Commentary on “Past variation in Lower Peace River ice-jam flood frequency” by Wolfe et al. (2020)

Abstract

In contrast to a large body of scientific literature that is based on empirical data and physically based and mathematical analyses, Wolfe et al. (2020) cited proxy-based paleolimnological evidence and argued that the regulation of Peace River has not played a role in the reduced incidence of large ice-jam floods. Such events are essential to the sustenance of perched basins located in the Peace Sector of the Peace–Athabasca Delta. Herein, the arguments advanced by Wolfe et al. (2020) are critically examined and shown to be unconvincing. Relevant literature indicates that a drying trend was first noticed after construction of the Bennett Dam. It is shown, moreover, that the belatedly questioned Traditional Knowledge and Historical ice-jam flood record is a reliable source of information, at least with respect to large floods, which are crucial to perched-basin replenishment. Detailed examination of the Wolfe et al. (2020) magnetic susceptibility (MS) profiles and their interpretation points to serious inconsistencies and leads to a renewed recommendation for coring perched, rather than readily flooded, basins in the future. It is also recommended that the oxbow lakes cored nearly two decades ago be revisited to obtain updated MS profiles. Deficiencies in the interpretation of inferred isotopic-composition time series of three perched basins suggest that all factors influencing such environmental variables be considered before drawing conclusions regarding the frequency of past floods.