In recent decades, the impacts of climate warming have been especially significant in alpine glaciated regions. Many valley glaciers have decoupled from high-level icecaps to expose major escarpments now experiencing rapid mass wasting by processes dominated by ice, including ice avalanching, rockfalls, icy debris flows, and slush avalanches. This project will conduct the first detailed study of a suite of dynamic ice-dominated landforms (here termed icy debris fans) that are evolving at the base of these escarpments. Previous studies of deglaciating landscapes, formed during periods known as paraglacial, have described rapid development of alluvial fans and talus cones, however, the influence of ice-dominated mass wasting processes on landform evolution has mostly gone unrecognized. Research will occur at study sites in Alaska and New Zealand that provide maximum variety of morphogenetic settings and temporal stages needed to develop an accurate evolutionary model for landforms associated with icy debris fans. This research will focus on field investigations aimed at deciphering the depositional processes that form icy debris fans, the influence of catchment morphometry on fan morphology, and distinguishing sedimentological characteristics of icy fans compared with similar landforms not dominated by ice. By using a novel combination of ground-based LiDAR mapping surveys, time-lapse photography, and remote-control aircraft, we will quantify variations in the rates and volumes of depositional processes and morphology of fans formed in different settings through time. Surficial sedimentological data and subsurface geophysical surveys will document the sedimentary architecture of icy debris fans. Once integrated, these datasets will yield important constraints on the formation and evolution of icy debris fans and hold implications for evaluating landscape evolution through time, including distinguishing the deposits of icy debris fans from related but more thoroughly studied landforms such as alluvial fans and talus cones.
Recent climate warming has had major impacts on glaciers delivering ice from high-level icecaps to lower elevation valley glaciers. Warming has resulted in decoupling of many valley glaciers from their source icecaps, thereby exposing major bedrock escarpments. These escarpments are highly unstable and characterized by extreme erosional processes dominated by ice ? such as ice avalanches, icy debris flows, slush avalanches, and rockfall. Rapidly-forming landforms known as icy debris fans dominate this newly-forming landscape immediately following deglaciation where hundreds of catastrophic ice avalanches and icy debris flows are common during summer weeks. This research directly addresses several key scientific problems linked to modern global warming and will advance research methods of landform analysis in rugged alpine environments by developing a novel methodology involving time-lapse photography, ground-based radar imaging, and remote-controlled aircraft. Given that icy debris fans are newly discovered landforms, our research holds promise for providing new perspectives on the nature of landform evolution in deglaciating alpine environments. The anticipated outcomes will have direct implications towards improving assessment of geohazards and watershed management in deglaciating alpine settings. Specifically, results will provide a better understanding of changes in sediment and water flux downstream, improving our understanding of hazards and safety in back country areas of national parks in Alaska and New Zealand. As glaciers continue to melt and thin in alpine environments, a wide range of glacial hazards are expected to increase, including rockfalls, breakout floods from ice dams, and ice avalanches. Icy debris fans will become more prevalent as slopes become increasingly unstable. Better characterization of the nature and frequency of these poorly understood processes and landforms will help mitigate the impacts of these hazardous phenomena that are affecting increasingly larger geographic regions.
This project is supported by the Geomorphology and Land Use Dynamics Program, NSF's Office of International Science and Engineering, and EAR's Education and Human Resources program.
