Most glacial erosion models assume that erosion rates are proportional
to ice-sliding velocity. While recent studies have shown that water
plays a major role in modulating sliding velocities, the impact it might
have on erosion rates is still unclear. Here we incorporate subglacial
hydrology into a glacial erosion model that is based on a sliding rule.
Our results explicitly highlight that adding subglacial hydrology has
profound impacts on the temporal and spatial patterns of glacial
erosion. First, it suggests that erosion might mainly occur during
melting seasons, when subglacial water pressure is large and effective
pressure is low (i.e., before the channels fully develop and reduce the
water pressure at the ice bedrock interface), which promotes sliding and
erosion. Second, the distribution of erosion is bimodal with a peak at
the equilibrium line altitude and, as we demonstrate, enhanced erosion
at much lower altitudes within the ablation area where water due to
melting abounds. This has important implications because it explains why
glacial erosion can simultaneously set a limit on the mean elevation of
mountain ranges and carve large fjords or glacial lakes. (C) 2011
Elsevier B.V. All rights reserved.