The rapid drainage of supraglacial lakes introduces large pulses of meltwater to the subglacial environment and creates surface-to-bed conduits for future melt. Introduction of water to the subglacial system has been shown to affect ice flow and modeling suggests that variability in water supply and delivery to the subsurface play an important role in the development of the subglacial hydrologic system and its ability to mitigate or enhance ice flow. We developed a fully automated method for tracking meltwater and rapid drainages in 78 large, perennial lakes along an outlet glacier flow line in West Greenland from 2002 to 2011 using ETM+ and MODIS imagery. Results indicate interannual variability in maximum coverage and spatial evolution of total lake area. We identify 238 rapid drainage events, occurring most often at low and middle elevations during periods of net filling or peak lake coverage. We observe a general progression of both lake filling and draining from lower to higher elevations but note that the timing of filling onset, peak coverage, and dissipation are also variable. While lake coverage was sensitive to air temperature, warm years exhibited greater variability in both coverage evolution and rapid drainage. Mid elevation drainages in 2011 coincide with large surface velocity increases at nearby GPS sites, though the relationships between iceshed-scale dynamics and meltwater input are still unclear.
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