Preprints
https://doi.org/10.5194/tc-2021-143
https://doi.org/10.5194/tc-2021-143

  08 Jun 2021

08 Jun 2021

Review status: this preprint is currently under review for the journal TC.

Dam type and topological position govern ice-marginal lake area change in Alaska and NW Canada between 1984 and 2019

Brianna Rick1, Daniel McGrath1, William Armstrong2, and Scott W. McCoy3 Brianna Rick et al.
  • 1Department of Geosciences, Colorado State University, Fort Collins, CO 80523, USA
  • 2Department of Geological and Environmental Sciences, Appalachian State University, Boone, NC 28607, USA
  • 3Department of Geological Sciences and Engineering, University of Nevada, Reno, NV 89557, USA

Abstract. Ice-marginal lakes impact glacier mass balance, water resources, and ecosystem dynamics, and can produce catastrophic glacial lake outburst floods (GLOFs) via sudden drainage. Multitemporal inventories of ice-marginal lakes are a critical first step in understanding the drivers of historic change, predicting future lake evolution, and assessing GLOF hazards. Here, we use Landsat-era satellite imagery and supervised classification to semi-automatically delineate lake outlines for four ~5 year time periods between 1984 and 2019 in Alaska and northwest Canada. Overall, ice-marginal lakes in the region have grown in total number (+176 lakes, 36 % increase) and area (+467 km2, 57 % increase) between the time periods of 1984–1988 and 2016–2019. However, changes in lake numbers and area were notably unsteady and nonuniform. We demonstrate that lake area changes are connected to dam type (moraine, bedrock, ice, or supraglacial) and topological position (proglacial, detached, unconnected, ice, or supraglacial), with important differences in lake behavior between the sub-groups. In strong contrast to all other dam types, ice-dammed lakes decreased in number (−9, 13 % decrease) and area (−56 km2, 43 % decrease), while moraine-dammed lakes increased (+59, 28 % and +468 km2, 85 % for number and area, respectively), a faster rate than the average when considering all dam types together. Proglacial lakes experienced the largest area changes and rate of change out of any topological position throughout the period of study. By tracking individual lakes through time and categorizing lakes by dam type, subregion, and topological position, we are able to parse trends that would otherwise be aliased if these characteristics were not considered. This work highlights the importance of such lake characterization when performing ice-marginal lake inventories, and provides insight into the physical processes driving recent ice-marginal lake evolution.

Brianna Rick et al.

Status: open (until 03 Aug 2021)

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Brianna Rick et al.

Data sets

Multi-decadal Glacial Lake Inventory in the Alaska Region between 1984 and 2019 Brianna Rick and Daniel McGrath https://arcticdata.io/catalog/view/doi:10.18739/A2MK6591G

Brianna Rick et al.

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Short summary
Glacial lakes impact societies as both resources and hazards. Lakes form, grow, and drain as glaciers thin and retreat, and understanding lake evolution is a critical first step in assessing their hazard potential. We map glacial lakes in Alaska between 1984 and 2019. Overall, lakes grew in number and area, though lakes with different damming material (ice, moraine, bedrock) behaved differently. Namely, ice-dammed lakes decreased in number and area, a trend lost if dam type is not considered.