Supporting data for: Rapid ice-marginal lake growth in Alaska driven by glacier retreat through bed overdeepenings

In this study, we mapped ice-marginal glacial lakes in Alaska in 2018 and 2024 using Sentinel-2 optical imagery. We mapped glacier-bed overdeepenings using existing datasets and evaluated how much lake growth has occurred within these mapped overdeepenings as well as how much additional growth is possible. Here we provide seven supporting data products: i) a raster of mapped glacier-bed overdeepenings using best estimate of ice thickness, ii) a raster of glacier-bed overdeepenings using ice thickness plus uncertainty, iii) a raster of glacier-bed overdeepenings using ice thickness minus uncertainty, iv) a 2018 ice-marginal lake shapefile, v) a 2024 ice-marginal lake shapefile, vi) a 2024 ice-marginal lake shapefile joined to glacier-bed overdeepening area, and vii) RGI 6 glacier inventory joined to glacier-bed overdeepening area. 
, Using an existing glacial lake inventory (Rick et al., 2022), we identified glacial lakes in Alaska greater than 0.5 km2 (n=211) for the period 2016 to 2019 (median year 2018). Using Sentinel-2 optical imagery from 1 May to 30 September 2018 and 2024, we manually mapped lake extents at 1:10,000 scale for these two years in the open-source QGIS software program. We estimate error in lake area by multiplying the lake perimeter (in km) by half the Sentinel-2 pixel resolution (5 m or 0.005 km). We also reviewed and updated the lake connection category, which describes the lake's spatial relationship to its source glacier. These categories include: proglacial (lakes at terminus of glacier, in contact with the ice), supraglacial (lakes on surface of glacier ice), ice (ice-dammed lakes found at ice margins or tributary valleys), detached (lakes fed by glaciers but not in contact with the ice), or unconnected (detached lakes that are not fed by glaciers). This study solely assesses ice-marginal..., # Supporting data for: Rapid ice-marginal lake growth in Alaska driven by glacier retreat through bed overdeepenings

Dataset DOI: [10.5061/dryad.rjdfn2zrc](https://doi.org/10.5061/dryad.rjdfn2zrc)

## Description of the data and file structure

There are two glacial lake outline shapefiles : **Lake_Outlines_2018_102225** and **Lake_Outlines_2024_102225**. The shapefiles consist of a .shp file (feature geometry), along with supporting files (.shx - positional index of the feature geometry, .dbf - columnar attributes for each shape, .prj - project description, .cpg - used to specify the code page). Both are projected in EPSG:3338.

Column Headers in these files include:

**Lake_Outlines_2018_102225**

Latitude: Latitude in decimal degrees in WGS84 format

Longitude:  Longitude in decimal degrees in WGS84 format

Area_2018:  Lake Area in km^2^ from Rick et al., 2022

Area_2018r: Revised Lake Area in km^2^ using 2018 Sentinel-2 imagery

Dam_Type: Material damming lake; see Rick et al., 202...,