Subglacial hydrology is critical to understand the behaviour of ice sheets, yet active meltwater drainage beneath contemporary ice sheets is rarely accessible to direct observation. Using geophysical and sedimentological data from the deglaciated western Ross Sea, we identify a palaeo-subglacial hydrological system active beneath an area formerly covered by the East Antarctic ice sheet. A long channel network repeatedly delivered meltwater to an ice stream grounding line and was a persistent pathway for episodic meltwater drainage events. Embayments within grounding-line landforms coincide with the location of subglacial channels, marking reduced sedimentation and restricted landform growth. Consequently, channelized drainage at the grounding line influenced the degree to which these landforms could provide stability feedbacks to the ice stream. The channel network was connected to upstream subglacial lakes in an area of geologically recent rifting and volcanism, where elevated heat flux would have produced sufficient basal melting to fill the lakes over decades to several centuries; this timescale is consistent with our estimates of the frequency of drainage events at the retreating grounding line. Based on these data, we hypothesize that ice stream dynamics in this region were sensitive to the underlying hydrological system.

冰河下的水文学对于了解冰盖的行为至关重要，但是很难直接观察到当代冰盖下的融化融水。利用来自西部冰川海中冰河的地球物理和沉积学数据，我们确定了一个活跃于南极东部冰原以前覆盖的区域下面的古冰下水文系统。一个长通道网络反复将融化水输送到冰流接地线，并且是突发性融化水排放事件的持续路径。接地线地貌内的沉积物与冰下渠道的位置相吻合，标志着沉积减少和地貌生长受限。因此，地线上的沟渠排水影响了这些地貌向冰流提供稳定性反馈的程度。通道网络与最近发生地质裂谷和火山活动的上游冰川下湖泊相连，在那里高的热通量会产生足够的基础融化作用，从而在数十年至几个世纪的时间里将湖泊填满。此时间范围与我们对后撤接地线上排水事件发生频率的估计一致。基于这些数据，我们假设该地区的冰流动力学对基础的水文系统敏感。