Hydroclimatic analysis of an ice-scar tree-ring chronology of a high-boreal lake in Northern Québec, Canada

Ice-scars were investigated to reconstruct the ice-flood history of Corvette Lake in Northern Québec in an attempt to determine the hydrological threshold of shore ice and identify the accompanying climatic conditions. The ice-scar record started around 1850 and showed a rapid increase in frequency at the start of the 1930s, while trees damaged by the ice were already mature and established over several decades. The study supports the hypothesis that this shift could correspond to an increase in flood discharge. Hydrological analysis of every event that occurred since 1961, the year during which instrumental recording began, indicated that scar frequency and scar maximum height were strongly correlated with average recession discharge, average flood discharge, peak discharge and flood onset. Ice-scars provided a discontinuous record of discrete events triggered by hydrologic extremes that were used to document the instrumental record using logistic regression. Results from multiple regressions suggested that ice-scars correspond to years with highs in total precipitation from January to March and from May to June, in the sum of degree-days of frost in April, and in the sum of degree-days of heat from October to April. Although imperfect for reconstructing past events, this study exemplifies the potential use of ice-scars for extending the historical record of ice-floods with hydroclimatic significance.