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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.
Erosion and FloodingThreats to Coastal Infrastructure
in the Arctic: A Case Study from Herschel Island, Yukon
Territory, Canada
Boris Radosavljevic
&Hugues Lantuit
&Wayne P ol la rd
&Paul Overduin
Nicole Couture
&Torst e n S a c hs
&Veit Helm
&Michael Fritz
Received: 20 February 2015 /Revised: 9 October 2015 /Accepted: 27 October 2015
#The Author(s) 2015. This article is published with open access at
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 necessi-
tates decision-making tools at an appropriate scale. The objec-
tives 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 anal-
ysis, the coast was divided in seven coastal reaches (CRs)
reflecting different morphologies and/or exposures. Using lin-
ear 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 pathanal-
ysis based on a high-resolution light detection and ranging
(LiDAR) dataset and current Intergovernmental Panel on
Climate Change sea level estimates. Widespread erosion char-
acterizes the study area. The rate of shoreline movement in
different periods of the study ranges from 5.5 to 2.7 m·a
(mean 0.6 m·a
). Mean coastal retreat decreased from
0.6 m·a
to 0.5 m·a
, for 19521970 and 19702000,
respectively, and increased to 1.3 m·a
in the period
20002011. Ice-rich coastal sections most exposed to wave
attack exhibited the highest rates of coastal retreat. The
geohazard map combines shoreline projections and flood haz-
ard analyses to show that most of the spit area has extreme or
very high flood hazard potential, and some buildings are vul-
nerable to coastal erosion. This study demonstrates that trans-
gressive forcing may provide ample sediment for the expan-
sion of depositional landforms, while growing more suscepti-
ble to overwash and flooding.
Keywords Arctic .Coastal erosion .UNESCO .
Vulnerability mapping .Permafrost coasts
Continuing sea level rise (SLR) and the declining extent and
duration of sea ice and landfast ice render Arctic coasts in-
creasingly vulnerable to coastal erosion, a region where
warming exceeds the global mean (Hartmann et al. 2013;
Serreze and Barry 2011). The occurrence of severe storms is
expected to increase, as well (Lambert 2004). Although cir-
cumpolar trends have not been observed (Overduin et al.
2014), multiple studies in the Alaskan Beaufort Sea indicate
that erosion has intensified in recent decades (e.g., Barnhart
et al. 2014a; Jones et al. 2009; Mars and Houseknecht 2007).
Communicated by David Reide Corbett
*Boris Radosavljevic
Research Unit Potsdam, Alfred Wegener Institute, Helmholtz Centre
for Polar and Marine Research, Potsdam, Germany
Institute of Earth and Environmental Science, University of Potsdam,
Potsdam, Germany
Department of Geography and Centre for Climate and Global
Change Research, McGill University, Montreal, Canada
Northern Canada Division, Geological Survey of Canada,
Ottawa, Canada
GFZ German Research Centre for Geosciences, Potsdam, Germany
Alfred Wegener Institute for Polar and Marine Research, Helmholtz
Centre for Polar and Marine Research, Bremerhaven, Germany
Estuaries and Coasts
DOI 10.1007/s12237-015-0046-0
All these facts present mitigation challenges since these natu-
ral 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. In this study, 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. Using shoreline retreat rates, topo-
graphic information and scenarios of coastal flooding, we
present a map of coastal geohazards.
An inherent characteristic of the global climate sys-
tem is the disproportionately high temperature variabili-
ty in the Arctic compared to lower latitudes; a
phenomenon known as Arctic amplification. This phe-
nomenon is documented in instrumental and paleocli-
matic records and in climate model projections
(Serreze and Barry 2011). As a result of the increase
in mean sea surface temperature in the Arctic Ocean,
the melt season lengthened by 5 days per decade from
period, the decline in sea ice extent and thickness ac-
celerated (Kwok and Rothrock 2009; Stroeve et al.
2007,2014,2012) The increasing open water area and
duration dramatically influence wave climates, which
together with greater storm frequency and magnitude
allow for larger waves to develop and generally result
in higher energy coastal systems (Church et al. 2013;
Thomson and Rogers 2014). When coupled with the
10 m
10 m
20 m
20 m
gravelly beach high bluffslow bluffs
30 m
20 m
40 m
high bluffs
Herschel Sill
Fig. 1 Herschel Island is located in the southern Beaufort Sea in Canada. The regional overview shows Herschel Island and bathymetry. The extent of
the study area is shown in the map on the bottom, together with coastline characteristics
Estuaries and Coasts
unique character of permafrost coasts, these conditions
tend to hasten shoreline retreat (Jones et al. 2009;
Manson and Solomon 2007; Overeem et al. 2011).
Coastal evolution in the Arctic is driven by a combination of
relative SLR, factors related to climatic variability, and
morphosedimentary features of the coast (Manson and
Solomon 2007). During the 20th century, mean global sea level
rose at a rate of 1.7 mm·a
, accelerating to 3.2 mm·a
in the
past two decades (Meyssignac and Cazenave 2012). The max-
imum probable rate of SLR in the Canadian Beaufort Sea is
reported at 2.5 mm·a
(Hilletal.1985). At the Tuktoyuktuk
tide gauge, the rate is 3.5 mm·a
(Manson and Solomon 2007);
however, this figure incorporates 1.68 mm·a
of submer-
gence due to glacial isostatic adjustment and correction for
ice-mass changes (James et al. 2014). At Herschel Island,
SLR may be as high as ca. 3 mm·a
(S. Blasco, personal
communication). Projections of mean sea level elevations at
the end of the twenty-first century vary from 0.26 to 0.98 m
(Church et al. 2013). However, due to atmospheric changes and
increases in freshwater input, the rate of relative SLR in the
Arctic is likely to be higher than the global average (Church
et al. 2013). One consequence of SLR is increased occurrence
of coastal flooding (Walsh et al. 2010).
Even though the Arctic coasts are frozen for 9 months of
the year, erosion rates are comparable to lower latitudes, and a
significant proportion of the coasts in the Arctic Coastal
Dynamics Database is erosional (Lantuit et al. 2012).
Growing fetch (length, width, and area), especially when it
is concurrent with storm activity in September and October,
is predicted to generate greater storm surge and wave setup
(Dumas et al. 2005; Thomson and Rogers 2014). Return fre-
quency of flood levels, however, are usually not available as
such data are rarely collected. An analysis of driftwood
strand line elevations at Tuktoyuktuk (ca. 280 km east
of Herschel Island) reports surge elevations of up to
2.4 m above mean water level (Harper et al. 1988), an
area where numerical modeling predicts an amplification
of surge levels (Henry 1975).
The first step in risk mitigation is achieved by defining
vulnerable areas and appropriately managing these areas
(Danard et al. 2003). This study aims to determine how ongo-
ing and projected climatic and sea levelchanges will affect the
historic settlement area on Simpson Point, in particular by
quantifying the hazard potentials related to coastal erosion
and flooding and identifying sites that would potentially be
endangered by these processes. A previous study on Herschel
Island quantified coastal erosion rates (Lantuit and Pollard
2008) but did not consider the shoreline dynamics of
Simpson Point. Maps of SLR sensitivity on a continental scale
exist for the Canadian Arctic (Shaw et al. 1998), and a project
to assess coastal geohazards at a scale of 1:50,000 is under
development (Couture et al. 2013), yet the scale ofthese prod-
ucts limits their value locally. Examples of high-resolution
coastal geohazard maps in Canada and the USA are available
from Northern Newfoundland (Westley et al. 2011)orfrom
the barrier islands of the Texas coast (TAMUCC-HRI 2014).
These maps are valuable tools for coastal decision makers,
and this study provides such an assessment for the historic
settlement area on Simpson Point.
Study Area
The study area encompasses the NE coastal portion of
Herschel Island (69° 36 N; 139° 04 W) (Fig. 1), a stretch
of coast characterized by eroding cliffs, gullies, retrogressive
thaw slump features, an alluvial fan, and a drift-aligned coarse
clastic spit. The geometry of these features has resulted in a
natural harbor named Pauline Cove. The main focus of this
study is Simpson Point, a gravelly spit that forms the eastern
border to Pauline Cove (Figs. 1and 2). Herschel Island is part
of an ice push moraine, formed during the farthest advance of
the Laurentide Ice Sheet to the west during the Wisconsin
Glaciation (Fritz et al. 2012;Mackay1959; Rampton 1982).
It is located in the southern Beaufort Sea, about 2 km off the
mainland coast of the Yukon Territory, Canada. The island
consists of perennially frozen marine and glacigenic sedi-
ments, characterized by rolling topography with a maximum
elevation of 183 m asl (Lantuit and Pollard 2008).
Herschel Island is not permanently inhabited today but re-
mains an important cultural and archeological site as reflected
by its inclusion in the Inuvialuit Final Agreement which was
signed in 1984. Simpson Point is the location of a historic
whaling settlement, as well as many archeological sites.
Whalers arrived in the late 1800s; however, human occupation
of the island began much earlier, with the first Inuvialuit ar-
riving about 800 years ago, while hunters visited the
Fig. 2 Oblique photograph of the historic whaling settlement on
Simpson Point, Herschel Island (photo: W. Pollard, 2007)
Estuaries and Coasts
surrounding areas, and probably Herschel Island, during the
past 10,000 years (Nagy 2012,p.146).Theislandisanim-
portant cultural site for the Inuvialuit and draws many tourists
and scientists to this location. Since 1987, Herschel Island has
been a Yukon Territorial Park jointly managed by the Yukon
Government and the Inuvialuit. In recognition of its
archeological, cultural, esthetic, and biological value,
Herschel Island is a candidate for a UNESCO World
Heritage site (UNESCO 2013). Coastal changes in the
Arctic often threaten coastal infrastructure (Mackay 1986;
Mason et al. 2012). On Herschel Island, coastal erosion has
forced the relocation of buildings (Olynyk 2008,p.212),
while a Thule Eskimo dwellingsite was lost to coastal erosion
(Morgan et al. 1983).
