of these data will include estimates of lake heights and volumes, spillway locations, flood pathways and magnitudes, subsequent isostatic effects, and relationships to known Quaternary climate trends. Support is requested primarily for graduate student salary and AMS radiocarbon dates; mentoring will be provided by research collaborators from Alaska Pacific University, US Geological Survey, and the Bureau of Land Management.

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