Icing and aufeis in cold regions I: the origin of overflow

The process of icing involves the freezing of overflow layers, on ground or within streams, and results in ice bodies called “aufeis” that are common in most northern landscapes. Knowledge about aufeis is still limited despite the cold region engineering challenge they represent. Understanding the causes of overflow events leading to aufeis development represents a key for the prediction, mitigation, and management of this geohazard, and can also support the planning and design of infrastructure in the North. This paper introduces a practical classification for the diverse range of overflow processes that generate aufeis, including underrepresented processes, such as the instability of winter streamflow. Importantly, it distinguishes flow conveyance from water supply overflow processes and describes the temporal aspect of icing intensity. Finally, research topics are proposed to improve our understanding of aufeis, including their predictability, the impact of climate change on their occurrence and extent, and stream morphology-aufeis interaction.