For the purposes of this study, the shoreline was subdivided
into different coastal reaches (CRs), reflecting common mor-
phology and/or orientation (Table 1). The dominant coastal
morphology in this study is ice-rich bluffs (2535 m in height)
fronted by a narrow beach (Harper 1990)(CRs1,2,and7).
The bluffs are composed of fine-grained diamicton and char-
acterized by widespread ground ice that reaches up to 60
70 % by volume in the upper 1015 m (Pollard 1990).
These ice bodies exhibit thicknesses ranging from 4 to 20 m
(Fritz et al. 2011; Pollard 1990). These coastal sections exhibit
landscape features indicative of high ground ice contents, i.e.,
retrogressive thaw slumps (Pollard 2005). The bluffs are sub-
ject to gullying resulting from thawing of exposed permafrost
(thermo-denudation), while CR1 is also undergoing creep or
solifluction-related subsidence expressed in faulting with an
approximate NW-SE strike. Consequently, the drainage areas
for gullies discharging at the foot of the cliff is larger, and the
gullies, wider. CRs 1, 2, and 7 are also subject tocliff collapse
(Fig. 3b), caused by thermoabrasional notching of the cliff
base through the combined action of thermal and mechanical
energy of the sea (Aré 1988; Günther et al. 2013). The alluvial
fan (CR3) is composed of an upward fining sequence of grav-
el, sand, and silt, up to 8 m in thickness (Bouchard 1974). The
mean elevation of CR3 is 3.1 m, with ice contributing up to
40 % to the volume (Obu et al. accepted). Wetland vegetation
on the alluvial fan reflects high soil moisture (Smith et al.
1989); standing and flowing water have been observed.
Block failure has also been observed along the alluvial fan
shoreline (Fig. 3a). At Simpson Point, a large spit progrades
from the southern edge of the alluvial fan. It is composed of
coarse clastic sediments, is about 870 m long, and covers an
area of 15 ha (CR45). Our data indicate that spit elevations
do not exceed 1.2 m above sea level (asl), while mean eleva-
tions of CRs 4 and 5 are 0.4 and 0.3 m, respectively. No
ground ice is reported in the upper meter of soil (Obu et al.
accepted). The spit topography is marked by low ice-push
ridges and storm berms, with remnant shorelines delineating
the progradation of the spit. Westerly longshore drift initially
formed an offshore bar which evolved into a cuspate foreland
and gradually grew into the modern spit (Smith et al. 1989).
The spit is a dynamic feature, its stability fundamentally a
function of sea level change, wave climate, and sediment sup-
ply (Carter and Orford 1993;Forbesetal.1995). Periods of
stability may be punctuated by extreme events that significant-
ly alter the morphology of the spit and transport sediment in
the cross-shore direction. Although vertical accretion of the
barrier caused by overwash may make it less susceptible to
flooding and SLR, such events may be disastrous for anthro-
pogenic features on the spit. CR6 entails the low-lying beach
at the head of Pauline Cove, with a mean elevation of 0.7 m.
Ground ice does not comprise a significant component of the
beach sediments, as was the case in the adjacent spit.
The Arctic climate at Herschel Island is characterized by
long, cold winters and relatively short summers. Weather data
were collected at Herschel Island from 1899 to 1905, while an
automatic weather station was installed in 1995 (Burn and
Zhang 2009). The mean annual air temperature and precipita-
tion are approximately 12 °C and 155 mm, respectively,
based on Environment Canada records for Komakuk Beach
(ca. 50 km west of Simpson Point). The coldest month is
February with a mean monthly temperature of 24.7 °C
(Burn and Zhang 2009). Winds profoundly affect nearshore
dynamics, influencing waves, astronomical tides, nearshore
currents, and ice processes. The presence of seasonal ice limits
the wave energy in this area. Open water conditions typically
occur from June to early October when fetches often exceed
100 km (Héquette and Barnes 1990;Solomon2005). During
the 2009 to 2012 open water seasons, prevailing winds were
typically from the SSE, reaching maximum average hourly
speeds of 46 km h
at Herschel Island (mean 18.7, standard
deviation 8.3) (Environment Canada, Dominant NW winds reached maximum hourly
Tabl e 1 Coastline reach characteristics
Reach 1 2 3 4 5 6 7
Landform High bluffs High bluffs Low tundra bluffs, alluvial fan Barrier spit Barrier spit Beach High bluffs
Material Diamicton Diamicton Silt, sand, gravel Sand, gravel Sand, gravel Sand, gravel Diamicton
Shoreline length (m) 1848 1240 846 711 340 637 895
Orientation ENE S SSE S NNW W SSW
Estuaries and Coasts
speeds of 67 km h
(mean 19.8, standard deviation 10.9)
(Fig. 4). Storms become more frequent in late August and
September and are from the NW and to a lesser extent from
the SSE (Solomon 2005). In the Beaufort Sea, fetch length
may exceed 1000 km in September (Thomson and Rogers
2014), and significant wave heights may exceed 4 m, with
wave periods up to 10 s (Pinchin et al. 1985). Herschel Sill,
a submerged linear feature with a SE strike extends from
Collinson Head to Kay Point on the mainland, serves as a
node for landfast ice formation (i.e., Thetis Bay is covered
by landfast ice during winter)..
The Beaufort Sea is microtidal (0.30.5 m); however,
winds are an important factor in modulating the astronomical
tide (Héquette et al. 1995; Héquette and Barnes 1990).
Northwesterly winds create a positive surge, in contrast to
easterly winds which cause a negative surge.
Shoreline Mapping and Analysis
Given the remoteness of the study area, there is limited avail-
ability of high-quality vertical aerial photographs needed to
extract past shorelines. Consequently, shoreline dynamics
were assessed by digitizing shoreline positions using sets of
22.9 × 22.9 cm (9 × 9 inch) aerial photographs taken in 1952
and 1970, and satellite images from 2000 and 2011. Digital
copies of the historic imagery were scanned by the Canadian
National Air Photo Library (NAPL) at 1500 dpi. Information
about scale and resolution of imagery used for this study is
listed in Table 2.
The images were processed using a softcopy photogram-
metric method with PCI Orthoengine and co-registered to the
2011 image and a 2-m digital elevation model (DEM) based
on Ikonos stereo couples from 2004 to reduce distortion from
lens, camera attitude, Earth curvature, and terrain relief. The
2011 image was registered using differential global position-
ing system (DGPS)-surveyed ground control points as report-
ed in Lantuit and Pollard (2008). All images were
orthorectified assuming a flat terrain, which would lead to
minimal distortion of the image at sea level. Depending on
the image quality and definition, shorelines were mapped to
the wet-dry line at a scale of 1:600.
Shoreline position statistics were calculated with the USGS
Digital Shoreline Analysis System (DSAS) extension for
ESRI ArcGIS (Thieler et al. 2009), using shore normal tran-
sects at 5 m spacing. The more dynamic areas corresponding
to the prograding spit ends were excluded from this analysis,
we did, however, assess the changes in length by casting a
transect across the western tip of the spit. DSAS is capable
of producing various shoreline movement statistics while ac-
counting for uncertainty in the analysis to provide sta-
tistical robustness (Thieler et al. 2009). Sources of
shoreline uncertainty may include pixel, digitization,
rectification, seasonal, and tidal fluctuation errors
(Romine et al. 2009). This study addressed pixel, digi-
tizing, and rectification errors (see Table 2).
The pixel error refers to the spatial resolution of an image.
This corresponds to the image resolution in digital
Fig. 3 Block failure on the
alluvial fan shoreline in CR3 (a),
and steep bluffs exhibiting block
failures characteristic of CRs 1, 2,
>10 - 20
>20 - 30
Wind Speed
Fig. 4 Wind direction and speed frequency in the ice-free period (June
September), observed at the weather station on Simpson Point, Herschel
Island, from 2009 to 2012
Estuaries and Coasts
photographs. The resolution, or sharpness, of aerial photo-
graphs is a combined function of the film and the camera lens.
The resolution is usually determined by photographing a tar-
get containing a test pattern of line pairs (lp) of equal width
and separation. This information was not provided by the
NAPL. However, a typical aerial photogrammetric camera
with a 9 × 9-in. format is capable of resolving 2040 lp per
millimeter, and the ground resolution (GR) can be determined
using Eq. 1(Lo et al. 2007, pp. 291292).
GR ¼wSF ð1Þ
where wis the width in millimeters of one line pair and SF is
the scale factor of the photograph. The worst case estimate
was used to assess the pixel error of the aerial photographs
in this study and ranged between 0.5 and 3.5 m.
Uncertainty of a shoreline position stemming from inter-
pretation istermed digitizing error. In particular, it refers to the
standard deviation of shoreline position interpreted by differ-
ent analysts. In this study, a single operator digitized each
shoreline three times. Intersects of these shorelines were
derived from perpendicular transects at 1 m spacing. A
midpoint was calculated at each transect from which a
mean shoreline was constructed for further analysis. The
mean distance of the constructed midline to the transect
intersects was calculated for every 50-m section of
shoreline. The corresponding digitizing error ranged
from 0 to 3.8 m, with the greatest offsets corresponding
to shorelines obscured by cliff shadows.
PCI Orthoengine reports the quality of the math models
used in the rectification process as a root mean square
(RMS) of the residual. Rectification error in this project was
generally <3.0 m.
DSAS provides a number of different shoreline sta-
tistics (e.g., end point rate (EPR), linear regression rate
(LRR), weighed linear regression (WLR)). Shoreline re-
treat rates in this study are given in EPR for compari-
son between time steps and as LRR for the whole time
period of the study. Negative rates correspond to land-
ward movement of the shoreline, i.e., erosion. EPR is
calculated by taking the distance from the oldest to the
most recent shoreline divided by the elapsed time
(Thieler et al. 2009),asshowninEq.2.
