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Département Géochimie, Environnement, Ecoulement, Réacteurs industriels et Cristallisation (GENERIC), Centre Sciences des Processus industriels et Naturels (SPIN), École des Mines de Saint-Etienne, 158 cours Fauriel, Saint-Etienne, Cedex 2, 42023, France
In order to assess a cliff&rss vulnerability to erosion, researchers must consider a number of parameters that collectively account for all possible erosional processes. The authors have developed a radial diagram that allows the most active processes of erosion to be visualized (e.g. hydrodynamic, gravity-driven or atmospheric), and when such diagrams are presented on a map, they can be used to rapidly identify the contributing erosional processes at a given location. The diagram, developed for the Baie des Chaleurs region (eastern coast of Canada), displays numerical values that represent the relative importance of various weakening parameters for a set of cliffs. In addition, a colour code represents the dominant lithology, and the diagram diameter is a function of the erosion rate. The data for each diagram are based on field observations, experimental work and results of mineralogical and petrophysical analyses. Ten fundamental parameters were used to assess the structural, petrophysical and environmental processes of erosion: porosity, percentage of matrix or cement, homogeneity of the stratification, presence of schistosity, fracture density, number of fracture sets, presence of faults, dip of the strata, effect of waves, and the presence of groundwater. Coastal managers can use these diagrams in conjunction with natural risk maps to estimate the vulnerability of a cliff and decide whether engineering structures are required for preservation.
