| Titre | Impacts of four storms in December 2010 on the eastern Shore of Nova Scotia |
| Télécharger | Téléchargements |
| Auteur | Taylor, R B; Frobel, D; Mercer, D; Fogarty, C; MacAuley, P |
| Source | Commission géologique du Canada, Dossier public 7356, 2013, 53 pages, https://doi.org/10.4095/292440 (Accès ouvert) |
| Image |  |
| Année | 2013 |
| Éditeur | Ressources naturelles Canada |
| Document | dossier public |
| Lang. | anglais |
| DOI | https://doi.org/10.4095/292440 |
| Media | en ligne; numérique |
| Formats | pdf |
| Province | Nouvelle-Écosse |
| SNRC | 11D/10; 11D/11 |
| Lat/Long OENS | -63.5000 -62.6667 44.8333 44.5000 |
| Sujets | études côtières; milieu côtièr; érosion côtière; gestion côtière; variations du littoral; littoraux; tempêtes; dépôts de tempête; changements du niveau de la mer; érosion; marées; dépôts cotiers; effets
sur l'environnement; sédimentologie; géologie de l'environnement; Nature et environnement |
| Illustrations | location maps; photographs; profiles; tables; aerial photographs; plots |
| Programme | Infrastructure côtière, Géosciences de changements climatiques |
| Diffusé | 2013 04 05 |
| Résumé | (disponible en anglais seulement)
A series of intense low pressure systems struck the Atlantic Maritime Provinces during each week in December 2010. Record storm surges during December 21 and 27
most impacted the shores of Cape Breton Island and southern Gulf of St. Lawrence. Impacts along the coastal highlands of Cape Breton Island were compounded by high river discharge and slope instability caused by heavy rainfall during the December 14
and 21 events.
Detailed observations and repetitive surveys of physical impacts to specific shore types from the December 2010 storms were limited to shores east of Halifax, Nova Scotia. The rapid succession of storms prohibited shoreline
recovery and resulted in net shoreline retreat. Cumulative impacts of the storms included: an upper beach and backshore dune retreat of 7 to 9 m along sand and mixedsediment barrier beaches; a beach crest retreat of 2 to 4 m across high and low
gravel barriers respectively; and a cliff top erosion of 1 to 1.8 m (between September 2010 and March 6, 2011) which was 4 to 7 times the average annual rate compiled between 1986 and 2009. Despite accelerated shore erosion caused by these storms,
longer term evolutionary trends observed at select shores were only slightly altered.
Longshore variations of storm impacts on specific beaches were a function of antecedent shore conditions. (a) At Miseners-Long Beach, representative of a high
gravel barrier, increased changes across the upper beach and backshore signal future increased beach mobility, instability and a shift toward a low gravel barrier beach. (b) At Cow Bay Beach, representative of a low gravel barrier, the loss of small
segments of high, narrow barrier, and the initiation of a new tidal channel signal continued rapid beach migration into Cow Bay Lake. (c) At Lawrencetown Beach, representative of a mixed sediment barrier, variable changes along the backshore revealed
different longer term responses. To the east sediment deposition into backshore craters is depleting shoreface sand reserves and accelerating the breakdown of adjoining foredunes. To the west the movement of large quantities of coarse clasts to the
upper beach imply it is evolving toward a high gravel barrier similar to Miseners-Long Beach. (d) At Conrads Beach, representative of a sand barrier, contrasting beach responses were recorded east and west of Fox Point. To the east, a maximum
foredune retreat of 9.1 m was caused by repeated wave attack. To the west the foredune was cut back, however the change only represented a temporary interruption in a recent phase of foredune progradation since a tidal inlet was closed in the late
1980s. |
| Résumé | (Résumé en langage clair et simple, non publié)
Une série de tempêtes intenses a frappé les provinces de l'Atlantique chaque semaine, en décembre 2010. Les 21 et 27 décembre, des ondes de
tempête records ont surtout touché les côtes de l'île du Cap-Breton et le sud du golfe du Saint-Laurent. Les incidences le long de la côte des hautes terres de l'île du Cap-Breton ont été aggravées par des débits fluviaux de pointe et une instabilité
de pente causée par des pluies abondantes. Les observations de terrain détaillées se sont limitées à la côte est de Halifax, en Nouvelle-Écosse. La rapide succession de tempêtes a empêché la récupération le long du rivage, et a entraîné un recul du
trait de côte. Les incidences cumulatives de toutes les tempêtes comprennent : le recul du sommet de la plage et des dunes de l'arrière-plage de 7 à 9 m pour les plages de sable, le recul d'une crête de plage de 2 à 4 m à travers un haut et un bas
cordon littoral de graviers, respectivement, et l'érosion du sommet d'une falaise de 1 à 1,8 m, soit de 4 à 7 fois plus élevé que le taux moyen annuel compilé entre 1986 et 2009. Nous pouvons utiliser les renseignements recueillis afin d'améliorer et
de gérer nos littoraux, pour la sécurité des Canadiens. |
| GEOSCAN ID | 292440 |
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