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TitleAssessment of storm surge history as recorded by driftwood in the Mackenzie Delta and Tuktoyaktuk Coastlands, Arctic Canada
AuthorMacLeod, R FORCID logo; Dallimore, S RORCID logo
SourceFrontiers in Earth Science vol. 9, 698660, 2021 p. 1-16, Open Access logo Open Access
Alt SeriesNatural Resources Canada, Contribution Series 20210424
PublisherFrontiers in Earth Science
Mediapaper; digital; on-line
File formatpdf
NTS107B; 107C
Lat/Long WENS-136.0000 -132.0000 70.0000 68.0000
Subjectsenvironmental geology; Nature and Environment; storms; erosion; coastal erosion; coastal studies; coastal environment; climate, arctic; Mackenzie Delta; Tuktoyaktuk Formation
Illustrationslocation maps; aerial photographs; tables; figures; photographs
ProgramPublic Safety Geoscience Plate Boundary Earthquakes
Released2021 12 07
AbstractThe southern Beaufort coastline in Canada experiences significant storm surge events that are thought to play an important role in coastal erosion and influence permafrost dynamics. Unfortunately, many of these events have not been documented with tide gauge records. In this paper, we evaluate coastal driftwood accumulations as a proxy for estimating maximum storm surge heights and the history of these events. We use historical air photos and data derived from Unoccupied Aerial Vehicle (UAV) imagery to resurvey four coastal stranded driftwood study sites that were first appraised in 1985-86 and assess two new regional sites in the Mackenzie Delta. Maximum storm surge heights were found to be similar to observations carried out in the 1980s, however, we refine the elevations with more accuracy and reference these to a vertical datum appropriate for incorporating into sea level hazard assessments. Detailed mapping, historical air photo comparisons and the UAV acquired imagery at a site close to Tuktoyaktuk demonstrate that the highest storm surge at this site (1.98 m CGVD2013) occurred in association with a severe storm in 1970. This event shifted driftwood and floated material slightly upslope from an older event thought to occur in 1944 that reached 1.85 m (CGVD2013) elevation. The quality and accuracy of the high-resolution Digital Surface Model (DSM) and orthophoto derived from Structure from Motion (SfM) processing of the UAV photographs allowed mapping of four distinct stratigraphic units within the driftwood piles. Based on variations in anthropogenic debris composition, weathering characteristics and history of movement on aerial photographs, we conclude that no storm surge events at Tuktoyaktuk have exceeded ~1.3m (CGVD 2013) since 1970. While there has been some speculation that ongoing climate change may lead to more frequent large magnitude storm surges along the Beaufort coast, our study and available tide gauge measurements, suggest that while moderate elevation storm surges may be more frequent in the past several decades, they have not approached the magnitude of the 1970 event.
Summary(Plain Language Summary, not published)
Rare, very large storms occur along the southern Beaufort Sea coastline in Canada. These storms cause widespread flooding and rapid coastal erosion. The consequences of these storms can be significant to the communities, infrastructure and ecology of the area. The height and frequency of these events is largely unknown yet is important to understand for geohazard assessment. We looked at the placement of older driftwood stranded on land during past storms to establish how high the water levels have gone. We additionally looked at the changes in the positions of wood at these locations using current and historical aerial photos to establish when the largest storms have occurred. We found that through using techniques outlined in this paper, we could not only accurately measure the height of the driftwood but also look at the patterns and characteristics of the wood to establish how often storms produce significant water levels. We found that the largest storms occurred in 1944 and 1970, that there is no indication of earlier storms reaching the height of these events and no storms have since come to within 0.7 m in elevation.

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