Author(s): Heyu Fang; Yuntong She; Mark Loewen; Benoit Turcotte
Linked Author(s): Mark R. Loewen, Yuntong She
Keywords: Overflow events; Aufeis process; Flooding; Small-steep-regulated river
Abstract:
Overflow events are common in small-steep-regulated rivers. They are particularly impactful in winter, when the overflowing water freezes in successive layers on the ground or an existing ice surface, leading to the formation of aufeis. Frequent overflow events lead to extensive aufeis formation, which poses significant flood risks and affects both public and private properties. Despite their prevalence, there have been relatively few quantitative studies of winter overflow events. In this study, hydrometeorological data collected over three winters on the Aishihik River, a small-steep-regulated river in Yukon, Canada, were used to quantitatively investigate the properties and mechanisms of overflow events. A total of 314 overflow events were identified based on field time-lapse images and water levels measured near the camera sites. Results showed that overflow events occurred from November to April, varied in frequency by month and location, with 90% lasting less than 24 hours. Eighteen overflow events were analyzed in detail in conjunction with the environmental conditions and two overflow mechanisms were identified. Water level rise due to anchor ice and/or border ice processes were the main causes of overflow events during freeze-up periods, while overflow events that occurred during the ice-covered period corresponded closely with the discharge fluctuations due to flow regulation.
Year: 2024