Determining ice-jam stage frequency distributions of an ungauged river reach using dendrogeomorphological data

Abstract

ABSTRACT Ice-jam floods are a common, but dangerous natural phenomena occurring in many northern rivers. These events are even more dangerous when only limited gauged river data is available to be used to predict the severity of events in ice-jam prone areas, especially when these areas are close to a community. This study examines an alternative method for gathering ungauged river data for ice-jam flood hazard assessments, specifically the use of dendrogeomorphological methodologies. The most accurate way to gather this information is through collection of cross-sectional samples from trees that have been scarred by past ice-jam events, rather than the collection of core samples. Therefore, cross-sectional sampling methods were chosen for this study. The years and heights of past ice-jam events were then compared to instantaneous maximum water levels collected from a nearby river gauge to evaluate whether the dendrogeomorphological findings were accurate. Our results show that there is a direct correlation between gauged river data and dendrogeomorphological findings, with signs of ice-jamming events identified in the trees from the five highest years of instantaneous maximum water levels. Additionally, a correlation between the peak events in the two data sources was also revealed.