Analyses statistiques des conditions climatiques propices aux chutes de blocs de glace dans les corridors routiers du nord de la Gaspésie, Québec, Canada

摘要

In Northern Gaspésie, ice-block falls threaten the road network. The ice blocks come from the thaw and collapse of rockwall ice. Superficial ice formations grow every year on some rock cliffs. Field observation provided deeper understanding of these ice formations' growth dynamics, thaw, and flow. Between 2000 and 2006, the Quebec Ministry of Transportation realized 232 operations to clear out the fallen ice blocks from the road. The interventions were compared with climatic data obtained from the nearest weather station. Ice-block fall occurrence probability was calculated from logistical regression models. The degree day (DD) of thaw is the predominant variable. It represents the sum of mean daily temperatures above 0 °C. Furthermore, the restricted variability from year-to-year of the DD is presented in the context of forecasting the collapse of some specific rockwall ice. The potential use of the models as a tool for predicting ice-block falls is also discussed.