Abstract
Arctic coastal infrastructure and cultural and archeological sites are increasingly vulnerable to erosion and flooding due to amplified warming of the Arctic, sea level rise, lengthening of open water periods, and a predicted increase in frequency of major storms. Mitigating these hazards necessitates decision-making tools at an appropriate scale. The objectives of this paper are to provide such a tool by assessing potential erosion and flood hazards at Herschel Island, a UNESCO World Heritage candidate site. This study focused on Simpson Point and the adjacent coastal sections because of their archeological, historical, and cultural significance. Shoreline movement was analyzed using the Digital Shoreline Analysis System (DSAS) after digitizing shorelines from 1952, 1970, 2000, and 2011. For purposes of this analysis, the coast was divided in seven coastal reaches (CRs) reflecting different morphologies and/or exposures. Using linear regression rates obtained from these data, projections of shoreline position were made for 20 and 50 years into the future. Flood hazard was assessed using a least cost path analysis based on a high-resolution light detection and ranging (LiDAR) dataset and current Intergovernmental Panel on Climate Change sea level estimates. Widespread erosion characterizes the study area. The rate of shoreline movement in different periods of the study ranges from −5.5 to 2.7 m·a−1 (mean −0.6 m·a−1). Mean coastal retreat decreased from −0.6 m·a−1 to −0.5 m·a−1, for 1952–1970 and 1970–2000, respectively, and increased to −1.3 m·a−1 in the period 2000–2011. Ice-rich coastal sections most exposed to wave attack exhibited the highest rates of coastal retreat. The geohazard map combines shoreline projections and flood hazard analyses to show that most of the spit area has extreme or very high flood hazard potential, and some buildings are vulnerable to coastal erosion. This study demonstrates that transgressive forcing may provide ample sediment for the expansion of depositional landforms, while growing more susceptible to overwash and flooding.
Highlights
Continuing sea level rise (SLR) and the declining extent and duration of sea ice and landfast ice render Arctic coasts increasingly vulnerable to coastal erosion, a region where warming exceeds the global mean (Hartmann et al 2013; Serreze and Barry 2011)
We present an assessment of sea level rise, shoreline recession, and flooding on Simpson Point (Fig. 1), a gravelly spit on Herschel Island, Yukon Territory, Canada
Topographic information and scenarios of coastal flooding, we present a map of coastal geohazards
Summary
Continuing sea level rise (SLR) and the declining extent and duration of sea ice and landfast ice render Arctic coasts increasingly vulnerable to coastal erosion, a region where warming exceeds the global mean (Hartmann et al 2013; Serreze and Barry 2011). All these facts present mitigation challenges since these natural processes (e.g., erosion) infringe on a site of human activity and present a serious hazard. Shoreline recession hazards to coastal settlements (Forbes 2011; Mackay 1986; Maslakov and Kraev 2014; Mason et al 2012) and archeological sites (Friesen and Arnold 2008; Westley et al 2011) have been documented across the Arctic. We present an assessment of sea level rise, shoreline recession, and flooding on Simpson Point (Fig. 1), a gravelly spit on Herschel Island, Yukon Territory, Canada. Topographic information and scenarios of coastal flooding, we present a map of coastal geohazards
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