Impacts to Highway 8 British Columbia due to the November 2021 Atmospheric River Event

ABSTRACT: The section of Highway 8 between Spences Bridge and Lower Nicola British Columbia suffered significant damage during the atmospheric river event of November 2021 with multiple sections of the highway completely washed away and destroyed due to flooding and lateral migration of the Nicola River, along with access to small farming and Indigenous communities along the highway cut off. The damage included a total of 6 km of highway that was completed eroded away, with a further 1 km of highway and 3 highway bridges compromised. Additional damage in the corridor included 4 private or secondary road bridges that were washed away, with a further 4 compromised along with 5 bridges associated with the historic Kettle Valley Railway also lost. The damaged through this corridor was significantly amplified in areas due to the vulnerability of glacial drift soils to erosion, the impacts from a wildfire that occurred in the summer of 2021 and the presence of natural and artificial hydraulic constrictions along sections of the Nicola River. The resulting flood damage created multiple geohazards for the response team to contend with including some significant landslide hazards that in one extreme case resulted in an approximately 3 km section of the highway shifted onto the historic Kettle Valley Railway alignment. This paper provides a summary of the impacts that the flood had to the highway, including the influence of hydraulic constrictions and erodible soils, as well as the significant landslide hazards created by the flood and how they were addressed by the flood response team during the emergency access phase (Phase 1).