Interannual and Seasonal Evolution of Supraglacial Channel Networks on Nivlisen Ice Shelf, East Antarctica

Abstract. Supraglacial channel networks (SCNs) represent critical components of the surface drainage system on Antarctic ice shelves, facilitating the redistribution of meltwater, including into and out of supraglacial lakes, potentially influencing ice-shelf stability. However, the seasonal and interannual variability in their spatial extent, structural evolution, and climatic sensitivity remain poorly quantified, particularly compared to observations of supraglacial lakes. In this study, we investigate the interannual evolution of SCNs on Nivlisen Ice Shelf in East Antarctica between 2017 and 2024 using Sentinel-2 and Landsat-8 satellite imagery, with a detailed seasonal analysis during the 2018–2019 melt season. Key metrics including surface water area, total channel length, number of SCNs, and the number of individual channels were derived to quantify the drainage evolution and system connectivity and complexity. We find significant interannual variability in SCN count (from 34 to 186) and total channel length (from 345 to 1275 km), with peak length of channels observed in 2018. During the 2018–2019 melt season SCNs progressively integrated and connected to form an efficient drainage system, which then fragmented towards the end of the melt season. We find that SCNs are strongly influenced by the ice shelf surface structures and ice surface undulations at a range of scales, with larger channels reforming in the same location. Correlation analysis shows that annual SCN evolution is tightly coupled to regional air temperature, with surface water extent and network connectivity strongly linked to reanalysis-based temperature outputs (r > 0.9, p < 0.05). Snow had variable effects, depending on its timing and how readily it could be melted. Our findings underscore the important dynamic nature of supraglacial channels in redistributing meltwater on Antarctic ice shelves.