Ice Jams in Straight and Sinuous Channels: Insights from Small Flumes

Abstract

This paper presents insights from two small flumes used to compare ice conveyance and jam initiation between straight and sinuous channels of rectangular cross section, and to investigate ice accumulation and jam morphology in sinuous channels. The findings indicate conditions, expressed in terms of Froude number and ice-piece size relative to channel width, limiting ice conveyance and leading to jam initiation in sinuous and straight channels. The sinuous channel is found to have a larger capacity to convey ice floes than the straight channel of the same flow cross section. Velocity nonuniformity, including higher velocities near the outer bank of bends, contributes to this insight. Jams formed by relatively small floes have a nonuniform thickness through the sinuous channel and are thickest along the inner banks. The thickness variation reduces as floe size increases. Accumulation and jam morphology are analogous to alluvial sediment morphology in sinuous channels. The paper also presents suggestions for aspects in need of further laboratory and numerical investigation and further field observations.