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TitleVariability of coastal change along the western Yukon coast
AuthorKonopczak, A M; Manson, G K; Couture, N J
SourceGeological Survey of Canada, Open File 7516, 2014, 81 pages,
PublisherNatural Resources Canada
Documentopen file
Mediaon-line; digital
File formatpdf
NTS117A/08; 117A/09; 117A/10; 117A/13; 117A/14; 117A/15; 117A/16; 117C/01; 117C/07; 117C/08; 117D/02; 117D/03; 117D/04; 117D/05; 117D/06; 117D/12
AreaYukon Coast; Beaufort Sea; Komakuk; Kay Point; Herschel Island
Lat/Long WENS-141.0000 -136.2500 69.7500 68.2500
Subjectsmarine geology; surficial geology/geomorphology; coastal environment; coastal studies; coastal erosion; coastal management; vegetation; terrain management; global positioning system surveys
Illustrationstables; location maps; aerial photographs; photographs; models; flow charts; plots
Natural Resources Canada Library - Ottawa (Earth Sciences)
ProgramCoastal Infrastructure, Climate Change Geoscience
Released2014 04 09
AbstractBecause the Yukon coast along the Beaufort Sea has the highest ground ice contents in the Canadian Arctic and, in addition, faces the direction of most effective storms, this section of coast is considered to be highly vulnerable to the effects of climate change. In order to gain insight into the regional coastal dynamics, a quantification of coastal change was undertaken that allowed the determination of spatial and temporal variability of coastal change along a 35 km long section of coast, stretching from Komakuk to the international border. Shorelines from several years between 1951 and 2009 were digitized from georeferenced aerial photographs and an ortho-rectified SPOT image. Shoreline change statistics were subsequently calculated using the Digital Shoreline Analysis System (DSAS) extension for Esri ArcGIS. Theodolite and real-time kinematic GPS data that was collected during several surveys between 1991 and 2012 at two Geological Survey of Canada (GSC) monitoring sites (Border site and Komakuk site) were analysed to provide higher temporal resolution of coastal change for the last two decades. Additionally, the field survey data enabled an assessment to be made of the contribution of geomorphic variables (i.e. beach slope, beach width, cliff slope, absolute cliff height, relative cliff height) towards explaining changes of coastal erosion. According to the findings, the mean annual erosion along the western Yukon coast has been -1.2 ± 0.4 m/a over the entire period of study, with the rates decreasing through time from -1.4 ± 0.6 m/a between 1951 and 1972, to -1.2 ± 0.5 m/a between 1972 and 2009. However, site specific investigations show that there are differences in the mean erosion rates and in temporal trends. To the west at the Border site, the mean annual erosion rate is -1.3 ± 0.3 m/a, and the rates have recently accelerated, while at Komakuk in the east of the study area, the mean annual erosion rate is -0.9 ± 0.2 m/a, with the rates decelerating over time. A comparison of these findings to erosion rates from the Alaskan Beaufort Sea coast indicates that there is a general spatial pattern of decreasing erosion rates from the west to the east. The quantified erosion rates also enabled the calculation of mean annual land loss between 1951 and 2009, which amounted to 4.5 ha/a. An analysis of the influence of shore profile parameters on mean annual erosion rates showed a statistically significant correlation between beach widths and erosion rates (r=0.84) at the Border site. There is also a strong but insignificant correlation between absolute cliff heights and erosion rates at the Border, but no correlations of shore profile parameters with erosion could be distinguished for the Komakuk site.
Summary(Plain Language Summary, not published)
The western Yukon coast contains high amounts of ground ice, faces the direction of most effective storms, and is highly sensitive to climate change. For this reason, temporal and spatial coastal change has been quantified to gain insight into regional coastal dynamics. Aerial photography from 35 km of coastline between Komakuk and the Yukon-Alaska border were analysed to determine rates of coastal change for the time period between 1951 and 2012. The mean annual erosion along the western Yukon coast has been approximately -1.2±0.4 m/a, representing a loss of 4.5 ha/a since 1951 with a volume of 250,000 m3/a. Mean erosion rates have been decreasing in the east at Komakuk, though with a slight increase over the last few decades, while they have been increasing in the west at the border site. Erosion rates are correlated with beach widths and cliff heights at the border, but not at Komakuk. These differences suggest that these two sites are responding differently to similar forcing.