Dam type and lake location characterize ice-marginal lake area change in Alaska and NW Canada between 1984 and 2019

Abstract. Ice-marginal lakes impact glacier mass balance, water resources, and ecosystem dynamics can produce catastrophic glacial lake outburst floods (GLOFs) via sudden drainage. Multitemporal inventories of ice-marginal are a critical first step in understanding the drivers historic change, predicting future evolution, assessing GLOF hazards. Here, we use Landsat-era satellite imagery supervised classification to semi-automatically delineate outlines for four ∼5-year time periods between 1984 2019 Alaska northwest Canada. Overall, region have grown total number (+183 lakes, 38 % increase) area (+483 km2, 59 1984–1988 2016–2019. However, changes numbers were notably unsteady nonuniform. We demonstrate that connected dam type (moraine, bedrock, ice, or supraglacial) topological position (proglacial, detached, unconnected, supraglacial), with important differences behavior sub-groups. In strong contrast all other types, ice-dammed decreased (six fewer, 9 decrease) (−51 40 decrease), while moraine-dammed increased (56 more, 26 +479 87 increase area, respectively) at faster rate than average when considering types together. Proglacial experienced largest change out any throughout period study which increases associated clean-ice glaciers (<19 debris cover). By tracking individual through categorizing by type, subregion, position, able parse trends would otherwise be aliased if these characteristics not considered. This work highlights importance such characterization performing provides insight into physical processes driving recent evolution.