Hydro-meteorological drivers and sources of suspended sediment flux in the pro-glacial zone of the retreating Castle Creek Glacier, Cariboo Mountains, British Columbia, Canada

摘要

Glaciers are major agents of erosion that increase sediment load to the downstream fluvial system. The Castle Creek Glacier, British Columbia, Canada, has retreated similar to 1.0km in the past 70 years. Suspended sediment concentration (SSC) and streamflow (Q) were monitored independently at five sites within its pro-glacial zone over a 60 day period from July to September 2011, representing part of the ablation season. Meteorological data were collected from two automatic weather stations proximal to the glacier. The time-series were divided into hydrologic days and the shape and magnitude of the SSC response to hydro-meteorological conditions ('cold and wet', 'hot and dry', 'warm and damp', and 'storm') were categorized using principal component analysis (PCA) and cluster analysis (CA). Suspended sediment load (SSL) was computed and summarized for the categories. The distribution of monitoring sites and results of the multivariate statistical analyses describe the temporal and spatial variability of suspended sediment flux and the relative importance of glacial and para-glacial sediment sources in the pro-glacial zone. During the 2011 study period, similar to 60% of the total SSL was derived from the glacial stream and sediment deposits proximal to the terminus of the glacier; during 'storm' events, that contribution dropped to similar to 40% as the contribution from diffuse and point sources of sediment throughout the pro-glacial zone and within the meltwater channels increased. While 'storm' events accounted for just 3% of the study period, SSL was similar to 600% higher than the average over the monitoring period, and similar to 20% of the total SSL was generated in that time. Determining how hydro-meteorological conditions and sediment sources control sediment fluxes will assist attempts to predict how pro-glacial zones respond to future climate changes. Copyright (C) 2015 John Wiley & Sons, Ltd.