EPR ¼distance in meters
time between oldest and most recent shoreline
The advantage of the EPR method is that it is relatively
simple. Its limitations are that only two end points are
used; thus, reversals, or magnitude changes, and cyclical
trends in shoreline movement may be missed (Genz
et al. 2007; Thieler et al. 2009). We compared the dif-
ferent statistics with the EPR for the period 19522011
and found that EPRs were consistently more conserva-
tive than other statistics, such as LRR and WLR. This
may be indicative of a magnitude change because EPR
only takes into account the oldest and the most recent
shoreline. Nevertheless, we chose the method as it has
been applied in previous studies in the Canadian
Beaufort Sea (e.g., Lantuit and Pollard 2008; Solomon
2005). Foster and Savage (1989) computed the mini-
mum time between shoreline position to include in their
method of calculating the average long-term rate of
where Tis the time between the first and second
datasets, and E1andE2correspondtouncertaintiesas-
sociated with the respective dataset, and Rdenotes the
rate of shoreline movement. In the course of the analy-
ses, we calculated EPRs for the periods 19521970,
19702000, and 20002011. We compared the EPRs
statistically, eliminating rates of change that were small-
er than the associated uncertainty by solving the above
equation for R.
Long-term shoreline change was assessed using a linear
regression approach. This method uses all available data irre-
spective of trend or accuracy. The method is susceptible to
outlier effects and is sensitive to uneven point distribution or
Tabl e 2 Shoreline uncertainties are a combination of root mean square error (RMS) related to differences in location of ground control points (GCPs),
image quality, and shoreline mapping
Date Images Image type Scale GCPs Georeferencing
RMS (m)
Pixel error
Error (m)
Total shoreline
error (m)
August 28, 1952 1 B/W aerial 1:70 000 8 2.9 3.5 0.7 (0.3) 7.0 (0.3)
August 20, 1970 3 B/W aerial 1:12 000 19 1.7 0.6 0.5 (0.6) 2.7 (0.7)
September 18, 2000 1 Ikonos 15 0.9 1.0 0.8 (0.6) 2.6 (0.6)
August 31, 2011 1 GeoEye Base image 0.5 0.4 (0.3) 0.9 (0.3)
Mean uncertainties are given with standard deviations in parentheses
Estuaries and Coasts
point clusters. Although this method may underestimate the
rate of shoreline movement (Dolan et al. 1991) because the
time step between the last two data points is small, these points
should have a greater influence on the LRR and, thus, reflect
recent conditions more closely. All data points were used in
statistical summaries of the LRR.
Changes in coastal reach area for the time periods analyzed
were assessed by creating polygons delimited by shorelines of
respective time steps in ArcGIS.
Vulnerability Assessment
We present a vulnerability assessment for the historic area of
Simpson Point where hazards are defined as something that
may potentially be dangerous or harmful (Huder 2012). In the
context of coastal hazards, hazards are naturally occur-
ring processes that threaten infrastructure and human
life. Vulnerability refers to the exposure to a specific
hazard (Füssel 2007). For our purposes, we limited the
assessment to hazards stemming from shoreline change
and coastal flooding.
In order to assess the vulnerability of Simpson Point to
shoreline retreat, we used the linear regression rates (LRR)
for the period of 19522011 and projected those rates along
the same transects they originated from and where they
crossed the 2011 shoreline, 20 and 50 years into the future,
respectively. The projection time frames match the time
frames used in the flooding hazard assessment discussed later
in this section. The LRR was chosen over other shoreline
movement calculations because all shoreline positions are
considered in the calculation, and more weight is given to
more recent shorelines due to a smaller time increment.
Coastal flooding vulnerability was assessed using the cost
distance analysis tool in ArcGIS. A cost distance analysis
calculates the distance of each cell on a cost surface to the
input source. Input sources were defined using the shoreline
and elevation data. Cost is analogous to the difficulty of water
reaching a certain point on the spit in case of flooding. A cost
surface was created from an airborne light detection and rang-
ing (LiDAR) digital elevation model and a derived slope ras-
ter. LiDAR data were obtained in 2013 during an overflight of
the Alfred Wegener Institute Polar 5 research aircraft using a
RIEGL VQ-580. These data have a point spacing of <1 m.
Low-pass filtering was used to remove spikes in LiDAR data.
This dataset was gridded to a 1-m resolution. We used a stan-
dard normal deviate approach to normalize differences in
magnitude between the elevation and slope datasets. Equal
weighing was given to both elevation and slope. The cost
distance analysis allows different weights to be attached to
input sources. The sea was defined by the 2011 shoreline
and weighed at 1, while areas defined by the 0 m contour
located on the spit defined sources weighed at 0.5. The
internal sources were deemed necessary because the spit is
composed of gravelly sands with high hydraulic conductivity.
The resulting cost distance raster was classified based
on projections of sea level rise in 20 and 50 years,
based on representative concentration pathways (RCPs)
2.6 and 8.5 (Church et al. 2013). These represent low-
and high-end estimates of global sea level rise made by
the Intergovernmental Panel on Climate Change (IPCC).
In 2031, the RCP projections of sea level are very sim-
ilar (0.39 ± 0.03 and 0.4 ± 0.04 m, respectively), while
in 2061, sea level for RCP2.6 and RCP8.5 is at
0.53 ± 0.08 and 0.6 ± 0.11 m, respectively. There is
no tide gauge and thus no established sea level at
Herschel Island. Sea level elevation was derived from
the LiDAR data, as no anomalous water level was ob-
served in the field. Based on the RCPs, we created
polygons with elevation ranges that defined different
hazard typologies and classified the cost distance raster
in Exelis ENVI:
1. Extreme: elevation range 00.36 m. Areas subject to
very frequent flooding, for water levels up to the
lower RCP estimate
2. High: elevation range 0.360.45 m. Areas subject to fre-
quent flooding, incorporating the range of sea level pro-
jections by RCP2.6 and RCP 8.5 in 2031
3. Moderate: elevation range 0.450.71 m. Areas subject to
flooding with water levels matching the range of RCP2.6
and RCP8.5 sea level projections in 2061
4. Low: elevations above 0.71 m. Areas subject to
flooding with water levels exceeding the 50-year
sea level projection
Shoreline Movement
Shorelines were digitized and EPRs were calculated using
shorelines from 1952, 1970, 2000, and 2011 (Fig. 5).
Uncertainties were accounted for, as summarized in Table 2.
Negative values in this study indicate landward movement of
the shoreline, i.e., erosion and positive values seaward shore-
line advance. After eliminating shoreline movement rates
smaller than the minimum (Eq. 3), we compared EPRs for
different time periods statistically (Table 3and Fig. 6). The
data show erosion in almost all CRs across all time periods. A
significant deceleration of erosion between 1952 and 1970
and 19702000 using a paired ttest (t=9.54, df = 776, p
value =0). Erosion significantly increased between 1970 and
2000 and 20002011 (t= 22.37, df = 934, pvalue =0). We
noted significant landscape changes including reactivation of
Estuaries and Coasts
retrogressive thaw slumps and gullies and drainage of polyg-
onal wetlands in the 1970s imagery. In total, a net loss of ca.
31.1 ha of coastal area loss occurred over the time period of
the study, a mean loss of 0.53 ha·a
CR1 lies to the north of Collinson Head, where exposure
to coastal processes is highest. Overall, this section is char-
acterized by erosion and underwent the most rapid mean
retreat in the period 19521970 or 2.1 ± 0.4 m·a
Overall, erosion was fairly uniform spatially (Fig. 6), with
the highest erosion rates (3.0 m·a
or more) occurring
close to the bend where a large gully drains some polygonal
wetlands and thermokarst inland and decreasing further SW.
In the period 19702000, a deceleration of retreat took place,
with a mean retreat rate of 1.2 ± 0.5 m·a
20002011 to 1.8 ± 0.6 m·a
. Over the period of the study
(19522011), the shoreline retreated 91.9 ± 21.7 m, on av-
erage, with the greatest erosion rates and area loss (ca. 18 ha)
affecting the bend of the headland (Fig. 6).
CR2 is somewhat less exposed to wave attack gener-
ated by predominant NW winds, given its orientation to
the south and the presence of the Herschel Sill (Fig. 1).
In the period of 19521970, mean retreat of
0.9 ± 0.4 m·a
was followed by 0.8±0.5m·a
(19702000), accelerating to 1.0 ± 0.5 m·a
20002011. The greatest shoreline retreat occurred in
the eastern portion of CR2, gradually decreasing to the
west (Fig. 6). The westernmost part of CR2 is marked
by deeply incised gullies. In addition, a large
Tabl e 3 Summary of shoreline change in terms of end point rates (EPR) and area. The linear regression rate (LRR) of shoreline change (m·a
different time periods and coastal reaches. Long-term shoreline movement is given as a linear regression rate (LRR) that includes all time steps
CR 15921970 19702000 20002011 19522011
EPR mean
EPR range
EPR mean
EPR range
EPR mean
EPR range
LRR mean
LRR range
12.1 ± 0.4 3.4 to 1.3 7.34 1.2 ± 0.5 2.5 to 0.2 2.01 1.8 ± 0.6 3.4 to 0.2 3.58 1.5 ± 0.4 2.2 to 0.8 17.60
20.9 ± 0.4 2.1 to 0.4 1.33 0.8 ± 0.5 2.0 to 0.1 3.07 1.0 ± 0.5 3.5 to 0.3 1.41 0.8 ± 0.5 1.9 to 0.2 5.76
31.4 ± 0.6 2.1 to 0.4 1.49 1.7 ± 0.7 2.5 to 0.1 3.65 4.0 ± 1.1 5.5 to 1.0 2.85 1.8 ± 0.7 2.5 to 0.4 7.99
.2±1.2 2.3 to 1.7 1.16 0.9 ± 0.8 0.1 to 2.7 1.84 1.7 ± 1.7 3.9 to 1.3 1.28 0.4 ± 0.5 0.4 to 1.1 0.83
50.1 ± 0.7 0.7 to 1.6 0.03 0.3 ± 0.1 0.5 to 0.2 0.23 0.1 ± 0.5 0.7 to 0.7 0.03 0.2 ± 0.2 0.4 to 0.5 0.29
60.5 ± 0.1 0.6 to 0.4 0.20 0.3 ± 0.2 0.7 to 0.1 0.02 0.3 ± 0.1 0.5 to 0.3 0.12 0.1 ± 0.2 0.5 to 0.1 0.37
7 0.6 ± 0.2 0.4 to 1.2 0.38 0.1 ± 0.2 0.3 to 0.3 0.03 0.3 ± 0.1 0.6 to 0.3 0.17 0 ± 0.1 0.1 to 0.1 0.11
All 0.6 ± 0.5 3.4 to 1.7 11.16 0.5 ± 0.4 2.5 to 2.7 7.06 1.3 ± 0.7 5.5 to 1.3 6.88 0.6 ± 0.3 2.5 to 1.1 31.07
Extremes are in bold type
Fig. 5 a Study area showing
historic shoreline positions and
different coastal reaches (CR1-7).
