Supraglacial river discharge was measured by monitoring water depth with a custom-built pressure sensor, at 1-minute intervals, and converting depth to discharge with a rating curve established from salt dilution gauging. Here we report 1-hour means of the 1-minute measurements. This method is well suited to supraglacial river gauging as the electrical conductivity of supraglacial melt water is very low. The pressure sensor was installed on the bottom of the channel and was able to move downwards with the ice surface as the channel gradually incised. Full details are provided in the online supplement to Wadham et al. (2016) at https://doi.org/10.5194/bg-13-6339-2016.

Stream discharge into moulin L41A (m3/s), reported as a 1 hour mean of measurements collected at 1 minute intervals. Lower and upper bound of the 95% confidence interval for Q, calculated using statistics for the rating curve (see Wadham et al., 2016, https://doi.org/10.5194/bg-13-6339-2016).