Variability of Arctic coastal erosion along the western Yukon coast

Arctic coastal erosion can have substantial impacts on coastal infrastructure, sometimes prompting the need for aggressive adaptation strategies. It can also induce the release of large quantities of organic carbon and nutrients directly into the nearshore with potential impacts on the ecosystem and/or transformation into greenhouse gases upon contact with sea water. The recent major changes in summer sea ice extent, as well as the warming of sea temperature could potentially lead to greater erosion rates and amplify these processes, yet few studies have quantified erosion in the Canadian Arctic over the period including the 2007 and 2012 minima in sea ice. In this study, we present erosion rates for the western Yukon coast, a 35 km long stretch between the Komakuk Beach Distant Early Warning Line station in the east and the Canada-USA border in the west. Shoreline position data from 44 aerial photographs as well as a SPOT image were analyzed to determine rates spanning 58 years (1951-2009). These remote sensing data were analyzed with the Digital Shoreline Analysis System (DSAS) extension for ESRI ArcGIS. Additionally, total station and real time kinematic global positioning system survey data from coastal monitoring sites maintained by the Geological Survey of Canada at Komakuk Beach and at the border were used to compute rates for the time period between 1991 and 2012. These two datasets together with LiDAR (Light Detection And Ranging) data collected in 2012 and 2013 allowed us to measure shoreline evolution and total volumetric land loss over the past 61 years. Mean annual volumetric land loss for the whole coastal stretch between 1951 and 2009 was calculated to be 250,000 m3/a. DSAS results show rates of coastal erosion in the region have not changed significantly over time. A comparison of the mean annual erosion from 1951 to 1972 to the time period of 1972 to 2009 shows a slight deceleration from 1.4 m/a to 1.2 m/a. A clearer trend towards decreasing erosion was distinguished at the Komakuk Beach study site, where mean annual erosion decelerated from 1.92 m/a to 0.49 m/a during the time from 1951 to 2009. By contrast, coastal erosion at the Canada-USA border increased during the same time period from 1.3 m/a to 1.8 m/a. Work is under way to better understand these local differences and the overall nature of erosion along the Yukon coast