CRs differ in morphology and
location and are numbered 17. b
Rates for different time periods.
Colored bars at the top of the
graph indicate the rate exceeded
the minimum requirement for
statistical treatment
Estuaries and Coasts
thermokarst feature, as well as a number of smaller
ones, was active in the 1970 imagery. These features
were eroded or enlarged in the 2000 and 2011 imagery.
CR2 underwent ubiquitous retreat over the period of the
study, with an area loss of 5.8 ha. The only excursions
of the shoreline were caused by mud lobes deposited by
gully streams at the base of the cliffs or by block fail-
ure of the cliffs.
CR3 encompasses the alluvial fan shoreline. This section of
coast underwent the most extensive erosion over the period of
the study. Overall, the shoreline retreated up to 152.7 or
108.7 ± 26.1 m on average over the study period, culminating
in a net area change of almost 8 ha. Erosion rates consistently
increased from 1.4±0.6to1.7±0.7to4.0±1.1m·a
periods 19521970, 19702000, and 20002011, respectively.
The highest mean retreat of this study occurred in CR4 in the
period of 20002011, retreat rates reaching 5.5 m·a
Spatially, the greatest retreat occurred in the western portion
in 19521970, at the transition of cliff and alluvial fan, and
decreasedtothewestandeast(Fig.6a). The erosional hotspot
migrated west in the following periods. In 19702000, the area
loss was spread over a wider area, with the greatest retreat in the
central portion. In 20002011, erosion was highest in the cen-
tral and eastern portions of CR3, decreasing to the east, and less
to the west, as CR4 experienced drastic shoreline advance.
CRs 45 represent the exposed and protected shorelines of
Simpson Point. These coastal sections underwent the most
complex changes. The western spit terminus advanced
62.7 m from 1952 to 1970 (3.5 m·a
), another 130.6 m
(4.3 m·a
) from 1970 to 2000 (Fig. 5b). The spit morphology
in 2000 suggests recent breaching of the spit and its highly
dynamic non-linear nature. In the period of 20002011, the
spit retreated 54.7 m (5.0 m·a
). These changes profoundly
affected shoreline dynamics in CRs 4 and 5. The shoreline in
CR4 rapidly prograded in the periods of 19521970 and1970
2000 with mean EPRs of 0.2 ± 1.2 and 0.9 ± 0.8 m·a
spectively. However, both advance and retreat occurred in
these time periods, although advance dominated in 1970
2000 and 20002011, expressed in net area gains of 1.84
and 1.28 ha, respectively. The eastern portion of CR4 experi-
enced some of the most rapid retreat recorded in this study (<
3.9 m·a
1) in 20002011 that offset modest accretion in the
westernportionresulting in a mean shoreline change of
1.7 ± 1.7 m·a
. The spit shoreline advances west of an
inflection point located approximately at the center of CR4,
while erosion prevails to the east.
In CR5, two inflection points delimit regions of accretion,
with erosion occurring in between. The erosional hotspot
followed the extension of the spit to the west. CR5 is charac-
terized by modest retreat in all time periods of the study rang-
ing from 0.3 to 0.1 m·a
(Table 3, Fig. 6b), also reflected in
net area loss across all time periods; however, western and
eastern portions of CR5 have advanced moderately over the
period of the study. The storehouses located approximately in
the middle ofCR5 are located in the part of CR5 with the most
rapid retreat.
Mapping the shoreline on the beach corresponding to CR6
was challenging. Image contrast, typically clear water and a
gentle rise of the foreshore, complicated the identification of
the wet-dry line. The results indicate CR6 is largely retreating,
with rates ranging from 0.5 to 0.3 m·a
The shoreline position in CR7 underwent little change over
the time period. Mass movements and gully deposition at the
base of the coastal bluffs mask coastal retreat. This draws
attention to a potentially unique aspect of permafrost coasts
linked to backshore and onshore changes in permafrost
Fig. 6 a Spatial distribution of
EPRs shown as transects used in
the analysis clipped to the extent
of shoreline change and classified
according to the rate of change. b
Boxplots showing shoreline
retreat within coastal reaches for
different time periods. The end
point rates (EPR) indicate rates
between two time periods, while
the linear regression rate (LRR)
includes all time periods in the
Estuaries and Coasts
conditions triggered by coastal retreat. Since the period of
19501970, CR7 has been undergoing accelerating retreat,
with rates approximately 0.3 m·a
Retreat rates calculated using the linear regression method
incorporating shoreline positions from all time periods of the
study are typically more conservative than EPRs from 1970 to
2000 and 20002011.
Hazard Assessment
The cost distance analysis produced a map which indicates
that the most of the spit area has an extremely high flooding
potential, with a significantly lower portion of the area classi-
fied with high and moderate potentials (Fig. 7). There are no
areas located on the spit where the flooding potential was
ranked as low. The classes were defined based on IPCC pro-
jections of sea level rise for years 2031 and 2061, while ele-
flooding hazard potential, incorporated elevations below the
IPCC estimates to the target dates. The map is annotated to
indicate highly dynamic areas and the location of a likely
washover path. These areas should be considered highly haz-
ardous by default. Using the LRR in CR4 and CR5, shoreline
positions were projected for years 2031 and 2061, 20 and
50 years into the future, respectively.
Shoreline Dynamics
A comparison of mean shoreline movement within CRs
across the time periods studied (Fig. 6b) reveals two main
patterns: CR1, CR2, CR4, and CR6 experienced intense ero-
sion in the 19521970 period, decreasing in the period of
19702000, to significantly increase in the period of 2000
2011. A steady and statistically significant acceleration, albeit
of different magnitude, took place in CR3 and CR7. In
general, a significant acceleration of coastal retreat took place
in all coastal reaches in the period 20002011, with the ex-
ception of CR5 (Figs. 5b and 6b). Spatial patterns are also
apparent where shorelines in protected coastal sections (CRs
57) changed little, while the shoreline in exposed coastal
reaches retreated drastically (Fig. 6a). The spit shorelines were
most dynamic, especially the south-oriented shore (CR4).
Temporal trends follow the previous study by Lantuit and
Pollard (2008), who found that the mean rate ofcoastal retreat
in 19521970 decreased in comparison with 19702000. A
direct comparison of current erosion rates with the aforemen-
tioned study is confounded because the respective studies
have a different spatial extent and resolution. In contrast to
the previousstudy, our study employed a 5-m transect spacing
(versus 300 m), investigated a smaller area, and included the
shorelines of Simpson Point and the adjacent alluvial fan
(CR3). In contrast to other shoreline sections, the rate of re-
treat increased across all time periods for CR3. Nevertheless,
retreat rates and erosional trends presented by this study are
generally in agreement with similar studies from the region
(Héquette and Barnes 1990; Lantuit and Pollard 2003,2008;
Solomon 2005). Clearly, the inclusion of coastline sections
not addressed in the previous study presents a more detailed
analysis of shoreline change on Herschel Island, echoing pre-
vious research which recognized thatlocal conditions result in
significant spatial variability present within and among differ-
ent reaches (Harper 1990; Jones et al. 2009; Solomon 2005).
In the present study, absolute retreat rates among reaches may
vary up to factor 46 and up to factor 25 within reaches in this
study. Spatially dependent morphodynamic factors, such as
the degree of exposure to waves, extreme events and their
return frequency, ice processes, lithology, ice content, and
offshore geological features, may help explain different ero-
sion patterns evident herein.
Héquette and Barnes (1990) attempted to explain coastal
bluff retreat in the Beaufort Sea as a function of different
parameters (e.g., ground ice content, wave energy, sediment
texture, cliff height, shoreface gradient) and found that only
Flooding Potential
Projected Shoreline
0 100 20050
Fig. 7 Coastal geohazard map
indicating flooding potential,
historic, and projected shorelines
and dynamic areas with high
hazard potential. These semi-
transparent layers are
superimposed on the 2011 image.
Locations of buildings and
archeological sites are highlighted
as blue and peach rectangles
Estuaries and Coasts
ice content and wave energy correlated weakly with coastal
retreat. CR1, CR2, CR3, and CR7 constitute ice-rich portions
of the shoreline in the present study. In maps of ground ice
distribution on Herschel Island, Bouchard (1974) indicated
that S, SSE, and SE sections are ice-rich and the NE shore
as not ice-rich. In addition, Pollard (1990)reportedthatlarge
tabular ice bodies characterized the SE-oriented shore, with
ice contents of up to 6070 % by volume in the upper 10
15 m, while exposures on the NE-oriented shoreline were
smaller and less continuous. Far lower ice-contents are sug-
gested by recent data (Fritz et al. 2011). Nevertheless, retro-
gressive thaw slumps are common on SE-oriented coastlines,
features that are characteristic of ice-rich permafrost (Pollard
2005). Lantuit and Pollard (2008) found the greatest erosion
rates on shorelines oriented NW, NNW, and N, as these are
most exposed to storms, which originate in the northwest in
the southern Canadian Beaufort Sea (Hudak and Young
2002); the retreat, however, decelerated in the period 1970
2000 for most shoreline orientations, while a slight accelera-
tion was recorded for shorelines oriented S and SW. The in-
fluence of wave energy, and perhaps ice-content, is evident in
consistently high erosion rates in CR1. This coastal section is
most exposed to NW storms in the current study, and the rate
of coastal retreat decreased by almost half from the 1952
1970 to the 19702000 periods. This trend may be explained
by a decrease in storm activity in the region since 1980
(Lantuit and Pollard 2008 and references therein).
