The Influence of Glacier Change on Sediment Yield, Peyto Lake, Alberta, Canada

The relation between sediment yield and glaciers at timescales less than a century remains uncertain. Our research examines this relation for the Peyto Lake catchment (51^o 72' N, 116^o 52' W), a 50 km² alpine watershed that includes Peyto Glacier (11 km²). We collected 23 sediment cores from the lake which ranges from 0.5 to 3 m in length. Recovered sediments consist of laminated, inorganic silt clay couplets which can be shown through ¹³⁷Cs activity to be varves. Varve thickness and sediment properties were combined to produce an annual record of specific sediment yield (SSY) for the catchment. We compare SSY to length, area, and volume change of Peyto Glacier from a topographic survey map (AD1917) and from 18 sets of aerial photographs (AD1947-2005) analyzed through standard photogrammetric methods. SSY is also compared to net, summer, and winter mass balance records for the period AD1966 to 2009. Over the period AD1917-2005, SSY averaged 692 ± 267 T km^-2 yr^-1, and no significant trend in yield is observed over the period of study. Following the mid 1920s, decadal SSY abruptly increases and reaches its maximum around the 1940s which coincides with rapid glacier retreat. SSY also abruptly increases after AD1997 and reaches its annual maximum in AD1998 (1549 T km^-2 yr^-1). The SSY record is weakly correlated with net mass balance and area loss of Peyto Glacier, but stronger relations exist between net mass balance and sediment flux for individual sediment cores. We are nearing completion of elevation and volume change calculations, and these measurements will be compared to SSY.