Observing and Modeling Drainage Networks from Supraglacial Lakes on Russell Glacier, West Greenland

Abstract:

Formation and drainage of supraglacial lakes on the margin of the Greenland ice sheet is a crucial component of ice sheet surface ablation, development of supra-glacial meltwater streams and ice dynamics. This study aims to understand and predict patterns of supraglacial lake drainage over an entire melt season on a section of the western Greenland Ice Sheet near Russell Glacier. To gain qualitative understanding of the development of lakes over the melt season, we first examined locations of lakes using LANDSAT imagery. The large lakes initiated at low elevation early in the melt season, before forming at increasingly higher elevations as the summer progressed. Near the end of the melt season, the lakes at higher elevations disappeared at the same time as lower elevations reformed and increased in surface area. Given these initial results, a one-dimensional model of supraglacial lake drainage was made based on a digital elevation model (DEM) and temperature data. In the model, water was routed downstream based on the direction of steepest slope in DEM. We used a temperature index model to estimate melt rates and flow rates downstream. Preliminary results show that the location of depressions in the DEM corresponds to the locations of large lakes (>500,000 m²) and supra-glacial streams are well approximated by the direction of steepest slope. Moreover, our model shows that the lakes at higher elevations overtop and drain downstream, causing an increase in lake area in lower elevations near the end of the melt season.