HOW DO GLACIER EROSION RATES VARY ACROSS THE CANADIAN CORDILLERA?

Few would argue that glaciers are erosive agents, but no unifying theory of glacier erosion exists. Varied bedrock, climate, and sparse observations all conspire to limit our ability to quantify sediment production in glacierized watersheds. Lacustrine- and fluvial-based estimates of sediment yield from proglacial catchments support the general hypothesis that sediment erosion increases with ice cover. But is this increase due to elevated rates of subglacial erosion or reworking of sediments beneath and adjacent to contemporary ice masses? We investigate how glacier erosion rates vary across the Canadian Cordilleran with numerical modeling. Our model simulates subglacial abrasion and quarrying, and we use the model to estimate glacier erosion within watersheds of differing glacier cover, lithology, and climate. Distributed mass balance fields are derived from contemporary precipitation and temperature fields to produce glacier extents comparable to those of today. We evaluate our estimates of sediment production beneath contemporary glaciers to reported rates of glacier erosion; we also convert our erosion rates to estimates of sediment yield for basins where measurements of sediment yield exist. In addition to clarifying the importance of climate and lithology in sediment erosion, our findings highlight the importance of sediment storage in glacierized watersheds.