State Water Resources Research Institute Program

Project ID: 2008AK73B
Title: Reconstruction of the Lake Pleistocene Glacial Lake Ahtna, Copper River Basin, Alaska
Project Type: Research
Start Date: 3/01/2008
End Date: 2/28/2009
Congressional District: AK-1
Focus Categories: Floods, Geomorphological Processes, Hydrology
Keywords: ice-dammed lakes, Lake Ahtna, jokulhlaups, paleo-hydrology, Quaternary climate, Copper River basin, outburst floods, glaciofluvial, glaciolacustrine, strandline
Principal Investigators: Loso, Michael Gregg; Loso, Michael Gregg
Federal Funds: $ 15,667
Non-Federal Matching Funds: $ 38,174
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 Ahtna, a massive glacier-dammed lake that formed in Alaska's Copper River basin during the latest Pleistocene in response to impoundment by glaciers advancing from the surrounding mountain ranges. Geologists have long recognized abandoned strandlines, beaches, deltas, and lacustrine sediments in the area as evidence for the existence of Lake Ahtna, 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. The purpose of the proposed research is to continue reconstruction of the paleo-environment associated with late Pleistocene ice-dammed lakes in the Copper River basin, and to better understand the paleo-hydrology of outburst floods from paleo-Lake Ahtna. The proposed work builds upon an existing body of knowledge about Lake Ahtna, and importantly, also upon the results of our previously-funded summer 2007 research. 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.

Progress/Completion Report, PDF

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