Contrasting shoreline changes in the communities of Nunavik (northern Quebec, Canada), 1955 to 2020

Abstract:

Contrasting coastal environments are present along Canada’s northern coastline, making adaptation strategies highly site-specific. To better understand the response of Arctic and Subarctic coasts to increasing environmental pressure, shoreline changes in the 14 communities of Nunavik (northern Quebec, Canada) were investigated. Shoreline positions were acquired from aerial and satellite images between 1955 and 2020. Shoreline change rates were calculated for multiple time periods. With a wide range of geological, climatic, hydrodynamic and permafrost conditions, the coasts of Nunavik – from eastern Hudson Bay to Ungava Bay – present a wide range of morphology, stability, drivers of change and hazards, in a context of a relative sea-level fall due to glacial isostatic adjustment. The idea behind a general trend of coastal progradation favored by the still active and rapid postglacial emergence context is misleading. Indeed, we observed significant spatio-temporal differences between these communities. Some of them, located on unlithified materials (e.g. Umiujaq, Inukjuak, Akulivik, Salluit and Tasiujaq), show high rates of coastal erosion, sometimes influenced by extreme events (e.g. storm surges, permafrost thaw). The highest rates are found in Umiujaq, where a micro cliff has been eroding at a rate of about 1.5 m/yr since 2010. The other communities, located on rocky shores or in sheltered unlithified areas, have experienced relative progradation or stability. In most cases of landward shoreline retreat, long- and cross-shore sediment variability is induced by the construction of human infrastructure, further exacerbated by high anthropogenic activity (e.g. ATV) on the beaches and dunes. Finally, mapping and statistical analysis of coastal changes in Nunavik will be included in the ACD database and will provide an overview of the dynamics of emerging shores.