Suspended sediment variations in a glacierized alpine catchment

Glacierized basins constitute a significant source of suspended sediment, but previous attempts to identify sediment sources, processes and storage have been compromised by inadequate spatial and temporal sampling. Suspended sediment was collected during summer 1994 at Small River Glacier, British Columbia, using hourly automatic sampling and turbidimetry on supraglacial and "submarginal" glacial streams, and at proximal and distal proglacial sites. Hourly sampling adequately described the diurnal signal, but higher sampling frequency is needed to characterize storm response. Turbidimetry proved valuable only over short time intervals.;Supraglacial sources delivered little suspended sediment, whereas extraglacial snow melt or storm runoff dominated the submarginal stream signal. Massive increases in suspended sediment occurred in the proximal proglacial setting where an ice-contact stream was rapidly eroding steep, ice-contact, saturated till. In the absence of a proglacial stream, the distal proglacial environment delivered suspended sediment only during rain storms.;The dominant proximal proglacial source of suspended sediment was limited in volume, and sustained erosion was contingent on glacier retreat. Distal proglacial sources may be more active during spring runoff, and glacial stream channels may act as both sources and sinks for sediment.