Long-Term Evolution and Monitoring at High Temporal Resolution of a Rapidly Retreating Cliff in a Cold Temperate Climate Affected by Cryogenic Processes, North Shore of the St. Lawrence Gulf, Quebec (Canada)

Abstract

This article focuses on the quantification of retreat rates, geomorphological processes, and hydroclimatic and environmental drivers responsible for the erosion of an unconsolidated fine-sediment cliff along the north shore of the Gulf of St. Lawrence (Quebec, Canada). Annual monitoring using field markers over a period of twenty years, coupled with photo interpretation and historical archive analysis, indicates an average annual erosion rate of 2.2 m per year between 1948 and 2017. An acceleration in retreat occurred during the last 70 years, leading to a maximum between 1997 and 2017 (3.4 m per year) and 2000–2020 (3.3 m per year). Daily observations based on six monitoring cameras installed along the cliff between 2008 and 2012 allowed the identification of mechanisms and geomorphological processes responsible for cliff retreat. Data analysis reveals seasonal activity peaks during winter and spring, which account for 75% of total erosional events. On an annual basis, cryogenic processes represent 68% of the erosion events observed and subaerial and hydrogeological processes account for 73%. Small-scale processes, such as gelifraction, solifluction, suffosion, debris collapse, and thermoabrasion, as well as mass movement events, such as slides and mudflows, induced rapid cliff retreat. Lithostratigraphy and cliff height exert an important control on erosion rates and retreat modes, which are described by three main drivers (hydrogeologic, cryogenic, and hydrodynamic processes). Critical conditions promoting high erosion rates include the absence of an ice-foot in winter, the absence of snow cover on the cliff face allowing unrestricted solar radiation, the repetition of winter warm spells, snow melting and sediment thawing, and high rainfall conditions (>30 mm or SPI > 2). The relationships between hydroclimatic forcing and retreat rates are difficult to establish without taking into account the quantification of the geomorphological processes involved. The absence of quantitative data on the relative contribution of geomorphological processes can constitute a major obstacle in modeling the retreat of cliffs with regard to climate change.

Sedimentary Coastal Cliff Erosion in Greenland

“…Coastal dynamics are highly heterogeneous around the polar ocean with the highest erosion rates along the Siberian and Alaskan coasts, and stable or aggrading coasts in Nunavut and in Greenland (B. M. Jones et al., 2020; Lantuit et al., 2012). Coasts are eroding as a response to the combined action of different forcings such as rising temperatures and intensifying hydrodynamic conditions (Bernatchez et al., 2021). The predominantly lithified coasts in Nunavut (Canada) and Greenland contain large volumes of glacially derived, coarse sediments with very little to no ground ice (St‐Hilaire‐Gravel et al., 2010).…”

Identification of Landslide types in cliffs between Ancon and Anconcito, Santa Elena, Ecuador

“…La erosión en acantilados representa un peligro en muchas áreas a través del desprendimiento de rocas a pequeñas escala y eventos de deslizamientos de tierra más grandes (Dickson & Perry, 2016). Durante mucho tiempo se ha identificado que la energía entregada al pie de los acantilados costeros a través de olas rompientes provoca el retroceso costero (Castedo et al, 2012;Xiang & Istrati, 2021;Zhang et al, 2021) y también puede desencadenar varios tipos de movimientos masivos, incluidos derrumbes, fallas de bloques y deslizamientos de tierra (Bernatchez et al, 2021). La socavación que se presenta en los acantilados por acción de las olas (Bernatchez & Dubois, 2004) y la posterior falla masiva es el mecanismo por el cual la mayoría de los acantilados costeros se erosionan (Costa et al, 2019), independientemente de su litología (Lim et al, 2011;Young & Ashford 2008).…”

Experimental field study on the fatigue and failure mechanisms of coastal chalk cliffs: Implementation of a multi-parameter monitoring system (Sainte-Marguerite-sur-Mer, France)

“…Cliff failure results from the interaction of both internal (e.g., rock strength, tectonics) and external factors. In coastal cliff environments, these external factors can include subaerialincluding subsurfaceagents (e.g., precipitation (Duperret et al, 2002;Brooks et al, 2012;Bernatchez et al, 2021;Young et al, 2021), water table fluctuations (Hutchinson, 1969;Lageat et al, 2006;Pierre and Lahousse, 2006), variations in temperature (Bernatchez et al, 2011(Bernatchez et al, , 2021Letortu et al, 2015a)), marine actions (e.g., mean sea-level variations, tide, sea state (Guilcher, 1954;Robinson, 1977;Sunamura, 1977;Carter and Guy, 1988)) and anthropogenic phenomena (e.g., coastal defence structures that modify sediment transport (Costa et al, 2004)). In other environments, such as glacial and mountain regions, monitoring projects have identified the influence of rainfall (e.g., Rapp, 1960;André, 1997;Ilinca, 2009;Zielonka and Wrońska-Wałach, 2019;Mainieri et al, 2020), snowmelt (Reid et al, 1988), freeze-thaw cycles (e.g.…”