Five centuries of interannual sediment yield and rainfall-induced erosion in the Canadian High Arctic recorded in lacustrine varves

A 487-year sediment yield record based on the varves from Nicolay Lake, Nunavut, Canada, is used to investigate long-term yield variability. A general extreme value model, estimated with probability-weighted moments, was used to identify the magnitude and timing of the low-probability events. Exceptional sediment yields in 1951 and 1962 coincided with the two largest rainfalls on record. Smaller multiday rainfalls were also recorded in the varves as subannual rhythmites, although rhythmites were not generated by rainfall events that occurred during the nival flood or after prolonged warm weather. By accounting for probable soil moisture conditions and the timing of nival floods compared to major rainfall, rhythmites in all but 3 years of the sediment record can be explained by storms exceeding similar to 13 mm total. Generally, more frequent extremes and increased variance in yield occurred during the 17th and 19th centuries, likely due to increased occurrences of cool, wet synoptic types during the coldest periods of the Little Ice Age.