Andreas Alexander, Jeffrey A. Tuhtan , Maarja Kruusmaa, Thomas Vikhamar Schuler, Andreas Kääb

Supraglacial channels constitute an important part of the glacial hydrological system, both by influencing surface energy exchange as well as routing meltwater to eventually feed en- and subglacial drainage systems. Subglacial systems have received considerable scientific interest, but specific studies of supraglacial channels are sparse. This limited scientific understanding represents a missing link between meltwater generation and en/subglacial hydraulics; among others it poses a problem for constraining and validating glacier hydrological models. In this study, we utilize drifters carrying a navigation system to obtain the spatial and temporal evolution of the water velocity along a supraglacial channel on Austre Brøggerbreen (Svalbard). This velocity is then used to compute melt rates of the channel walls and to estimate the discharge in the channel. We further present, to our knowledge, the first dataset of the spatio-temporal evolution of the water acceleration in the channel. The highest accelerations occur at the location of step-pool sequences and peaks in the acceleration signal can already be seen before the step-pool sequences have developed in the channel. We therefore conclude that water acceleration can be used to predict where step-pool sequences will form.