Ice processes acting on the shoreface may also amplify coastal
retreat in CR1. Héquette and Barnes (1990) classify the shoreface
according to geomorphic processes into four zones. The fore-
shore zone at the bluff toe is dominated by thermal and wave
erosion. The nearshore zone up to 6 m depth is dominated by
waves and currents. The upper shoreface from 6 to 9 m depth is
characterized by accretion through ice pileup and ice push-up,
while the lower shoreface is dominated by ice gouging. Ice goug-
ing leads to erosion of the lower shoreface and forces coastal
retreat as the equilibrium profile is disturbed. The highest densi-
ties of ice gouges are found seaward of the landfast ice limit,
which in the Beaufort Sea approximates the 20-m isobath
paralleling the NE shoreline of Herschel Island and extending
along Herschel Sill (Mahoney et al. 2014;Reimnitzetal.1978).
Therefore, the presence of Herschel Sill may shield coastal
reaches west of CR1 from ice gouging. The rate of retreat in
CR2 is typically half the mean rate in CR1 and changed little
from 1952 to 1970 to the 19702000 period, contradicting the
previous study by Lantuit and Pollard (2008). This may be an
artifact of a smaller study area in the current study. Lantuit and
Pollard (2008) found accelerating erosion in S- and SW-oriented
shorelines and explained it in terms of a secondary preferential
direction of storms from the SE and SSE (Harper and Penland
1982) and by the concentration of massive ice along these shore-
lines. The number of retrogressive thaw slumps increased by
61 % from 1952 to 2000 (Lantuit and Pollard 2008). We also
observed similar landscape changes in aerial imagery used in this
study, as mentioned in BShoreline Movement^and indicated by
the shoreline position in Fig. 5a. Thermoabrasion of sediments is
enhanced by the presence of large quantities of massive ground
ice (Kobayashi 1985;Aré1988; Héquette and Barnes 1990).
Furthermore, thaw subsidence of 20 m or more can be induced
by melting of ground ice in a retrogressive slump headwall, while
the overall cohesiveness of sediments is reduced and thus more
easily eroded (Lantuit and Pollard 2008). High and increasing
erosion in CR3 agrees with the previous study and may be ex-
plained in similar terms, taking into account the lower elevation
and absence of massive ice. In CR3, the presence of standing
water, along with active drainage and high ground ice contents,
potentially renders this part of the coast most sensitive to erosion.
Shoreline retreat rates in CR4 exhibited the highest variability
(both within and among all time periods), reflecting the dynamic
nature of the spit and its morphodynamic dependence on the
adjacent CR3. Shoreline stability in CR7 is a function of
denudational processes affecting the hinterland, with accompa-
nying deposition on the bluff toe. A more thorough analysis of
ground ice distribution, nearshore parameters, and a comprehen-
sive analysis of storm climatology should be undertaken to ex-
plain the spatial and temporal variations more accurately.
The acceleration of shoreline change rates found in this
study agrees with results by other studies in the Alaskan
Beaufort Sea (e.g., Barnhart et al. 2014a; Jones et al. 2009;
Mars and Houseknecht 2007). No increase in overall storm
frequency, which could explain these findings, could be iden-
tified by previous studies, although there are no studies that
match the time period in the current study (Hudak and Young
2002). However, storms in the Beaufort Sea are more frequent
in late summer and early fall (Atkinson 2005). In addition,
landfast ice breakup and ice-free conditions in the Beaufort
Sea occurred 19 and 39 days earlier, respectively, in the period
20002007 than in 19731977 (Mahoney et al. 2014).
Duration of wave setup and increased wave height show sig-
nificant positive trends as the length of the open water season
in the Beaufort Sea increased by factor 1.9 from 1979 to 2012
(Barnhart et al. 2014b). The lengthening open water season
resulted in anomalously high surface water temperatures in the
most of the Arctic Ocean including the Beaufort Sea (Steele
et al. 2008), which is another factor that drives erosion of ice-
rich permafrost coasts (Aré 1988; Barnhart et al. 2014a;
Kobayashi et al. 1999; Ravens et al. 2012) and may help
explain the accelerating trend observed by the current study.
These changes result in increasing vulnerability of Arctic
coasts to erosion (Barnhart et al. 2014b).
Coastal Evolution
Our analyses indicate erosion is widespread in the study area.
It is likely that the trends in shoreline dynamics will continue
in the future as well. Based on the LRR for the period 1952
Estuaries and Coasts
2011, we projected the shoreline 20 and 50 years into the
future. The LRR is susceptible to outlier points and clustered
data and was chosen because the time step between the last
two data points is small; therefore, these points should have a
greater influence on the LRR and better reflect recent condi-
tions. All data points were used in statistical summaries of the
LRR. (e.g., Dolan et al. 1991). It must be emphasized, how-
ever, that our analyses are based on the assumption of linearity
of coastal processes, such as SLR and wave intensity. Given
that we found an intensification of coastal erosion over the
period of the study, the projected shorelines represent a very
conservative estimate of future shoreline position, as they are
consistently lower than the EPR from 2000 to 2011, at least
along the shorelines of CRs 14. The assumption of linearity
may not be appropriate given the non-linear predictions of
climate change in the Arctic, including a lengthening of the
open water season duration and sea ice decline, leading to a
positive influence on the wave climate (Church et al. 2013;
Thomson and Rogers 2014) that coincides with the period of
increased storm frequency (Atkinson 2005). As an overall
increase in the frequency of extreme events is expected
(Lambert 2004), and long-term SLR affects the Beaufort Sea
(Manson and Solomon 2007), increasing erosion of the
Beaufort Sea coast is almost certain (Jones et al. 2009;
Manson and Solomon 2007; Overeem et al. 2011).
These changing environmental factors will affect the evo-
lution of Simpson Point, as well. The gravelly spit was rela-
tively stable over the study period, with aggradation in CR4,
modest erosion in CR5, and an increase in overall length. The
excursion of the spit terminus in 2000 probably resulted from
breaching during a storm event and subsequent adjustment.
Ample sediment supply indicated by high updrift erosion rates
allowed the spit to increase in width, with minor retreat of the
spit terminus position in 2000. The inflection point located
roughly in the middle of CR4 seems to originate from a
morphodynamic feedback of spit growth, and at least to some
extent, the different compositions of CR3 and CR4. As
erosion continued to the east, the inflection point mi-
grated west and will likely continue, as the shoreline
adjusts to the changing coastal setting. Sediment supply
does not seem to be a limiting factor for spit growth;
however, changing environmental parameters may in-
crease the frequency of coastal flooding and overwash
(Manson and Solomon 2007; Walsh et al. 2010)and
affect ice processes (e.g., ride-up and push-up).
Ice pileup and push-up are processes of beach nourishment
in Arctic regions (Reimnitz et al. 1990) that are active on
Simpson Point. Ice push-up transports sediments from the
shoreface, depositing them on the beach and creating distinc-
tive pile-up mounds, while ice ride-up refers to the landward
sliding of an ice sheet across the beach. These processes are
active mainly when the sea is frozen or transitions to frozen.
Poorly sorted, semi-linear hummocky melt-lag deposits found
on the spit testify to the effects of these processes. Although
they are commonly reworked by waves, these deposits pro-
vide at least some protection from wave attack and storm
surge. Reimnitz et al. (1990) report that pileups were more
frequent earlier in the century when fetch was shorter, yet it
is unclear how these ice processes will be affected as environ-
mental changes proceed.
Another caveat in the evolution of Simpson Point in light of
ongoing transgressive forcing is the effect of increased coastal
flooding and overwash frequency. Sallenger Asbury (2000)
described four regimes of storm impact on sandy barrier
islands whereby run-up and foredune or berm crest elevation
are the main components. Orford (2011) proposed a similar
impact scale recognizing the distinct morphodynamic charac-
teristics of gravelly barriers. Apart from total barrier inunda-
tion and removal, the morphodynamic process-response is
still not well understood. In a rare example of gravelly beach
dynamics in the Arctic, beaches in the resolute area have
shown some resilience to moderate storms (St-Hilaire-
Gravel et al. 2012). Critical to the morphodynamic response
is the return period of extreme water elevations (Forbes et al.
1995;Matiasetal.2012; Orford and Anthony 2011), which
has been demonstrated on sandy barriers (e.g.,Claudino-Sales
et al. 2008; Morton et al. 1994). Substantial reworking of
sediments is possible when critical stability thresholds are
exceeded, or sediment supply is interrupted (Matias et al.
2012). However, if the sediment supply for Simpson Point is
not interrupted, moderate storms overtopping the barrier crest
may increase the resilience of the barrier as the wave run-up
will act to build up the barrier crest (Matias etal. 2012; Orford
et al. 1991; Orford and Anthony 2011). The low elevations of
Simpson Point, and observed washover deposits, point to the
high potential of overtopping and washover. The eastern por-
tion of CR4, especially, is being eroded quickly toward the
low-lying wetland backbarrier. This area should be considered
as having a high hazard potential of breaching and washover.
However, in the absence of tide data at Simpson Point and
run-up and swash models for the site and the dearth of com-
parative studies in the Arctic, stability thresholds remain a
question for further studies. Ice and overwash processes may
adversely affect the infrastructure on the spit. However, they
are part of the life cycle of an Arctic barrier, allowing for
lateral and vertical accretion as sediments are delivered to
the backshore and the barrier platform.
Geohazard Mapping
In BHazard Assessment,^we presented a map indicating
future shoreline positions and flooding hazard created in
the course of the study. This map identifies infrastruc-
ture or archeological sites likely vulnerable to these haz-
ards (Fig. 7).However,theseanalysesrequireanumber
of considerations.
