| Coastal chalk cliffs in Upper Normandy (France) evolve through continuous erosion. From 2002 to 2009, ESTRAN organization (Scientific and Technical Space of Aquatic Resources and Navigation) conducted a weekly inventory of 331 cliff falls (location, volume, and dating) between Veules-les-Roses and Le Tréport (37.5 km). Many approaches have been performed on this database. Spatial approach has highlighted the Ailly Cape sector as the most sensitive to erosive dynamic. Temporal approach has underlined that winter has been the season most prone to erosion (in fallen volume as in number of falls), followed by autumn, spring. Summer has not been a season prone to cliff falls but falls could occur. Statistical approach has highlighted a main contrast between marine and sub-aerial weathering factors with a seasonal distribution. Marine factors have seemed predominant during winter (sub-aerial weathering agents remained but in lower proportion) whereas during summer, sub-aerial weathering factors have been predominant, ending in coastal cliff falls that have often been less numerous and less massive than in winter. Spatial analysis with the help of geomatic tools (spatial statistics, cartography...) has confirmed the cliff falls polarization and the distinctive behaviour of the Ailly Cape sector. |
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