Relation between planimetric and volumetric measurements of permafrost coast erosion: a case study from Herschel Island, western Canadian Arctic

Figures & data

Fig. 1  Hypsometric tint and bathymetry map of Herschel Island in the Canadian Arctic with place names. Coastal areas are marked with the year of the LiDAR DEM acquisition used for calculations. Displayed are also four coastal units (east, north and west coast and Workboat Passage).

Fig. 2  Map of planimetric erosion inside belt transects on Herschel Island. Net rates of coastline movement in 2000–2011 were calculated from digitized coastlines.

Table 1 Coastline movement, volume decrease, sediment release and carbon and nitrogen fluxes in different coastal units. Volume decrease and sediment release rates include interpolated data for gap filling.

Coastal unit	Mean coastline retreat rate (m a^−1)	Mean coastline progradation rate (m a^−1)	Mean net coastline movement rate (m a^−1)	Mean volume decrease rate (m^3 m^−1 a^−1)	Total volume decrease rate (m^3 a^−1)	Mean sediment release rate (m^3 m^−1 a^−1)	Total sediment release rate (m^3 a^−1)	Organic carbon flux (kg C m^−1 a^−1)	Nitrogen flux (kg N m^−1 a^−1)	Total organic carbon flux (Tg C a^−1)	Total nitrogen flux (Tg N a^−1)	Percentage of excess ice (%)
East coast	0.85±0.95	0.19±3.74	−0.66±3.93	6.9±10.8	89 000	6.2±9.7	80 000	130.1	23.0	1.7	0.30	13.0
North coast	1.22±0.75	0.02±0.10	−1.20±0.79	73.1±30.3	1 111 000	71.6±29.7	1 088 000	1495.7	264.8	22.7	4.02	2.6
West coast	0.30±0.42	0.16±0.33	−0.13±0.62	23.6±24.5	189 000	23.0±23.9	185 000	480.4	85.0	3.9	0.68	4.5
Workboat Passage	0.16±0.35	0.72±0.77	0.56±0.84	1.1±3.1	13 000	0.9±2.6	11 000	19.3	3.4	0.2	0.04	35.0
Herschel Island	0.88±0.86	0.20±2.26	−0.68±2.48	29.0±37.2	1 404 000	28.2±36.2	1 364 000	589.8	104.4	28.5	5.05	/

Fig. 3  Map of volumetric erosion inside belt transects on Herschel Island. Net sediment release rates in 2000–2011 are based on DEM elevation changes.

Fig. 4  Scatterplot with linear best fit showing sediment release rates based on DEM elevation change compared to sediment release calculated from coastline retreat and cliff height.

Fig. 5  Coasts of Herschel Island can undergo a series of mass wasting and accumulation processes. Material is transported as mudflows, landslides and block failures before reaching the shore. (a) Slumping, mudflows and shore accumulations on Bell Bluff; (b) active-layer detachment on the east coast (marked with a white dashed line); (c) block failure on the north coast; and (d) retrogressive thaw slump on the east coast.

Fig. 6  Rate of change in coastline movement between 1970–2000 and 2000–2011. Coastline movement rates for 1970–2000 were estimated by Lantuit & Pollard (2008).

Lantuit H., Pollard W.H. Fifty years of coastal erosion and retrogressive thaw slump activity on Herschel Island, southern Beaufort Sea, Yukon Territory, Canada. Geomorphology. 2008; 95: 84–102.

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