Estuaries and Coasts
Shoreline projections do not take into account morpholog-
ical changes caused by future storm events that may punctuate
the evolution of the spit. The flooding hazard assessment also
does not consider event-related factors such as wave run-up
levels or storm surge nor does it consider factors that may
impede the propagation of a flood (i.e. surface roughness,
permeability, etc.). Likewise, morphological changes to the
beachface and berm during an event are not considered.
Furthermore, fundamental data, such as surge return period,
the potential for barrier washover, or even the elevation of
mean sea level, are not established at the study site and com-
plicate validation of the presented model. Even though there
are considerable differences in methodology and data quality
with the current study, a recent study employeda similar flood
mapping approach to qualitatively validate a storm impact in
their study area and found good agreement between observed
and predicted impacts (Perini et al. 2015).
The cost distance analysis honors cell connectivity (lateral
and diagonal) (Adriaensen et al. 2003) so that the model is
superior to the Bbathtub^models of inundation, in which con-
tours below a projected sea level were flooded regardless of
connectivity (e.g., Moorhead and Brinson 1995; Titus and
Richman 2001). However, connectivity in our analysis may
overestimate flooding (Poulter and Halpin 2008). Therefore,
our type of geohazard analysis necessitates further improve-
ment in comparison to other coastal geohazard maps (e.g.,
Perini et al. 2015; TAMUCC-HRI 2014). Rather than
predicting impacts of flood events, the map illustrates areas
that could be affected by flood levels matched to current IPCC
estimates of sea level rise. This analysis does provide insight
into the existing hazard potential and can be of use to stake-
holders, archeologists, and park management. The historical
buildings close to the shore on the north side of Simpson Point
are at risk of being undermined by coastal erosion. It is clear,
however, that due to the low elevation, coastal flooding
threatens most of the spit. The areas mapped as having an
extreme flood potential fall below even the 20- and 50-year
estimates of sea level in IPCC RCPs (>0.36 m). SLR and more
frequent extreme events will increase the frequency of
flooding of the spit even further.
The presentstudy investigated shoreline dynamics ofthe east-
ern tip of Herschel Island, with a focus on a gravelly spit,
Simpson Point, where we assessed coastal hazards stemming
from shoreline retreat and coastal flooding. Herschel Island is
a candidate for a UNESCO world heritage site. Our analyses
demonstrate Simpson Point is vulnerable to sea level rise, like
many world heritage sites around the world (Marzeion and
Levermann 2014), although this has previously not been doc-
umented in the Arctic.
Shoreline retreat was assessed based on aerial photographs
for the periods 19521970, 19702000, and 20002011. Our
analyses reveal that the study area is undergoing widespread
shoreline retreat. The mean rate of shoreline movement de-
creased from 0.6 ± 0.5 to 0.5 ± 0.4 m·a
in the periods of
19521970 and 19702000, respectively, increasing to
1.3 ± 0.7 m·a
in the period 20002011. Coastal sections
with the highest wave exposure and ice content had the
highest rates of erosion. Very high retreat rates (up to
4.0 m·a
) affected CR3, an alluvial fan with active
drainage and waterlogged soils. Shoreline movement
on coastal sections located on the coarse clastic spit
showed the highest variability.
We present a map featuring future shoreline positions 20 and
50 years in the future and classified flood hazard potential on a
cost distance surface according to IPCC projections of sea level
rise for the same time periods. The resulting coastal geohazard
indicates that coastal hazards on Simpson Point are less related to
coastal retreat, but flooding, combined with transgressive forcing
and climate change (e.g., increased occurrence of extreme
events), poses serious threats to this site. The findings of this
study may be applicable to similar sites in the Arctic (e.g.,
Shingle Point). The conditions described by our analyses raise
questions regarding risk mitigation. The first step in risk mitiga-
tion is achieved by defining vulnerable areas and appropriately
managing these areas. Hazard reduction measures fall into two
main categories: non-structural and structural measures (Danard
et al. 2003). Non-structural measures include not only relocation
and land use regulation but also soft-armoring approaches such
as beach nourishment. Structural measures include the use of sea
walls, dikes, groins, flood-proofing, and storm surge-resistant
construction. Given the remoteness and associated construction
costs in the study area, many of these options are not viable. A
mitigation strategy, therefore, should include a combination of
these approaches; however, it must be in close consultation with
the Inuvialuit for whom Herschel Island is an important cultural
and historic site. A mitigation strategy should reflect Inuvialuit
attitudes toward land use, burial and spiritual sites, and historical
and cultural sites. For example, grave sites are not to be disturbed,
and nature should be allowed to take its course (Inuuvik
Community Corporation, Tuktuuyaqtuq Community
Corporation, and Aklarvik Community Corporation 2006, pp.
81). Therefore, our recommendation is to relocate and elevate
those historic buildings acutely at risk. Part of the strategy should
include the prioritization of archeological investigations. These
efforts would ensure that the historical and cultural heritage of
Simpson Point is protected and preserved for future generations
compatible with traditional values, even though the spit will ex-
perience increased flooding recurrence.
Acknowledgments We are grateful to the Yukon Territorial Government,
Yukon Parks (Herschel Island Quiqiktaruk Territorial Park), and the Aurora
Research Institute for their support during this project. This work was funded
Estuaries and Coasts
by the Helmholtz Association (grant no. VH-NG-801 to Hugues Lantuit). We
would like to thank Michael Krautblatter, George Tanski, Frank Günther,
Samuel Stettner, Stefanie Weege, and Juliane Wolter for their help in the field
and in the lab; Clara Armaroli, Lee John Meyook, Edward McLeod, and
Richard Gordon for their feedback on the flooding potential map; Laura Elena
Kelvin and Max Friesen for their clarification of Inuvialuit interests; and many
more who made this project possible.
Open Access This article is distributed under the terms of the Creative
Commons Attribution 4.0 International License (http://, which permits unrestricted use,
distribution, and reproduction in any medium, provided you give appro-
priate credit to the original author(s) and the source, provide a link to the
Creative Commons license, and indicate if changes were made.
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Estuaries and Coasts
... Bien qu'il ait été jusqu'à présent possible d'observer et d'étudier de nombreuses ressources patrimoniales côtières partout à travers le monde, une très grande proportion reste encore à identifier, à étudier et à protéger. Quelques études se sont intéressées spécifiquement aux effets des aléas côtiers sur les ressources archéologiques (Fitzpatrick et al. 2006 ;Reeder et al. 2010 ;Wickham-Jones 2010 ;Daire et al. 2012 ;Kane et al. 2012 ;Milner 2012 ;Dawson 2013 ;Westley et McNeary 2014 ;Johnson et al. 2015 ;Radosavljevic et al. 2015 ;Reeder-Myers 2015 ;Pourkerman et al. 2018), plus rarement sur les autres ressources culturelles (Carrasco et al. 2007 ;Maio et al. 2012 ;Pian et Regnauld 2013 ;Radosavljevic et al. 2015 ;Reimann et al. 2018). ...
... Bien qu'il ait été jusqu'à présent possible d'observer et d'étudier de nombreuses ressources patrimoniales côtières partout à travers le monde, une très grande proportion reste encore à identifier, à étudier et à protéger. Quelques études se sont intéressées spécifiquement aux effets des aléas côtiers sur les ressources archéologiques (Fitzpatrick et al. 2006 ;Reeder et al. 2010 ;Wickham-Jones 2010 ;Daire et al. 2012 ;Kane et al. 2012 ;Milner 2012 ;Dawson 2013 ;Westley et McNeary 2014 ;Johnson et al. 2015 ;Radosavljevic et al. 2015 ;Reeder-Myers 2015 ;Pourkerman et al. 2018), plus rarement sur les autres ressources culturelles (Carrasco et al. 2007 ;Maio et al. 2012 ;Pian et Regnauld 2013 ;Radosavljevic et al. 2015 ;Reimann et al. 2018). ...
... Deux approches complémentaires ont été adoptées pour connaître l'ampleur des effets des aléas côtiers sur le patrimoine archéologique. La première a été de constater l'état des sites archéologiques côtiers inventoriés dans les zones à risque, la méthodologie la plus couramment utilisée (Reeder et al. 2010 ;Daire et al. 2012 ;Kane et al. 2012 ;Westley et McNeary 2014 ;Johnson et al. 2015 ;Radosavljevic et al. 2015). La seconde, moins fréquente (Fitzpatrick et al. 2006 ;Dawson 2013), a été d'évaluer le potentiel archéologique de secteurs exposés aux aléas côtiers. ...
... been observing many of these changes for decades (Ford et al. 2018;Simonee et al. 2021 When permafrost thaws, the soil, gravel, and sand that was once frozen solid can start to shift, slump, and slide (Radosavljevic et al. 2016;AMAP 2019). This can significantly damage roads, buildings, airports, and other infrastructure, which were often built on the permafrost as a natural foundation. ...
... More information about flood costs across the North can be found In the Institute's Under Water report (Figure 12). Floods and sea level rise could damage housing, which is already in short supply in many communities, as well as sites of historical and cultural significance for Indigenous Peoples, like Herschel Island in Yukon (Radosavljevic et al. 2016). Although sea level rise is not a risk for many communities, ...
... The upfjord part of Spit 4 continued to retreat during the study period, whereas the downfjord part of Spit 4, which did not receive direct waves due to the growth of Spit 5 in 2017, stopped retreating since 2017. The newly developed spits reduce the morphodynamics of the existing spits by intercepting the incoming sediment or forming a shadow zone to reduce the effect of the wave (Carter and Orford, 1993;Radosavljevic et al., 2016). The breaching of spits is commonplace and considered the result of runoff by snow meltwater and, to a lesser degree, glacier meltwater. ...
