Evolution of glacial flow and drainage during the ablation season

SummaryProglacial discharge is controlled by the geometry of the glacial drainage network and by meltwater processes. The glacial drainage systems of some alpine glaciers have been characterised using a model based on a proglacial discharge analysis. In this paper, we apply high frequency systemic analysis to data collected from the Baounet Glacier (French Alps) during two successive ablation seasons. Our approach is based on an analysis of the evolution of daily recession curves during the ablation period. The observed data are fitted by a single 〈β〉-coefficient dependant recession law. Changes in 〈β〉 are compared to variations in the daily discharge amplitude and the time lag between air temperature and proglacial discharge. The changes in the 〈β〉 values do not appear to be related to changes in the time lag and the amplitude of the daily discharge. There were significant variations in the 〈β〉-coefficient during the two ablation periods studied here even if there was no time lag or the daily discharge amplitude change. High values of 〈β〉 correspond to high drainage velocities; therefore increases in 〈β〉 values can be used as an indicator of the evolution of the glacier’s internal drainage network.