A Multi-century Estimate of Suspended Sediment Yield from Lillooet Lake, Southern Coast Mountains, Canada

We use annually laminated lake sediments to estimate suspended sediment yield for a 3850 km2 montane catchment in the British Columbia Coast Mountains. Sediment yield over the past 369 years averages 213 Âą 38 Mg km-2 a-1. Sediment yield increases to 285 Âą 50 Mg km-2 a-1 during the first half of the twentieth century and declines thereafter. The frequency of high-yield events during the 369-year period is irregular: 11 of the 34 events occur in the early part of the twentieth century, a time when glaciers in the watershed underwent major retreat. We fitted a Generalized Extreme Value (GEV) model to estimate quantiles of the sediment yield distribution, and we used epoch analysis to examine persistence in sediment yield following 34 of the largest events. Persistence is greatest for the most extreme events; it is more variable for events that recur, on average, every 10 to 25 years. Our results indicate that sediment yield is linked to long-term changes in sediment supply to the lake. The results of this study extend earlier sediment yield estimates and improve understanding of linkages to watershed geomorphology, recent glacier retreat, and landslides in the Lillooet River watershed.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author