... Gravel beaches with negligible net volume difference appear to serve as a conduit for alongshore sediment transport. Although the presence and growth of the spits signify the role of waves in sediment transport, coastal erosion is not prominent compared to the open Arctic coasts (Lantuit and Pollard, 2008;Jones et al., 2009;Lantuit et al., 2012;Barnhart et al., 2014;Radosavljevic et al., 2016;Farquharson et al., 2018). The cliff face is characterized by gully erosion and solifluction, suggesting that terrestrial hydrological processes linked to runoff and thawing of permafrost rather than by wave activities played a pivotal role in the cliff erosion (e. g., Christiansen et al., 2013;de Haas et al., 2015;Sessford et al., 2015a). ...
Recent global warming triggered pronounced geomorphic changes such as coastal retreat and delta progradation along the coastlines of the Arctic regions. Coastal morphodynamics and associated sediment transport at the Arctic fjord head remain relatively unexplored due to the logistically limited accessibility to the field area, especially at short-term temporal scales. A repeat survey using an unmanned aerial vehicle (UAV)-assisted photogrammetry was conducted to quantify the annual morphodynamics of gravel spit complexes developed on the tidal delta plain of the deglaciated Dicksonfjorden, Svalbard of Arctic. Results show that the spit morphodynamics varies in time and space with an overall downfjord increase in the growth and migration rate of the spits. The youngest spits elongated 22 m yr⁻¹ and migrated landward 4.3 m yr⁻¹ between 2015 and 2019, marking the most pronounced spit morphodynamics documented to date in the Svalbard fjord systems. The spit morphodynamics is driven primarily by longshore drift and to a lesser degree by overwash processes. Gravels constituting the spits originate from the unconsolidated debris-flow deposits of old alluvial fans, which locally retreat 0.5 m yr⁻¹. The growth of the spit complexes is also fed by snow meltwater discharge on the alluvial fans, accounting for a downfjord imbrication of angular gravel layers that are intercalated with interlaminated sands and muds on the landward sides of the spits. The breached spits at the most upfjord location have remained stationary during the study period and presumably since the 1930s. Rapid delta progradation combined with an isostatic rebound after the Little Ice Age (LIA) has decreased spit morphodynamics on the tidal delta plain upfjord in Dicksonfjorden with infrequent and insignificant wave influence. Sparse distribution of the isolated spits signifies the intermittent spit development, which is constrained by the proximity to the protruded alluvial fans. The spit complexes in Dicksonfjorden highlight that climate change accelerates coastal geomorphic changes at the fjord head by enhancing wave intensity and regulating episodic sediment delivery that led to the downfjord shift in the locus of wave shoaling.
... Qikiqtaruk/Herschel Island Territorial Park is an important heritage site in the Western Canadian Arctic. Qikiqtaruk and its heritage resources are currently being threatened by storm surges and erosion caused by sea ice depletion due to the ongoing impacts of climate change [37]. ...
... Herschel Island is approximately 101 square kilometers in size and is located in the Beaufort Sea off the north coast of the Yukon Territory (Fig. 4) [35] Pauline Cove is located on the northern corner of Qikiqtaruk/Herschel Island Territorial Park Pauline Cove (see Fig. 4) and is home to Inuvialuit and Euro-North American heritage resources that are currently threatened by storms, flooding, landslides and erosion caused by the disappearance of sea ice [5,22,28,37]. Nineteen historic structures remain standing at Pauline Cove and are related to the American Steam Whaling Era and later fur trade in the late 19th and early 20th centuries. Alongside these are buildings associated with Anglican missionaries, the Northwest Mounted Police, the Hudson Bay Company and other traders. ...
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The digital preservation of heritage resources has emerged as an essential method for communicating the significance of artifacts, buildings, and landscapes to descendant communities and the wider public. While virtual representations are becoming more commonplace, physical representations (physicalization) of heritage sites via 3D printing are used to a lesser degree. Physicalization provides new perspectives through the interplay between touch and vision and can facilitate a deeper understanding of the history being conveyed. This paper discusses how the physical models of heritage buildings and landscape features on Qikiqtaruk/Herschel Island Territorial Park were created from terrestrial laser scanning and UAV photogrammetry data. We demonstrate how to use this physicalization of polar heritage to communicate the significance of the buildings and landscape of the island to the local Indigenous communities and global audiences, as well as how they are being threatened by climate change. We also explore the transformation of a cove on the island into puzzles and data sculptures. In addition to the Cove, the fabricating of important buildings on larger scales has been a requirement. This multi-scale printing raises the issue of connecting the large-scale buildings with their small instances/copies on the Island (similar to focus + context visualization in the digital form). Due to the limitation of physicalization compared with digital representations, new methods, metaphors and designs are needed for supporting focus + context visualization. We have designed and implemented several such methods in our specific physicalization of heritage buildings and landscape on Qikiqtaruk/Herschel Island. We presented our physicalizations to the members of the Inuvialuit community of Aklavik NWT and received a positive response.
... Historical and research biases have led to the majority of shoreline change observations in the Arctic focusing on discrete sections of unlithified erosive coasts, primarily ice-rich permafrost bluffs. Examples include Drew Point, Elson Lagoon and Barter Island on the US Beaufort coast, Herschel Island on the Canadian Beaufort coast, Baydaratskaya Bay on the Kara coast and Muostakh Island on the Laptev coast 24,26,29,[123][124][125][126] . Less work has focused on, or included, stable or accretional landforms 13,27,42,43,55 , lithic coasts 127,128 or the interaction of landforms along more extensive stretches of coasts 27,55,91,129,130 . ...
... The acceleration in coastal erosion induces rapid changes in the coastal environment, creates risks for subsistence-based lifestyles 157 and threatens cultural heritage 126,158,159 , coastal communities 157,160 and infrastructure hubs 161,162 . Risks include the destruction of buildings and roads, loss of access to traditional hunting grounds and destruction of archaeological remains and cultural sites. ...
Abstract | Arctic coasts are vulnerable to the effects of climate change, including rising sea levels and the loss of permafrost, sea ice and glaciers. Assessing the influence of anthropogenic warming on Arctic coastal dynamics, however, is challenged by the limited availability of observational, oceanographic and environmental data. Yet, with the majority of permafrost coasts being erosive, coupled with projected intensification of erosion and flooding, understanding these changes is critical. In this Review, we describe the morphological diversity of Arctic coasts, discuss important drivers of coastal change, explain the specific sensitivity of Arctic coasts to climate change and provide an overview of pan-Arctic shoreline change and its multifaceted impacts. Arctic coastal changes impact the human environment by threatening coastal settlements, infrastructure, cultural sites and archaeological remains. Changing sediment fluxes also impact the natural environment through carbon, nutrient and pollutant release on a magnitude that remains difficult to predict. Increasing transdisciplinary and interdisciplinary collaboration efforts will build the foundation for identifying sustainable solutions and adaptation strategies to reduce future risks for those living on, working at and visiting the rapidly changing Arctic coast.
... It is classified as Dsc (subarctic climate) in the Köppen-Geiger climate classification [37]. Winds predominantly blow from ESE and NW directions [38]. Wind direction and wind speed have the potential to influence hydrodynamics such as currents [30] and upwelling [39]. ...
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The Arctic is greatly affected by climate change. Increasing air temperatures drive permafrost thaw and an increase in coastal erosion and river discharge. This results in a greater input of sediment and organic matter into nearshore waters, impacting ecosystems by reducing light transmission through the water column and altering biogeochemistry. This potentially results in impacts on the subsistence economy of local people as well as the climate due to the transformation of suspended organic matter into greenhouse gases. Even though the impacts of increased suspended sediment concentrations and turbidity in the Arctic nearshore zone are well-studied, the mechanisms underpinning this increase are largely unknown. Wave energy and tides drive the level of turbidity in the temperate and tropical parts of the world, and this is generally assumed to also be the case in the Arctic. However, the tidal range is considerably lower in the Arctic, and processes related to the occurrence of permafrost have the potential to greatly contribute to nearshore turbidity. In this study, we use high-resolution satellite imagery alongside in situ and ERA5 reanalysis data of ocean and climate variables in order to identify the drivers of nearshore turbidity, along with its seasonality in the nearshore waters of Herschel Island Qikiqtaruk, in the western Canadian Arctic. Nearshore turbidity correlates well to wind direction, wind speed, significant wave height, and wave period. Nearshore turbidity is superiorly correlated to wind speed at the Beaufort Shelf compared to in situ measurements at Herschel Island Qikiqtaruk, showing that nearshore turbidity, albeit being of limited spatial extent, is influenced by large-scale weather and ocean phenomenons. We show that, in contrast to the temperate and tropical ocean, freshly eroded material is the predominant driver of nearshore turbidity in the Arctic, rather than resuspension, which is caused by the vulnerability of permafrost coasts to thermo-erosion.
... Potential impacts of permafrost degradation and coastal erosion on civil infrastructure have been long discussed in the literature [12][13][14][15][16][17]. Coastal erosion along permafrost coastlines and the subsequent land loss and flooding also result in widespread damage to civil infrastructure [18][19][20][21][22][23]. Uneven surfaces created by differential thaw settlement can affect the functionality and serviceability of underground or aboveground power lines and pipeline systems for water, sewage, and fuel. ...
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This paper presents the results of a community survey that was designed to better understand the effects of permafrost degradation and coastal erosion on civil infrastructure. Observations were collected from residents in four Arctic coastal communities: Point Lay, Wainwright, Utqiaġvik, and Kaktovik. All four communities are underlain by continuous ice-rich permafrost with varying degrees of degradation and coastal erosion. The types, locations, and periods of observed permafrost thaw and coastal erosion were elicited. Survey participants also reported the types of civil infrastructure being affected by permafrost degradation and coastal erosion and any damage to residential buildings. Most survey participants reported that coastal erosion has been occurring for a longer period than permafrost thaw. Surface water ponding, ground surface collapse, and differential ground settlement are the three types of changes in ground surface manifested by permafrost degradation that are most frequently reported by the participants, while houses are reported as the most affected type of infrastructure in the Arctic coastal communities. Wall cracking and house tilting are the most commonly reported types of residential building damage. The effects of permafrost degradation and coastal erosion on civil infrastructure vary between communities. Locations of observed permafrost degradation and coastal erosion collected from all survey participants in each community were stacked using heatmap data visualization. The heatmaps constructed using the community survey data are reasonably consistent with modeled data synthesized from the scientific literature. This study shows a useful approach to coproduce knowledge with Arctic residents to identify locations of permafrost thaw and coastal erosion at higher spatial resolution as well as the types of infrastructure damage of most concern to Arctic residents.
