Objective preliminary assessment of outburst flood hazard from moraine-dammed lakes in southwestern British Columbia.

摘要

An objective, remote sensing-based procedure is proposed to evaluate the outburst flood hazard posed by moraine-dammed lakes in southwestern British Columbia. Outburst probability is estimated using an expression derived from statistical analysis of data collected from 175 moraine-dammed lakes in the southern Coast Mountains. Logistic regression identified four factors that correctly discriminate 70% of drained and 90% of undrained lakes: moraine height-to-width ratio, presence/absence of an ice core in the moraine, lake area, and main rock type forming the moraine. Objective methods, which incorporate empirical relations applicable to the study region, are used to predict outburst peak discharge and debris flow volume, travel distance, and area of inundation. Outburst flood hazard is especially sensitive to lake level fluctuations and is greatest for large lakes perched on valley sides behind narrow, ice-free moraine dams composed of sedimentary rock debris.