Distribution and morphology of moulins at Isunnguata Sermia, West Greenland 

Abstract

This study presents high resolution mapping of moulins located above three subglacial lakes at Isunguata Sermia. Moulins are the primary pathway for transferring supraglacial melt to englacial and subglacial environments. The formation of moulins has been explained by the flow of water into a notch, associated with glacier structures and incision of supraglacial streams, which are directly related to glacier morphology and dynamics. Meltwater input to subglacial systems, along with glacier dynamics, will in turn affect the development of subglacial meltwater networks, which control glacier morphology and dynamics. This study focusses on Isunguata Sermia, West Greenland, which has an active subglacial drainage system that includes distinct subglacial lakes. Hydrologically connected or active subglacial lakes may be directly influenced by water input from supraglacial to englacial systems via moulins during the ablation season. Moulins were mapped using a combination of high resolution orthomosaics and digital elevation models derived from uncrewed aerial vehicle flights. Moulin locations and morphologies were compared with glacier structures, ice flow velocities, and bed topography. We reveal a distinct pattern of moulin locations relative to each subglacial lake and the locations of primary and secondary glacier structures an supraglacial hydrology. Furthermore, we also outline a clear morphological pattern, wherein morphology of moulins varies distinctly at with the location of each subglacial lake between vertical shafts, crevasse associated and keyhole morphology. These observations will be used to consider the efficiency of meltwater routing from the surface to the bed, and the potential for inputs to subglacial lakes, and the wider implications for varying ice flow velocity and evolution of the subglacial drainage system.