... Arctic coastal erosion, often in combination with other climaterelated coastal hazards (that is, sea-level rise, permafrost thaw and storms), causes relevant socioeconomic damage 37,38 , including irreversible heritage data loss 39,40 . In Alaska, entire villages are already facing the need for relocation 41,42 . ...
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Arctic coastal erosion damages infrastructure, threatens coastal communities and releases organic carbon from permafrost. However, the magnitude, timing and sensitivity of coastal erosion increase to global warming remain unknown. Here we project the Arctic-mean erosion rate to increase and very likely exceed its historical range of variability before the end of the century in a wide range of emission scenarios. The sensitivity of erosion to warming roughly doubles, reaching 0.4–0.8 m yr−1 °C−1 and 2.3–4.2 TgC yr−1 °C−1 by the end of the century. We develop a simplified semi-empirical model to produce twenty-first-century pan-Arctic coastal erosion rate projections. Our results will inform policymakers on coastal conservation and socioeconomic planning, and organic carbon flux projections lay out the path for future work to investigate the impact of Arctic coastal erosion on the changing Arctic Ocean, its role as a global carbon sink, and the permafrost–carbon feedback. Coastal erosion in the Arctic is caused by permafrost thaw and wave abrasion enhanced by sea ice melt, both of which will increase under climate change. Projections of erosion rate across the Arctic indicate that mean erosion rates will rise beyond historical precedent over the twenty-first century.
This paper systematically reviews publications for the period 2002–2020 addressing the barriers to climate adaptation of cultural and natural heritage in the Northern and Southern poles. Climate change and its socio-economic implications deteriorate different forms of cultural and natural heritage, including archaeological sites, historic buildings, and indigenous heritage in the polar regions. Climate adaptation of cultural and natural heritage of polar regions is challenged due to the barriers, constraints, and limitations of various factors such as lack of awareness of polar heritage, remoteness of the sites, and lack of tools and facilities. This paper first presents the general characteristics of 76 documents out of 218. It then analyzes the barriers derived from the content analysis of the publications. Despite growing interest in polar studies, incomplete and inaccurate data and inventories and facilities and tools as technological constraints negatively affect building climate adaptation of polar heritage. Following that, existing regulations and organizations are found to be ineffective and slow to address the issues of communication and collaboration for building climate adaptation of polar heritage. The findings will discuss the policy implications of understanding barriers and tackling them to facilitate the climate adaptation of polar heritage.
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In this study, remote sensing analysis of coastal erosion is conducted for three typical regions of Alaska and Eastern Siberia based on remote sensing data collected between 1974 and 2017. The comparative studies were made on the difference in coastal erosion at different latitudes and the difference and influencing factors in coastal erosion at similar latitudes. The coastline retreatment is used to indicate coastal erosion. It is found that the most extensive erosion occurred along Alaska’s coast, followed by that of the Eastern Siberian coasts. Based on the analysis of the historical time series of snow and ice as well as climate data, it is found that at similar latitudes, the erosion of the Arctic coasts is closely related to the trend and fluctuations of the sea surface temperature (SST). Specifically, it is found that in Alaska, coastal erosion is closely related to the fluctuation of the SST, while in Eastern Siberia, it is related to the increasing or decreasing trend of the SST. A decreasing trend is associated with low coastal erosion, whereas an increasing trend is associated with accelerated coastal erosion. In the Arctic, the strong fluctuations of the SST, the continuous decline of the sea ice cover, and the consequent increase of the significant wave height are the critical factors that cause changes in coastal permafrost and coastal erosion.
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Mitigating, or adapting to, the impacts of environmental change on coastal landscapes, from both social and engineering perspectives, requires accurate baseline data that must be related to geomorphic processes. However, the inherent social and environmental dynamics of the coastal zone set up a contentious situation for decision makers and researchers because of the real, perceived, and stochastic nature of catastrophic threats to human life and property loss. Anecdotal accounts and first person observations generally propel the media and influence governmental policy far more effectively than scientific data. However, claims of extreme erosion rates are more adequately addressed through photogrammetric studies of erosion. Contrary to anecdotal accounts from Shishmaref, Alaska, sequential aerial photographs from 1950 to 2007 reveal that erosion has increased on the south-facing shores of the Chukchi Sea, while prior to 1977, erosion was higher on the north-facing shores such as Shishmaref. In addition, comparisons of property records indicate that high rates of erosion prevailed prior to 1950. Several engineering solutions were attempted in Shishmaref between 1983 and 2003, including gabions and cinder block/boulder/cobble revetments, leading to increased end-around erosion downdrift and an erosion rate twice that of undeveloped, unarmored shorelines. To adapt to heightened erosion rates, societies should either retreat from the shore or confront ever-increasing engineering costs.
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Permafrost landscapes experience different disturbances and store large amounts of organic matter, which may become a source of greenhouse gases upon permafrost degradation. We analysed the influence of terrain and geomorphic disturbances (e.g. soil creep, active-layer detachment, gullying, thaw slumping, accumulation of fluvial deposits) on soil organic carbon (SOC) and total nitrogen (TN) storage using 11 permafrost cores from Herschel Island, western Canadian Arctic. Our results indicate a strong correlation between SOC storage and the topographic wetness index. Undisturbed sites stored the majority of SOC and TN in the upper 70 cm of soil. Sites characterised by mass wasting showed significant SOC depletion and soil compaction, whereas sites characterised by the accumulation of peat and fluvial deposits store SOC and TN along the whole core. We upscaled SOC and TN to estimate total stocks using the ecological units determined from vegetation composition, slope angle and the geomorphic disturbance regime. The ecological units were delineated with a supervised classification based on RapidEye multispectral satellite imagery and slope angle. Mean SOC and TN storage for the uppermost 1 m of soil on Herschel Island are 34.8 kg C m^-2 and 3.4 kg N m^-2
The Thule migration from Alaska to the eastern North American Arctic is central to the understanding of Inuit history. However, despite decades of study, its timing remains controversial, with recent reappraisals suggesting that it may have occurred much later than the date of A.D. 1000 most often assumed for it. In this paper, we present newly obtained radiocarbon dates from two early Thule sites, Nelson River (OhRh-1) and Washout (NjVi-2), located on the Beaufort Sea and Amundsen Gulf coasts. This region is crucial to any understanding of the migration, because Thule Inuit would have had to pass through it in order to reach the eastern Arctic. Nelson River in particular has long been considered a good candidate for the earliest Thule site east of Alaska, based on a number of lines of evidence including the presence of both Natchuk and Sicco harpoon heads. In this paper, we present new dates for Nelson River and Washout that demonstrate that neither site was occupied before the thirteenth century A.D. The new dates have profound implications for Arctic archaeology, because they strengthen the case for a thirteenth-century migration, and by doing so demonstrate that it was more rapid and widespread than has generally been believed. The dates also suggest that the "Classic" Thule period is a relatively brief phenomenon, lasting perhaps only 200 years or less, before being rapidly reorganized into the diversity of Inuit societies encountered in later Arctic history.
Ice encroachment onto land occurs mainly during the period of complete ice cover and takes two basic forms, both of which are associated with sediment transport to differing degrees. In ice ride-up, unbroken sheets slide over frozen to shallowly thawed beaches or barriers for distances from 1 to over 100m. In ice pile-up, the advancing sheets crumble, building rubble piles up to 20m high that commonly contain a few percent of intermixed sediment entrained from as much as 50m seaward and 5m water depth. -from Authors
A simple model is developed to predict the overall horizontal retreat of a frozen cliff fronted by a beach due to a storm surge on the Beaufort Sea coast. In this thermal and mechanical erosion model, storm surge and wave action on the frozen cliff causes the convective heat transfer and melting of the ice-bonded cliff sediment, which supplies coarse sediment on the beach whereas fine sediment is assumed to be transported offshore. The volume balance for the unfrozen coarse sediment on the beach is used to predict the vertical beach erosion. When the frozen beach sediment is exposed to wave action, the beach erosion is controlled by the convective heat transfer and melting of the frozen beach sediment. The developed model is compared and calibrated using the observed cliff retreat due to a September, 1993 storm on the Canadian Beaufort Sea coast. The calibrated model is then used to assess the degree of importance of various factors that affect the thermal and mechanical erosion of the frozen cliff and beach. This assessment suggests that the accurate prediction of the cliff and beach erosion will require quantitative data on storm surge elevation and duration, cliff height, seawater temperature and salinity, sediment characteristics and wave conditions.
A new scale is proposed that categorizes impacts to natural barrier islands resulting from tropical and extra-tropical storms. The proposed scale is fundamentally different than existing storm-related scales in that the coupling between forcing processes and the geometry of the coast is explicitly included. Four regimes, representing different levels of impact, are defined. Within each regime, patterns and relative magnitudes of net erosion and accretion are argued to be unique. The borders between regimes represent thresholds defining where processes and magnitudes of impacts change dramatically. Impact level 1 is the 'swash' regime describing a storm where runup is confined to the foreshore. The foreshore typically erodes during the storm and recovers following the storm; hence, there is no net change. Impact level 2 is the 'collision' regime describing a storm where the wave runup exceeds the threshold of the base of the foredune ridge. Swash impacts the dune forcing net erosion. Impact level 3 is the 'overwash' regime describing a storm where wave runup overtops the berm or, if present, the foredune ridge. The associated net landward sand transport contributes to net migration of the barrier landward. Impact level 4 is the 'inundation' regime describing a storm where the storm surge is sufficient to completely and continuously submerge the barrier island. Sand undergoes net landward transport over the barrier island; limited evidence suggests the quantities and distance of transport are much greater than what occurs during the 'overwash' regime.